Total Excision of a Thalamic Arteriovenous Malformation Using an Orbito-Fronto-Malar Approach: Case Report Hajime Touho, M.D., Hideyuki Ohnishi, M.D., Jun Karasawa, M.D., Hiroyuki Nakase, M.D., Yasuharu Watabe, M.D., and Norihiko Furuoka, M.D. Department of Neurosurgery, Osaka Neurological Institute, Osaka, Japan Touho H, Ohnishi H, KarasawaJ, Nakase H, Watabe Y, Furuoka N. Total excision of a thalamic arteriovenousmalformation using an orbito-fronro-malar approach: case report. Surg Neurol 1994;42:297-302. A 37-year-old woman was admitted to Osaka Neurological Institute after the sudden onset of left hemiplegia, hemihypesthesia, and ipsilateral hemianopia on February 4, 1992. Computed tomography (CT) disclosed the presence of hemorrhage in the right thalamus extending to the ipsilateral internal capsule. Cerebral angiography after CT scanning disclosed the presence of a cerebral arteriovenous malformation (AVM) fed by copsulothalamic and lateral geniculate body arteries originating from the right anterior choroidal artery. She was operated on with removal of the AVM using a right orbito-fronto-malar approach (OFM approach), which did not require transection of the cerebral parenchyma. The anterior choroidal artery could be followed distally from its origin and small feeding branches originating from the parent artery were easily identified, and the cerebral base could be examined in greater detail than with the conventional frontotemporal approach. The nidus could be excised in its entirety without difficulty. Postoperative angiography confirmed total excision of the AVM. She was transferred to another hospital for rehabilitation on April 13, 1992. Motor strength on the left side had improved to 3 I 5 by that time. The OFM approach appears to be potentially useful for the resection of inferolateral thalamic AVMS, because it does not require corticotomy and feeding branches can be identified and dealt with prior to other surgical manipulations. KEY WORDS: Anterior choroidal artery; Orbito-fronto-malar approach; Surgery; Thalamic arteriovenous malformation the detection Address repvint requests to: Hajime Touho, M.D., Department of Neurosurgery, Osaka Neurological Institute, Shonai Takara-machi, Toyonaka, Osaka 561 Japan. Received August 23, 1993; accepted November 11, 1993. 0 1994by Elsevier Science Inc. malforma- scopic technique, resection of AVMs has become a routine procedure. However, resection of cerebral AVMs present in eloquent regions such as motor and/or speech cortex or deep cerebral hemisphere including the thalamic nucleus has generally been considered technically difficult due to the possibility of damage to critical structures [1,4,9]. Drake reported five such AVMs among 166 cases described (3%), four of which were located in the thalamus Cl]. Waga et al reported nine periventricular AVMs in a series of 70 cases (13%) 112). Malik et al also reported 10 thalamocaudate AVMs in a series of 200 (5%) patients who had undergone surgery IS]. If deep-seated AVMs they may have a higher other AVMs. of this kind are left untreated, incidence of rupture than do The rate of rebleeding is thought to be 6% during the first year after an initial episode of hemorrhage and subsequently returns to 2%-3%. When intraventricular and/or intracerebral hemorrhage occurs, the neurologic deficits come severe 167. However, surgery plicated minimal associated with such AVMs for these particular AVMs be- is com- by the need for adequate deep exposure with disruption of normal cortex, and by the fact that they are surrounded by eloquent regions of the brain. Whether AVMs in the thalamic region are surgically accessible is a subject of controversy. In this report, we describe the complete resection of a thalamic AVM using an orbito-fronto-malar approach [8]. There were no neurologic Case Recent advances in magnetic resonance imaging (MRI) and digital subtraction angiography (DSA) have enabled of many cerebral arteriovenous tions (AVMs) during routine work-up prior to rupture. In addition, due to improvements in surgical micro- complications. Report A 37-year-old woman was admitted to our institution after the sudden onset of left hemipalsy while playing with her child on February 4, 1992. Left hemiplegia, hemihypesthesia, and ipsilateral hemianopia were noted at admission. The patient’s neck was not stiff. her blood pressure was 150/90 mm Hg. Computed tomography 0090-3019194117.00 298 Figure Surg Neurol 1994;42:297-302 1. Computed tomgrapby Touho scam on admission demmtrated a high hnsity et al lesion in the right tbalamus. Figure 2. Angiograms of the right zntwnal cavottd artery disclosed a cerebral arteriovenous malfirmation fed by small bvanrbes originating from the right anterior cboroidaf artery. Thalamic AVM and Orbito-Fronto-Malar Approach Surg Neural 1994;42:297-302 299 Figure 3. Magnetic resonance zmaging studies obtained 7 days after the onset dzsclosed a j&w-void lesion located in the Tight lateral geniculate boLy surrounded by a hematoma containing primarily methohemoglobin and pevifocal edema. (upper) T,-weighted image (TR: 600 I TE: 251, (lower) T,-weighted image (TR: 2500 I TE: 100). (CT) scans obtained of a region of on admission high density extending to the ipsilateral Selective cerebral scanning, and detected disclosed in the internal angiography the presence right capsule (Figure was performed a cerebral thalamus AVM 1). after CT fed by capsu- lothalamic and lateral geniculate body arteries originating from the right anterior choroidal artery as superomedial branches [14]. A vein at the ipsilateral temporal base and the ipsilateral to have become draining veins. basal vein were noted The diameter of the nidus was approximately 2 ems (Figure 2). The patient was alert despite her left hemiplegia, hemihypesthesia, and hemianopia and was treated in a conservative fashion. MRI studies obtained 7 days after the onset of hemorrhage disclosed that a flow-void lesion located in the right lateral geniculate body was surrounded by a region of respectively high and low signal intensities images. This on region T,-weighted was thought and T,-weighted to correspond to a hematoma containing primarily methohemoglobin. Perifocal edema was observed surrounding the hematoma (Figure 3). Operation On February 20, 1992, the patient underwent surgery, with removal of the AVM using a right orbito-frontomalar (OFM) approach ES}. A right frontotemporal skin incision was made, and frontotemporal craniotomy was was performed (Figure 4 A). A temporal craniectomy then performed (Figure 4 B). The fascia of the temporal muscle was torn off subfascially from the superolateral orbital edge and zygomatic bone. Orbito-zygomatic osteotomy was performed (malar flap) (Figure 4 C). The Touho et al Surg Neural 1994;42:297-302 AChr \ periorbital A fat \‘VSylvian veins Figure 5. Schematic representation of the intraopwative findings is shown. The right anterior choroidzl army (AChr A) gives small feeding arteries penetrating the right latwal geniculate body, and draining vein at the ipsilatwal temporal base is noted. Figure 4. Right o&to-fronto-malar approach is shown. (A) frontotemporal craniotomy; (B) temporal craniectomy, (C) ovbito-zygomuticosteotonay. orbital bone was removed in the direction of the anterior clinoid pletely process, so that and the latter was drilled the internal carotid artery moved inward without difficulty. Under out comcould be disappearance of mass effect (Figure 6). In angiographic studies of the right internal carotid and the vertebral arteries 2 weeks after surgery, the nidus was no longer seen, and the AVM appeared removed in its entirety (Figure 7). performed to have been microscopic observation, the right internal carotid artery was moved medially, and the anterior choroidal artery was identi- Discussion fied and followed distally. At the same time, the ipsilateral optic nerve was traced back to the optic tract. In The diagnosis of deep-seated AVMs, thalamic AVMs, has required both the cisternal segment of the anterior choroidal artery, the feeding branches of the AVM were found penetrating into the lateral geniculate body (Figure 5). A small incision was made on the inferior surface of the lateral geniculate body, and the hematoma surrounding the AVM was aspirated. The small feeding arteries were electrocoagulated and cut. One of the draining veins running along the temporal base laterally was identified and cut (Figure 5). Finally, the remaining medial draining vein was electrocoagulated and cut, after which the nidus could be removed Postoperative in its entirety. Course The condition of the patient remained unchanged during the first few weeks after surgery. Slow improvement was noted in the neurologic condition of her left extremities thereafter, and motor strength on the left side was 315 at the time of transfer to another hospital for rehabilitation on April 13, 1992. CT scans obtained the day after surgery confirmed total removal of the hematoma and also demonstrated including traditional that of radio- graphic techniques and more recently developed ing techniques. These lesions are studied initially imagusing plain / contrast-enhanced CT scanning that can disclose deep hemispheric abnormalities, particularly when a hemorrhagic accident responsible for the abnormality has occurred within the past few days. Four-vessel cerebral angiography, however, is the mainstay of radiologic evaluation of lesions of this type. It can be used to obtain information regarding the location of the nidus, as well as its feeding and drainage systems. Preoperative grading can be performed using the criteria described by Spetzler et al {Ill. Recently, noninvasive has also become available magnetic resonance imaging for evaluation of these lesions and can be used to demonstrate the location of the nidus in relation to nearby landmarks. Because they are uncommon, the natural history of these lesions is not well understood. If left untreated, 2%-3% will bleed per year, and thalamic AVMs may well have a higher incidence of rupture than superficially located AVMs [2,6,9]. Thalamic Figure AVM and Orbito-Fronto-Malar Approach Surg Neural 1994;42:297-302 301 6. Computedtomography scans obtained the day after surgery confirmed total removal of the hematoma. Figure 7. Angiograms of tht : right internal ran zid arty 2 ueeh ,tifter urgq disclosed tba ‘t the nidus waJ no longer obseruable. Surg Neural 1994;42:297-302 302 Touho et al If the nidus can be reached surgically without serious damage to the brain itself, and if it is relatively small, it should be treated surgically with the aim of total resection. The surgical approach used is one of three kinds: (1) transcortical, (2) transcortical-transventricular, or (3) interhemispheric [1,3,7,10,13,14]. Each has its own unique applications that depend extent of the nidus, e.g., ventricular system or not. For resection of posterior hemispheric approach a straight upon the location whether thalamic for exposure, The semisitting but into AVMs, and the the inter- is used, with the patient prone or three-quarters down position. it extends in either prone, operated-side- position has been used it may prove uncomfortable for the surgeon and carries the risk of venous air embolism. The transcortical-transventricular been used for resection approaches approach has AVMs. Similar surgical of anterior thalamic of thalamic can be used for resection also AVMs. An interhemispheric or transcortical transventricular approach can be used for lesions. Injury to the fornix and/or frontal lobe with hemiparesis phasia remains as a significant cular approach cannot this report, orbito-fronto-malar nidus located and/or dys- The transventri- be used when visible from the ventricular In danger. the nidus is not side. we have described approach for surgical in the lateral geniculate this approach did not require transection the parent (the use of an excision body [S]. parenchyma; artery the of a Use of of the cerebral anterior choroidal artery) could be followed distally from its origin and the References 1. Drake CG. Cerebral arteriovenous malformations: considerations for an experience with surgical treatment in 166 cases. Clin Neurosurg 1979;26:145-208. 2. Graf CJ, Perret GE, Tormer JC. Bleeding from cerebral arteriovenous malformations as part of their natural history. J Neurosurg 1983;53:331-7. 3. Kunc 2. Deep seated arteriovenous malformations: a critical review. In: Carrea R, ed. Neurological surgery, with special emphasis on noninvasive methods of diagnosis and treatment. Amsterdam: Excerpta Medica, 1978:188-93. 4. Lussenhop AJ, Gennarelli TA. Anatomical grading of supratentorial arteriovenous malformations Neurosurgery 1977;1:30-5. for determining operability. 5. Malik GM, Vmansky F, Pate1 S, Ausman JI. Microsurgical removal of arteriovenous malformations of the basal ganglia. Neurosurgery 1988;23:209-17. 6. Malik GM, McCormick PW. Surgical resection of thalamocaudate arteriovenous malformations. In: Wilkins RH, Rengachary SS, eds. Neurosurgery update II. Vascular, spinal, pediatric, and functional neurosurgery. New York: McGraw-Hill, 1991:14956. 7. Nehls DG, Marano SR, Spetzler RF. Transcallosal approach to the contralateral ventricle. J Neurosurg 1985;62:304-6. 8. Ohnishi H, Karasawa J. Surgical approaches for tumors involving the cavernous sinus. Neurosurgeons (Proceedings of the Japanese Congress of Neurological Surgeons) (Japanese) 1992;11:208-19. 9. Pellettieri L, Carlsson CA, Grevsten S, Norlen G, Uhlemann C. Surgical vetsus conservative treatment of intracranial anteriovenous malformations. A study in surgical decision-making. Acta Neurochir (Wien) 1980;Suppl 29:1-86. 10. Solomon RA, Stein BM. Interhemispheric approach for the surgical removal of thalamocaudate arteriovenous malformations. J Neurosurg 1987;66:345-51. it were easily 11. Spetzler RF, Martin NA. A proposed grading system for arteriovenous malformations. J Neurosurg 1986;65:476-83. identified. examined Using this approach, the cerebral base can be more closely than if the conventional fronto- 12. Waga S, Shimosaka S, Kojima T. Arteriovenous malformations of the lateral ventricle. J Neurosurg 1985;63:185-92. temporal approach 13. Yasargil MG, Jain KK, Antic J, Laciga R. Arteriovenous malformations of the splenium of the corpus callosum: microsurgical treatment. Surg Neural 1976;5:5-14. small feeding superolateral arteries orbital originating from is used, as it includes removal of the edge. This approach appears to be potentially resection of inferolateral thalamic AVMs useful for the because it re- quires neither frontal nor temporal lobe corticotomy, and feeding arteries can be identified and dealt with prior to other surgical manipulations. 14. Yasargil MG. Deep central AVMs. In: Yasargil MG, ed. Microneurosurgery. BIB. AVM of the brain, clinical considerations, general and special operative techniques, surgical results, nonoperated cases, cavernous and venous angioma, neuroanesthesia. Stuttgart-New York: George Thieme Verlag, Thieme Medical Publishers, 1988:204-368.