J Neurosurg $1:49-59, 1994 Extreme lateral transcondylar approach: technical improvements and lessons learned Ramesu P. Basu, M.D., LALIGAM N. SEKHAR, M.D., AND DONALD C. Wricut, M.D. Departments of Neurosurgery, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania, and George Washington University Medical Center, Washington, D.C. ~ Anextreme lateral transcondylar or extreme lateral transfacetal surgical approach was used to treat 22 patients with complex lesions over a 22-month period. The lesions included basilar invagination with vertebral artery pathology, giant aneurysm or arteriovenous fistula of the vertebral artery, meningioma, chordoma, chondro- sarcoma, and paraganglioma. The approach was used alone or in combination with a presigmoid petrosal or subtemporal-infratemporal approach. Refinements of the operative technique, treatment strategies for complex lesions, and the avoidance of complications are discussed. Complications included cerebrospinal fluid leakage, meningitis, pseudomeningocele, hemiparesis or quadri- paresis, lower cranial nerve deficits, and vertebral artery injury requiring repair. With treatment, major neu- rological deficits resolved completely in three patients and partially in two. There was no operative mortality, but four patients died during the follow-up period. For the 18 surviving patients, the mean preoperative and postoperative Karnofsky scores were 81 and 93, respectively. For the four who died, the mean preoperative Kamofsky score was 73 and the mean postoperative score was 63. Key Worps + transcondylar approach foramen magnum - jugular tubercle foramen magnum, lower clivus, and anterior aspect of the upper cervical areas is a chal- lenging neurosurgical problem that in the past has been associated with high morbidity and mortality rates and incomplete removal. Development of the extreme lat- eral transcondylar approach has allowed many of these lesions to be treated safely. Since our earlier experience with this technique, 25 further technical refinements have been made. These refinements have permitted us to treat several complex lesions, including vascular lesions of the vertebral ar- tery, basilar invagination, rheumatoid disease of the craniovertebral junction, and several intradural and ex- tradural tumors. A combination of this technique with a presigmoid petrosal or subtemporal-infratemporal approach has made accessible an increased range and size of lesions. Complications encountered in earlier studies cautioned us about particular problems. The technical advances that have resulted and other lessons learned from our experience are discussed. Meco of lesions situated in the anterior Clinical Material and Methods Between March, 1991, and December, 1992, 22 pa- tients were operated on via the extreme lateral transcon- J. Neurosurg. / Volume 81 / July, 1994 * aneurysm + chordoma + meningioma + operative technique dylar approach at the University of Pittsburgh Medical Center under the direction of two of the authors (L.N.S. and D.C.W.). Patient age ranged from 16 to 70 years, with a mean age of 35 years; there were 11 men and 11 women. Presenting symptoms varied from nonspe- cific headache to difficulty with swallowing, progres- sive quadriparesis, sensory disturbances, and attacks of vertebrobasilar insufficiency (Table 1). Patient exami- nations included magnetic resonance (MR) imaging and computerized tomography (CT), with the use of bone windows. These images indicated the extent and location of the lesion and allowed the surgeon to select the best operative approach. Cerebral arteriograms were obtained in 17 patients. In patients with neoplasms, the size and dominance of the vertebral artery, the anatomy of its branches, and the encasement of the vessels were studied. The domi- nance and communication of the sigmoid-transverse sinus were also examined in anticipation of possible venous injury. In one patient with basilar invagination and ischemic symptoms on neck extension (Case 12), angiography revealed transient occlusion of the abnor- mally placed vertebral artery upon neck extension. A balloon occlusion test of the internal carotid artery (ICA) was performed in three patients with extensive tumors involving the petrous or upper cervical ICA. In 49 R. P. Babu, L. N. Sekhar, and D. C. Wright TABLE | Chaical summary of patients® Case Sex, Location of Lesion & Preop Exam/ Surgical Patholo: No. Age (yrs) Prior Treatment Symptoms Approach By i F, 36 anterior C1~2 quadriparesis ELTF neurofibroma 2 F, 36 basilar invagination headaches ELTC rheumatoid arthritis 3 F,65 lower clivus to top of dens Oth, 10th CN paresis ELTC meningioma 4 Fl6 mid & lower clivus; prior tt 6th-7th CN paresi: ELTC, STIT chordoma surgery X 3 and irradiation 9th-11th CN paresis 5 F4l lower clivus, foramen magnum bilat 12th CN paresis, ELTC meningioma pyramidal & cerebellar signs 6 M, 49 lower clivus, petroclival region, —_[t 9th—-10th CN paresis, It ELTC meningioma jugular foramen; prior surgery cerebellar signs 7 M, 47 lower clivus, foramen magnum headaches ELTC meningioma 8 M, 41 mid clivus to C-2; prior lt 9th-1Lth CN paresis ELTC chordoma surgery and irradiation 9 E70 anterior C13 sensory Joss, headache ELTF meningioma 10 F, 48 mid & lower clivus, petrous It 7th-8th CN paisy, bilat ELTC, PS meningioma apex, Cavernous sinus; prior 9th-10th CN paresis, It surgery cerebellar signs BT M, 64 lower clivus, foramen magnum It 8th CN paresis, It cerebellar = ELTC meningioma sig 12 M, 32 C-4 (hemilamina), basilar transient ischemic attacks, vertebrectomy, C3-5 congenital bone invagination headache fusion, ELTC, ELTF —_ anomalies 13 F, 37 mid clivus to foramen magnum; — It 12th CN palsy, 9th-10th STIT, ELTC chordoma prior surgery & irradiation CN paresis 14 M, 70 VA gait ataxia ELTC, presigmoid giant VA aneurysm 15 M, 56 anterior Ct-2 rt hemiparesis ELTF meningioma 16 M, 48 lower clivus to C-2; prior bilat 9th-10th CN paresis, mild = ELTC meningioma surgery X 2 quadriparesis 17 F499 mid clivus to C-1 bilat pyramidal signs, headache ELTC meningioma 18 M, 66 mid clivus to C-1 bilat 9th-10th CN paresis STIT, ELTC chordoma 19 F 46 jugular foramen It 12th CN palsy ELTC glomus jugulare tumor 20° M,54 — anterior foramen magnum It upper extremity paresis, ELTC meningioma ataxia 21 M, 37 jugular foramen/lower clivus; It 6th-12th CN palsy, gait ELTC, PS glomus jugulare tumor prior surgery X 5 & irradiation — ataxia 22 F45 VA rt CS—6 hemiparesis, ELTF arteriovenous fistula of VA & weakness paravertebral vein at C-3 * Abbreviations: CN = cranial nerve(s), ELTF = extreme lateral transfacetal, ELTC = extreme lateral transcondylar, STIT = subtemporal-in- fratemporal, PS = petrosectomy, VA = vertebral artery. TABLE 1 (continued —) five patients embolization of the ascending pharyngeal artery supplying the tumor was performed. Seven of the 22 patients had undergone prior surgery via retrosigmoid, subtemporal, or transoral approaches. In this series treatment of complex lesions involved the combination of the extreme lateral transcondylar ap- proach with other approaches, such as the subtemporal- infratemporal approach in three cases and a presigmoid approach with varying degrees of petrosectomy in three other cases. One of the patients in this series (Case 14) has been reported previously. 50 Operative Technique Since this technique has been described else- where,'2'3 only refinements of the procedure are described here. Neurophysiological monitoring of so- matosensory evoked potentials, both hypoglossal nerves, and the ipsilateral vagus nerve is usually em- ployed. The patient lies in a modified Sugita lateral position. A C- or -shaped incision is used, depending upon the need to combine the transcondylar approach with a presigmoid petrosal approach, a subtemporal- infratemporal approach, or an occipitocervical fusion. J. Neurosurg. / Volume 81 / July, 1994 Lateral transcondylar approach TABLE 1 (continued)* Kamofsk: Exe nt of woe Follow-Up Follow-Up MRI . Score: * Follow-Up mor Complications Examinati Fusion Period Resection amination Results Preop/Last (mos) Follow-U P total none intact no tumor no 70/100 18 complete quadriparesis, CSF leak, VA intact (deficits resolved) — good yes 90/100 10 decompression occlusion, pseudoaneurysm, decompression delayed 7th & 11th CN paresis total Oth-12th CN paresis 9th-12th CN no tumor no 90/90 16 paresis improved subtotal none unchanged recurrence no 80/80} 10 (died) total worsened 12th CN paresis 12th CN paresis improved no tumor no 80/100 19 subtotal It hemiparesis, 12th CN paresis, hemiparesis resolved, died residual tumor no 70/60} 3 (died) 9th-10th CN palsy of pneumonia total none intact no tumor no 90/100 7 subtotal tt hemiplegia hemiparesis improving massive yes 70/604 10 (died) recurrence total delayed 11th CN paresis intact no tumor no 80/100 8 subtotal tt hemiparesis, It 12th CN palsy, tt 12th CN paresis; no regrowth of no 70/70 16 delayed hemiparesis due to hemiparesis & 7th CN clivus tumor, radiation palsy improved residue treated with gamma knife total meningitis intact no tumor no 90/100 9 excision of lesion, none intact not available yes 90/100 13 VA decompression total CSF leak, delayed neck titt & persistent CN palsies no tumor yes 80/90 15 pain occlusion of Oth-10th CN paresis intact patent graft no 80/100 15 aneurysm, vein graft total VA laceration (repaired) intact no tumor no 80/100 6 subtotal CSF leak, meningitis, hydrocephalus, quadriparesis improving _no tumor no 70/50+ 8 (died) occluded VA, quadriparesis, 9th-10th CN paresis total 12th CN paresis 12th CN paresis improved no tumor no 90/100 5 total worsened ipsilateral 9th—-10th CN. 10th-11th CN paresis no tumor yes 70/70 7 paresis improved total 9th-11th CN paresis persistent 9th-10th CN no tumor yes 80/80 9 paresis total none intact no tumor no 80/100 5 total hydrocephalus, CSF leak, CN paresis improving no tumor no 70/80 13 VA injury (repaired) occlusion of none hemiparesis resolved, not available no 80/90 15 fistula C5-6 improving * Abbreviations: MRI = magnetic resonance imaging; CN = cranial nerve(s); VA = vertebral artery; CSF = cerebrospinal fluid. + Best Karnofsky score prior to death. Early Dissection Dissection and elevation of the muscles is performed in layers, from a lateral to a medial direction (Fig. 1 upper left). Small cuffs of the sternomastoid, splenius capitis, and semispinal muscles are left attached to the bone for later reattachment. This technique differs from that of other authors, who elevate the muscles from a medial to a lateral direction. We prefer the lateral-to- medial elevation because it removes the muscle mass from the area where the lesion lies, thus providing max- imum exposure. The layer-by-layer dissection helps to identify the vertebral artery and the C-2 nerve root. J. Neurosurg. / Volume 81 / July, 1994 Vertebral Artery The vertebral artery is defined by using one of three landmarks: the transverse process of C-1, the C-2 nerve root which lies lateral to the artery, or the venous plexus around the artery (Fig. 1 upper right). The transverse foramen of C-1 is opened and the artery is mobilized medially from the C-2 root to the dural entrance point (Fig. 1 lower left). Division of the C-2 root (which can be resutured later) is essential for further mobilization inferior to the C-2 foramen. Anatomical variations must be recognized; sometimes the artery enters the dura be- tween C-2 and C-1. Occasionally, the ligament that sur- 51 Ci Transverse Process Atlanto-Occipital Joint R. P. Babu, L. N. Sekhar, and D. C. Wright Initial Dural Incision Fic. 1. Photographs of anatomical dissections illustrating the finer points of the transcondylar approach, from the left side. The cadaver was placed in the right lateral decubitus position, and an (-shaped skin and subcutaneous tissue flap was used. Upper Left: The sternomastoid, semispinal, splenius capitis, and the levator scapulae muscles have been elevated from the occipital bone and mastoid process. The occipital artery, the transverse process of C-1, and the attached oblique and recti muscles are visible. Upper Right: The muscles have been detached from the C-1 vertebra laterally and reflected medially. The C-1 and C-2 nerve roots (C,, C,) and the extradural vertebral artery from C-2 upward are visible. The vertebral venous plexus has been removed. Lower Left: The vertebral artery has been unroofed from C-2 through the dural entrance point. Alow mastoidectomy and a retrosigmoid craniectomy have been performed. The lateral third of the C-1 lamina has been removed. Lower Right: The extradural vertebral artery is reflected medially and the posterior third of the occipital condyle and lateral mass have been resected. The black thread marks the initial dural incision; the remaining incision encircles the vertebral artery (see also Fig. 2 upper right). rounds the artery and lies on the arch of C-1 is ossified, forming a bone tunnel. The artery may also turn sharply forward and laterally around the arch of C-1; in one of our patients it was lacerated at this point during dis- section and was successfully repaired. Mastoidectomy and Craniectomy Amastoidectomy is performed, extending anteriorly to the facial nerve canal and unroofing the lower half of the sigmoid sinus and the jugular bulb posteriorly. We find the mastoidectomy to be essential for all in- tracranial procedures. The retrosigmoid craniectomy includes the rim of the foramen magnum, and must be small so that occipitocervical fusion can be performed if necessary. 52 Condyle Resection For intradural lesions, one-third to one-half of the lateral mass of C-1 and the occipital condyle are re- moved, exposing at least 1 cm of dura anterior to the entrance of the vertebral artery (Fig. 1 lower right). More bone removal may be necessary as the tumor re- section progresses. For extradural tumors involving the occipital condyle, the entire condyle should be re- sected, and subsequent occipitocervical fusion is ad- visable. For vertebral artery or vertebrobasilar junction aneurysms, it is important to remove as much of the jugular tubercle as possible. Bone removal is of vital importance, improving the lateral exposure at the level of the foramen magnum. J, Neurosurg. / Volume 81 / July, 1994 Lateral transcondylar approach gular Bult Anterior Sir Vertebro-Basilar Junction Fic. 2. Photographs of anatomical dissections with the same specifications as Fig. 1. Upper Left: The dura has been opened with a small cuff left around the vertebral artery. The intra- and extradural portions of the hypoglossal nerve, the posterior inferior cerebellar artery, the partially resected oc- cipital condyle, and the anterior spinal artery are shown. CN XII = 12th cranial nerve. Lower: Photograph showing the vertebrobasilar junction. Upper Right: Photograph demon- strating dural closure. Also visible are the partially resected occipital condyle, the extradural portion of the hypoglossal nerve, and the jugular bulb. Dural Opening and Closure Whenever possible, the dura is opened with a small cuff remaining around it to allow watertight closure (Fig. 2 upper left). If the dura is excised because of tumor invasion, then the use of fascia lata, autologous fat, and fibrin glue, muscle closure in layers, and pro- phylactic cerebrospinal fluid (CSF) drainage help to prevent CSF leakage. Intradural Tumors Intradural tumors (usually meningiomas) may en- case the 10th, 11th, and 12th cranial nerves as well as the vertebral artery. Figure 2 upper right and lower il- lustrates an anatomical dissection of this region. Cra- nial nerve monitoring and dissection from a normal to an abnormal area are useful for cranial nerve preser- vation. The vertebral artery and its branches are usually protected by a thin arachnoid plane, which allows them to be dissected free; however, difficulty was encoun- tered in patients who had previously undergone surgery because of scar tissue. Great caution must be exercised J. Neurosurg. / Volume 81 / July, 1994 with the anterior spinal arteries, which may be encased. When the arachnoid plane between the tumor and the brain stem is poor, a thin layer of tumor must be left behind in order to avoid injury to the brain tissue, an- terior spinal veins, and perforating arteries. When the tumor extends above the level of the ninth cranial nerve (to the mid or upper clivus), the transcondylar approach is combined with a presigmoid petrosal approach, with or without division of the sigmoid sinus. By appropriately positioning the operating micro- scope, the surgeon can look ipsilaterally up to the level of the ninth cranial nerve and contralaterally to the level of the seventh cranial nerve. The division of the first two cervical rootlets and the first two dentate liga- ments allows the surgeon to look inferiorly to the level of the C-2 root. More inferiorly placed lesions require further inferior exposure of the vertebral artery. Aneurysms For giant vertebral artery and vertebrobasilar junc- tion aneurysms, proximal and distal control is obtained prior to dissection. Here again, the combination of a low presigmoid approach with division of the sigmoid sinus (after test occlusion with intrasinus pressure measurement and observation for brain swelling) may be necessary to obtain optimum exposure. Extradural Tumors For extradural lesions such as chordomas, the transcondylar approach combined with a subtemporal- infratemporal or bilateral transcondylar approach, per- formed in a staged fashion, may be necessary to achieve complete tumor resection. When the occipital condyle is resected completely, occipitocervical fusion is nec- essary, as in our Case 13 (see below). Lesions Below the Foramen Magnum For lesions located below the level of the foramen magnum, a transfacetal approach, with or without total exposure of the vertebral artery, is used. Depending upon whether the lesion is intradural or extradural, a small laminectomy or an anterolateral approach to the vertebral body may also be necessary. Illustrative Cases The following case reports illustrate some of the ap- plications of this approach to complex lesions as well as some of the problems encountered. Case 22: High Cervical Arteriovenous Fistula This 45-year-old Caucasian woman presented with a 2-year history of intermittent neck pain, tinnitus in the right ear, and progressive right upper-extremity weakness. Neurological examination revealed muscle wasting and weakness in the distribution of the C-5 and C-6 nerve roots, and generalized weakness and spas- ticity below this level. Magnetic resonance imaging showed a large venous sac compressing the spinal cord extradurally. A vertebral arteriogram revealed a large fistula between the artery and the venous plexus, with 53 Fic. 3. Case 22. Left: Magnetic resonance T,-weighted image, axial view, of the high cervical area showing a right vertebral arteriovenous fistula and dilated paravertebral veins. Right: Arteriogram showing the site of the fistula (arrow). a dilated venous varix at the C4—S level (Fig. 3). En- dovascular occlusion of the arteriovenous fistula was attempted but was unsuccessful; hence, surgical inter- vention was elected. Via the extreme lateral transfacetal approach, the transverse foramina of C-1, C-2, and C-3 were drilled away and the cervical portion of the vertebral artery was exposed. The fistula ruptured during exposure but bleeding was controlled by trapping the vertebral artery proximal and distal to the fistula. The fistula was in- terrupted and closed with 8-0 nylon suture. Postop- erative arteriography revealed a patent vertebral artery. Since the operation, the patient has steadily regained strength in her upper and lower limbs. At the last follow-up examination, she was living independently. Case 12: Congenital Lesion of the Craniovertebral Area This 32-year-old man presented with episodes of transient visual obscuration and loss of consciousness R. P. Babu, L. N. Sekhar, and D. C. Wright on looking upward, followed by severe headache. Neu- rological examination was entirely normal. Plain x-ray films of the neck and a CT scan with bone algorithms revealed a segmentation abnormality of C-4 with se- vere cord compression (Fig. 4 left and center). The atlas was occipitalized with the lateral mass of C-1 well in- side the foramen magnum. Arteriography showed com- plete occlusion of the right vertebral artery during ex- tension of the neck (Fig. 4 right). Abnormalities of the craniovertebral junction are usually treated via a transoral or transmaxillary ap- proach, but if they are associated with abnormalities of the vertebral artery, the extreme lateral transcondylar approach offers a valuable alternative. This approach was used in this patient, and the vertebral artery was completely decompressed from C-4 to the dural en- trance point. The abnormal C-4 body was resected to- tally, decompressing the spinal cord, and anterior in- terbody fusion was performed with banked fibular bone. The patient was maintained in a halo vest for 5 months. Fusion of the graft was complete and the patient was neurologically normal, asymptomatic, and working 8 months after surgery. Case 13: Extensive Skull-Base Chordoma This 37-year-old woman presented at another insti- tution complaining of difficulty with swallowing and a stiff neck of 3 months’ duration. She was diagnosed as having a clivus/foramen magnum chordoma (Fig. 5) and underwent a suboccipital craniectomy and partial removal of tumor at another institution, followed by 66 Gy of proton beam radiotherapy. She was later re- ferred to our center because of tumor regrowth. Neurological examination revealed paresis of the ninth and 10th cranial nerves and palsy of the 12th cra- nial nerve on the left side. Gross total tumor resection was performed in two operations. The first operation “ Fic. 4. Case 12. Left: Vertebral arteriogram, lateral view, with the patient’s neck in a neutral position, showing the hemicentrum of the C-4 vertebral body and the abnormal alignment of the neck. Center: Nonenhanced computerized tomography scan using a bone window showing the occipitalization of the atlas. Right: Vertebral angiogram revealing arterial occlusion with neck extension. 54 J. Neurosurg. / Volume 81 / July, 1994 Lateral transcondylar approach Fic 5. Case 13. Magnetic resonance images, nonenhanced sagittal view (A and B), nonenhanced axial view (C), and contrast-enhanced axial view (D), showing a large lower clivus/foramen magnum chordoma. was performed via a left subtemporal-infratemporal ap- proach. The second, to complete the tumor resection, was performed via an extreme lateral transcondylar ap- proach 3 days later (Fig. 6). A fusion operation was not performed initially because of the prior suboccipital craniectomy. However, a slowly progressive neck tilt and episodic neck pain developed, and occipitocervical fusion was subsequently performed using the right- sided occipital bone. The neck tilt improved and the pain symptoms resolved. The patient has a persistent 12th cranial nerve palsy, ipsilateral paresis of the ninth and 10th cranial nerves, and mild dysphagia. Her post- operative Karnofsky score’ is 90; she is very active and athletic, and has returned to work. When removing large extradural tumors, particularly a chordoma in the lower clivus/foramen magnum area, the extreme lateral transcondylar approach is often combined with a subtemporal-infratemporal approach, preserving hearing and facial nerve function. Alterna- tively, the transcondylar approach may be performed bilaterally and in stages. Such cases require a secure occipitocervical fusion, with adequate time after the fu- sion procedure before the second occipital condyle is Tesected. Fic. 6. Case 13. Postoperative magnetic resonance images, axial (left) and sagittal (right) views, showing complete re- section of the tumor. J. Neurosurg. / Volume 81 / July, 1994 Results The follow-up period ranged from 3 to 19 months, with a median period of 10 months (Table 1). In pa- tients with neoplasms, gross total resection was defined as the absence of tumor on postoperative MR imaging and the surgeon’s impression of gross total tumor re- moval. Based on these criteria, gross total resection was achieved in 13 of the 18 surviving patients. In the two patients with vascular lesions, complete extirpation was achieved, with a vein graft being used in the patient with an aneurysm. In patients with developmental or theumatoid lesions, complete decompression of the spinal cord and/or the medulla was achieved. Although there was no operative mortality, four pa- tients (Cases 4, 6, 8, and 16) died during the follow-up period. The first of these (Case 4) presented with a re- current, previously operated and irradiated chordoma and was treated by a partial tumor resection. She re- covered well but developed massive tumor recurrence and died 10 months later. The second (Case 6) had a recurrent meningioma that was treated with subtotal resection. He made a quick recovery from a mild post- operative hemiparesis and 12th cranial nerve paresis, but died unexpectedly from a virulent pneumonia after 3 months. The third patient (Case 8), also with a re- current, previously operated and irradiated chordoma, was treated with a subtotal tumor resection and was improving in spite of postoperative hemiparesis. He too developed massive tumor regrowth and died 10 months postoperatively. The fourth patient (Case 16) had a recurrent meningioma and suffered vertebral ar- tery occlusion and meningitis postoperatively. He was making a progressive recovery from quadriparesis and lower cranial nerve paresis when he died of an aspi- ration pneumonia 8 months after surgery. Deficits of the ninth and 10th cranial nerves undoubtedly contrib- uted to this condition. For the 18 surviving patients, the mean Karnofsky score® was 81 preoperatively and 93 postoperatively. For the four patients who died during the follow-up period, the mean preoperative Karnofsky score was 73 and the mean of their best scores postoperatively was 63. These four patients had all been operated on pre- 55 R. P. Babu, L. N. Sekhar, and D. C. Wright TABLE 2 TABLE 4 Outcome of patients with preoperative cranial nerve Outcome of patients with preoperative neurological (CN) deficits (excluding cranial nerve) deficits Outcome Outcome Preop No. of Preop No. of Deficit Cases Complete —_Partiat No Deficit Cases Complete _ Partial No Recovery Recovery Recovery Recovery Recovery Recovery 6th CN 2 1 0 1 hemiparesis 4 4 0 0 7th CN 1 0 1 0 hemiplegia 1 0 1 0 8th CN 3 1 0 2 quadriparesis 2 2 0 0 9th & 10th CN 9 6 1 2 sensory deficit 1 1 0 0 12th CN 4 1 2 1 cerebellar deficit 5 5 0 0 totals 19 9 4 6 totals 13 12 1 0 TABLE 3 TABLE 5 Outcome of patients with postoperative cranial nerve Outcome of patients with postoperative neurological (CN) deficits (excluding cranial nerve) deficits Outcome Outcome Postop No. of Postop No, of Deficit Cases Complete Partial No Deficit Cases Complete Partial No Recovery Recovery Recovery Recovery Recovery Recovery 7th CN 1 1 0 0 hemiparesis 2 2 0 0 9th & 10th CN 3 2 1 0 hemiplegia 1 0 1 0 1ith CN 4 2 2 0 quadriparesis 2 1 1 0 12th CN 5 2 2 1 cerebellar deficit 0 0 0 0 totals 13 7 5 1 totals 5 3 2 0 viously and three of the four had deteriorated postop- eratively. Cranial nerve function in patients in this series is shown in Tables 1, 2, and 3. Of the 19 instances of preoperative cranial nerve dysfunction, complete or partial recovery occurred in 13. Thirteen instances of new or worsened cranial nerve dysfunction were ob- served postoperatively, and complete or partial recov- ery was observed during the follow-up period in 12. Seven patients presented with preoperative hemipa- resis or quadriparesis. Six of these patients recovered completely and one had recovered partially at the last follow-up examination. All five patients with preop- erative cerebellar deficits had complete resolution (Table 4). Two patients who sustained postoperative hemipa- resis and one who sustained postoperative quadripa- resis had complete resolution of their deficits (Table 5). One patient who sustained a postoperative quadri- paresis (Case 16) experienced moderate recovery and could walk with minimal assistance prior to his death from pneumonia. Another patient with postoperative hemiplegia (Case 8) showed moderate initial improve- ment but subsequently deteriorated because of tumor regrowth. Either one-third or one-half of the occipital condyle was removed in seven patients with intradural tumors in the foramen magnum area. None required postop- erative fusion. On the other hand, complete resection of the occipital condyle was performed in seven pa- 56 tients with extradural lesions, six of whom underwent occipitocervical fusion with instrumentation and bone grafts. In two of these patients with chordomas, both occipital condyles were resected in a staged fashion. Complications CSF Leakage. Four patients suffered CSF leakage through the wound or a pseudomeningocele. In two of these patients the leak resolved with lumbar drainage. In the other two patients, who also had communicat- ing hydrocephalus, a ventriculoperitoneal shunt was eventually required. One of these also required a wound revision and closure of the dura with a fascia lata graft. In general, the problem of CSF leakage has declined during our recent experience. We try to leave a cuff of dura around the vertebral artery and subsequently use it to achieve watertight closure if the dura is not involved by tumor. When the dura is resected because of tumor involvement, a fascia lata graft and fibrin glue, in addition to reapproximation of the muscle lay- ers as Closely as possible, are recommended. In patients undergoing reoperation, we routinely use postoperative lumbar CSF drainage. If the dural closure is tenuous, CSF drainage is also instituted. Wound Infection. Despite previous operations and ra- diation therapy, only one patient developed a wound infection. The infection was considered to be iatrogeni- cally related to a lumbar drain, meningitis, and pseudo- J. Neurosurg. / Volume 81 / July, 1994 Lateral transcondylar approach 4 ( J Fic. 7. Case 2. Upper: Computerized tomography scan with sagittal reconstruction of the cervicomedullary area showing basilar invagination. Lower; Vertebral angiogram showing severe stretching and narrowing of the contralateral vertebral artery and occlusion of the ipsilateral artery. meningocele, and it eventually resolved after a wound revision and antibiotic therapy. The use of perioperative antibiotic prophylaxis and vascularized tissue to cover the surgical defect helps prevent infection. We use sharp dissection of the muscle planes without employing electrocautery, we keep the muscles moist, and we avoid over-retraction to prevent severe injury. If the patient has muscle atrophy or scarring from prior surgery, a rotation flap or a free flap may occasionally be needed for recon- struction. Vertebral Artery Injury. Four patients sustained in- traoperative injury to the vertebral artery, which was successfully repaired in three. However, one patient subsequently developed a pseudoaneurysm distal to the site of repair that required occlusion. Three of the four patients exhibited pathological involvement of the ar- tery preoperatively. The first patient (Case 16) was a 48-year-old man who had undergone two prior operations for clivus/ foramen magnum meningioma and presented with symptomatic regrowth of the tumor. At surgery, the ip- silateral vertebral artery was found to be abnormal in the extradural segment, with a scarred wall and poor pulse. Both vertebral arteries and the anterior spinal arteries were tumor-encased intradurally. They were dissected free but tumor was left against the spinome- dullary junction area because of a poor arachnoidal plane. During surgery, the artery was retracted to enable resection of the tumor. The patient awoke with mild hemiparesis postoperatively, which progressed to quadriparesis. Postoperative arteriography revealed oc- clusion of the vertebral artery. The patient underwent reoperation, and a vein graft reconstruction of the oc- cluded artery was attempted. However, we could not J. Neurosurg. / Volume 81 / July, 1994 -_ a4 Fic. 8. Case 2. Left: Arteriogram showing normal ap- pearance of the vertebral artery after reconstruction. Right: Arteriogram demonstrating a pseudoaneurysm that developed from the artery beyond the site of anastomosis. The aneurysm could be trapped because the other artery had normalized in position and considerably enlarged in caliber. readily find a distal segment of the artery that was ac- cessible beyond the occlusion site. The patient’s post- operative course was complicated by meningitis and wound infection. He was making a gradual recovery and was able to walk with minimal assistance; however, he died of aspiration pneumonia 8 months after the op- eration. In this case, aggressive retraction of a previ- ously abnormal vertebral artery was thought to be the cause of postoperative occlusion. In the second patient (Case 15), the vertebral artery was injured during extradural exposure, at the point where it turned sharply around the lateral mass of C-1. This small laceration was easily repaired after tempo- rary trapping. The third patient (Case 21) harbored a glomus jugulare tumor. His vertebral artery was totally encased by tumor and scar tissue from five prior op- erations and radiotherapy. The artery was injured early in the tumor dissection. However, after the tumor was resected, the lower end of the artery was mobilized from the C-3 foramen upward and was reconstructed by direct anastomosis. Postoperative arteriography and follow-up arteriography 1 year later revealed a patent artery. The fourth patient (Case 2) had rheumatoid arthritis and severe basilar invagination (Fig. 7 upper). Resec- tion of the odontoid process via an extreme lateral oc- cipitocervical fusion was carried out. However, she developed progressive quadriparesis postoperatively, requiring re-exploration and removal of the fusion, laminectomy of C-2, and partial resection of the oc- cipital bone. During the second operation, the vertebral artery was injured at the level of the C-2 foramen, and an attempt to seal the hole with bipolar cautery resulted in enlargement of the hole. Primary repair of the artery with 8—0 nylon sutures was performed but resulted in 57 arterial occlusion (Fig. 7 /ower). Although the patient’s quadriparesis improved dramatically, a third operation was undertaken. The thrombosed segment of the artery was excised and repaired by anastomosis because the contralateral artery was severely narrowed. A postop- erative arteriogram showed patency of the artery (Fig. 8 left). However, 3 months postoperatively she devel- oped a pseudoaneurysm of the artery (Fig. 8 right) and delayed facial paralysis. Since the contralateral artery had significantly enlarged and was normal by this time, the pseudoaneurysm was explored and the vertebral artery trapped. At surgery, the pseudoaneurysm was discovered to have originated 1 cm distal to the site of prior anastomosis, just proximal to the posterior in- ferior cerebellar artery. It is likely that the artery, which was already abnormal, was weakened further by the thrombosis or by the temporary clip, leading to the de- layed formation of a pseudoaneurysm. This patient subsequently made a complete neurological recovery. Since the extreme lateral transcondylar approach re- quires considerable mobilization of the vertebral artery, several precautions are required to avoid arterial injury. A high degree of knowledge and skill developed by performing cadaver dissections is required. Dissection of the artery must be performed under a surgical mi- croscope. When bleeding from the venous plexus is en- countered, it can be stopped with an irrigating bipolar cautery or by gentle packing with rolls of Surgicel; overpacking inside the bone canal must be avoided. When the artery is injured, one should perform primary repair or, if this is not possible, vein graft reconstruc- tion. If occlusion of the vertebral artery is detected postoperatively, the question of whether to re-explore and repair the vessel is a difficult one. We favor re- operation if the artery is dominant or has few collateral branches, or if the patient has neurological symptoms. Cranial Nerve Palsy. The nerves at greatest risk for injury during surgery via the extreme lateral transcon- dylar approach are the 12th cranial nerve bilaterally, and the ipsilateral 9th, 10th, and 11th cranial nerves. We have found that intraoperative monitoring of the 10th through 12th cranial nerves is very useful in re- ducing injuries. When a nerve is obviously transected at surgery, an immediate reconstruction is recom- mended. This was performed in Case 10 for the seventh cranial nerve and in Case 6 for the ninth and 10th cra- nial nerves. The patient with facial nerve repair (Case 10) made a significant recovery. The other patient died 3 months postoperatively, before adequate follow-up time was available to assess recovery. Condyle Resection. When the entire occipital con- dyle is resected, occipitocervical fusion is necessary. One patient (Case 13) in whom fusion was not initially performed required a delayed occipitocervical fusion. Partial resection of the occipital condyle does not re- quire a fusion procedure. Discussion Surgical management of lesions in the region of the lower clivus, foramen magnum, and upper cervical ver- 58 R. P. Babu, L. N. Sekhar, and D. C. Wright tebrae has been a difficult task until recently. A bilateral or unilateral suboccipital approach with cervical lam- inectomy has been the favored treatment for intradural lesions of this area, but the surgical results were dis- appointing for anteriorly placed lesions with posterior displacement of the spinomedullary junction.2%'5'6 Heros* described a very lateral suboccipital approach for vertebral and vertebrobasilar artery lesions, empha- sizing the radical removal of bone in the foramen mag- num area but not including the occipital condyle. In 1978, Seeger" described partial resection of the oc- cipital condyle in an approach to the ventral surface of the medulla oblongata. Koos, et ai.,’ more recently reported increased exposure of the lower clivus and rim of the anterior foramen magnum but did not remove the occipital condyle. In 1987, Gilsbach, et al.,> de- scribed drilling the lateral portion of the arch of C-1, the laterobasal occiput, and the medial portion of the atlanto-occipital joint. They also performed stabilizing procedures between the atlas and occiput. A similar procedure with some modifications has been used by our group since 1985.!'3 George, et al.,? mobilized the vertebral artery from C-2 to the dural entrance point and sectioned the sigmoid sinus but did not remove the occipital condyle. Spetzler and Grahm'* and Berta- lanffy and Seeger! mobilized the vertebral artery from C-1 to the dural entrance point in addition to drilling away the C-1 facet, posterior arch, and posterior lateral third of the occipital condyle. Pemeczky” drilled the jug- ular tubercle while treating vertebral artery or verte- brobasilar junction aneurysms through a posterolateral approach. Necessity of the Transcondylar Approach The development of any new approach may lead to its overuse by less experienced surgeons. The transcon- dylar approach is absolutely essential for intradural mass lesions located ventral to the spinomedullary junction, but is not necessary for laterally placed le- sions, which can be removed by traditional approaches. The extent of occipital condyle resection can be varied according to the needs of the particular case. Extradural tumors involving the lower clivus or the occipital condyle/jugular foramen area are ideal for exposure via the transcondylar approach. For developmental and rheumatoid lesions in which the vertebral artery is sig- nificantly involved, the transcondylar or transfacetal approach should be selected. For giant vertebral artery aneurysms, vertebrobasilar junction aneurysms, and ar- teriovenous malformations located anteriorly near the midline, the transcondylar approach is optimum. Ar- teriovenous fistulae involving the vertebral artery can be managed by a transfacetal approach when standard interventional procedures are unsuccessful. Disadvantages of the Transcondylar Approach The disadvantages of the transcondylar approach are the potential for vertebral artery injury, CSF leakage, and cranial nerve injury. In this series, a number of the vertebral artery exposures were performed in a training situation. Only one injury occurred during exposure of J. Neurosurg. / Volume 81 / July, 1994 Lateral transcondylar approach anormal artery and it was easily repaired. The remain- ing three vertebral arteries injured were already abnor- mal because of the disease process or prior treatment. Two of these were successfully repaired. Much caution and skill are needed in such situations and in cases in which the vertebral artery is markedly dominant. The risk of CSF leakage with the transcondylar approach may be slightly greater for intradurally ap- proached lesions than that with a midline posterior ap- proach because the abnormal dura mater is not resected after a midline approach. Using proper precautions, the risk of CSF leakage can be greatly minimized. The risk of cranial nerve injuries during resection of intradural lesions is probably the same as that with the lateral and posterior midline approaches. However, the transcondylar approach improves the chance for re- construction in the event of injury because the extra- dural portion of the nerve can be exposed. For extradural lesions, midline anterior approaches such as the transoral, transmandibular, or transmaxil- lary approaches have a lower risk of cranial nerve in- juries. However, these approaches have a limited lateral reach near the foramen magnum area and do not allow the surgeon to expose the vertebral artery and control it. Additionally, exposure of the vertebral artery via the transpharyngeal approach increases the risk of poten- tially fatal inflammatory arteritis and arterial rupture. Improvements of Surgical Technique The technical requirements described previously im- prove both the exposure obtained with the transcon- dylar approach and its safety. In addition, combina- tion with the subtemporal-infratemporal or presigmoid petrosal approach increases the range of lesions that can be treated and optimizes exposure for such lesions. The transcondylar approach can also be combined with anterior transpharyngeal approaches such as the trans- oral or transmaxillary route. However, in such cases 4 to 6 weeks should elapse between operations to pre- vent contamination of the lateral operative site with oropharyngeal flora. For extradural lesions, an anterior approach such as the transoral, transmandibular, or transmaxillary route should be considered as an alternative. Although these approaches have been used successfully for intradural lesions by some experienced surgeons, we do not rec- ommend them because of the great risk of CSF con- tamination and infection. Acknowledgments The authors thank Angela Jakary for preparing the manuscript, and Drs. Howard Yonas, Thomas Bertuccini, Hae Dong Jho, and William Donaldson for their roles in the management of some patients. Drs. Stephen Cass and Barry Hirsch assisted in some of the operations and Dr. Sunil Patel performed the cadaver dis- sections illustrated here. J, Neurosurg. / Volume 81 / July, 1994 References 1. Bertalanffy H, Seeger W: The dorsolateral, suboccipital, transcondylar approach to the lower clivus and anterior por- tion of the craniocervical junction. Neurosurgery 29: 815-821, 1991 2. George B, Dematons C, Cophignon J: Lateral approach to the anterior portion of the foramen magnum. Application to surgical removal of 14 benign tumors: technical note. Surg Neurol 29:484-490, 1988 3. Gilsbach JM, Eggert HR, Seeger W: The dorsolateral ap- proach in ventrolateral craniospinal lesions, in Voth D, Glees P (eds): Diseases in the Cranio-Cervical Junction. Berlin: Walter de Gruyter, 1987, pp 359-364 4. Heros RC: Lateral suboccipital approach for vertebral and vertebrobasilar artery lesions. J Neurosurg 64:559-562, 1986 5. Iwai Y, Sekhar LN, Goel A, et al: Vein graft replacement of the distal vertebral artery. Acta Neurochir 120:81-87, 1993 6. Karnofsky DA, Burchenal JH: The clinical evaluation of chemotherapeutic agents in cancer, in MacLeod CM (ed): Evaluation of Chemotherapeutic Agents. New York: Co- lumbia University Press, 1949, pp 191-205 7. Koos WTH, Spetzler RF, Pendl G, et al: Color Atlas of Microneurosurgery. New York: Thieme-Stratton, 1985, pp 125-134 8. Love JG, Adson AW; Tumors of the foramen magnum. Trans Am Neurol Assoc:78-80, 1941 9. Meyer FB, Ebersold MJ, Reese DF: Benign tumors of the foramen magnum. J Neurosurg 61:136-142, 1984 10. Perneczky A: The posterolateral approach to the foramen magnum, in Samii M (ed): Surgery In and Around the Brain Stem and the Third Ventricle. Berlin: Springer- Verlag, 1986, pp 460-466 11. Seeger W: Atlas of Topographical Anatomy of the Brain and Surrounding Structures. Wien: Springer-Verlag, 1978, pp 486-489 12. Sen CN, Sekhar LN: An extreme lateral approach to intra- dural lesions of the cervical spine and foramen magnum. Neurosurgery 27:197-204, 1990 13. Sen CN, Sekhar LN: Surgical management of anteriorly placed lesions at the craniocervical junction — an alterna- tive approach. Acta Neurochir 108:70-77, 1991 14. Spetzler RF, Grahm TW: The far-lateral approach to the in- ferior clivus and the upper cervical region: technical note. Barrow Neurol Inst Q 6(4):35-38, 1990 15. Stein BM, Leeds NE, Taveras JM, et al: Meningiomas of the foramen magnum. J Neurosurg 20:740-751, 1963 16. Yasargil MG, Mortara RW, Curcic M: Meningiomas of basal posterior cranial fossa. Adv Tech Stand Neurosurg 7:1-115, 1983 Manuscript received May 19, 1993. Accepted in final form January 11, 1994. Address for Dr. Babu: Department of Neurosurgery, Univer- sity of Pittsburgh Medical Center, Pittsburgh, Pennsylvania. Address reprint requests to: Laligam N. Sekhar, M.D., De- partment of Neurological Surgery, George Washington Univer- sity Medical Center, 2150 Pennsylvania Avenue NW, Washing- ton, DC 20037. 59 SPR i. Gvelpltaliiiny un | Artery) aay. * . " - 1" . n . oe ilgnte; Occipital a . | ain: fi Pins