Traumatic Chiasmal Syndrome Associated With Midline Basilar Skull Fractures Grant W. H e i n z , M.D., W i l l i a m R. N u n e r y , M.D., and C. Barrie Grossman, M.D. We studied two young males who had visual field defects consistent with optic chiasmal injury after blunt frontal head trauma. One patient also had a unilateral optic neuropathy. Long-term follow-up disclosed complete bitemporal hemianopsias in these patients. Both patients had midline basilar skull frac­ tures that traversed the midclivus through the sella turcica floor, dorsum sellae, and sphe­ noid sinus. Magnetic resonance images did not identify intrachiasmal hemorrhage as the cause of the visual field defect. We believe this fracture pattern, in conjunction with the mag­ netic resonance image findings, suggests tear­ ing of the optic chiasm on a microscopic, if not macroscopic, scale as the cause of the com­ plete bitemporal hemianopsia. TRAUMATIC CHIASMAL SYNDROME is a rare con­ dition manifested by the onset of a bitemporal hemianopsia after head trauma, usually frontal. Since its recognition in 1883 by Nieden 1 ap­ proximately 100 cases have been reported. 2,3 Multiple mechanisms for injury to the optic chiasm that result in bitemporal hemianopsia have been proposed. These proposed mecha­ nisms include chiasmal infarction, 4,5 compressive injury from intrachiasmal hemorrhage, 6,7 and direct tearing or stretching of the chiasm.8"11 We studied two cases of traumatic chiasmal syndrome with computed tomographic and magnetic resonance images. Accepted for publication Sept. 8, 1993. From the Division of Oculoplastic Surgery, King Khaled Eye Specialist Hospital, Riyadh, Saudi Arabia (Dr. Heinz); the Department of Ophthalmology, Indiana University, Indianapolis, Indiana (Dr. Nunery); and the Department of Radiology, Methodist Hospital and Indi­ ana University, Indianapolis, Indiana (Dr. Grossman). Reprint requests to Grant W. Heinz, M.D., c/o Medical Library, King Khaled Eye Specialist Hospital, P.O. Box 7191, Riyadh 11462, Saudi Arabia. 90 Case Reports Case 1 A 21-year old man struck his forehead after being projected from an all-terrain vehicle. Ex­ amination disclosed a cerebral hemorrhage, basilar skull fracture, and LeFort II midfacial fracture with minimal displacement. Twelve days after the injury, his mental status improved and he complained of decreased vi­ sion in his left eye and decreased hearing in his right ear. This complaint prompted the first ophthalmic examination since the accident. Visual acuity without correction was R.E.: 2 0 / 20 and L.E.: 20/200 with eccentric fixation in his nasal field. A relative afferent pupillary defect was noted in the left eye. Ocular motility was full and facial nerve function was intact bilaterally. He had no enophthalmos, malocclusion, or midfacial hypermobility. Ophthalmoscopy demonstrated normal retinal perfu­ sion and no pallor or edema of the optic nerve head. The patient was treated with intravenous methylprednisolone, 1 g, every six hours for 72 hours. Goldmann visual field testing, before corticosteroid administration, demonstrated a left na­ sal island and a complete right temporal hemi­ anopsia (Fig. 1). Audiometry demonstrated a profound right sensorineural hearing loss. Computed tomography (Fig. 2) demonstrated a longitudinal midclival fracture that traversed the clivus, sella turcica floor, and tuberculum sellae. No optic nerve canal fractures were noted. A LeFort II fracture with comminuted maxillary fractures and a minimally telescoped nasoethmoid fracture were present. Magnetic resonance imaging (Fig. 3) demonstrated a swollen optic chiasm located just beneath a right-sided hypothalamic hemorrhagic contu­ sion. The hemorrhage also involved the gyrus rectus of the frontal lobe. Hemorrhage was also seen in the sphenoid sinus and along the tentorium. ©AMERICAN JOURNAL OF OPHTHALMOLOGY 117:90-96, JANUARY, 1994 Traumatic Chiasmal Syndrome and Basilar Fracture Vol. 117, No. 1 120 105 90 75 60 120 105 90 75 91 60 345 255 270 RIGHT Fig. 1 (Heinz, Nunery, and Grossman). Left nasal island and a complete right temporal hemianopsia. Visual acuity is L.E.: 20/200 and R.E.: 20/20. Nine months after the injury visual acuity was R.E.: 20/20 and L.E.: 20/20. The left rela­ tive afferent pupillary defect had resolved. There was bilateral optic nerve pallor distribut­ ed in a band distribution. No extraocular mus­ cle restriction or diplopia, enophthalmos, malocclusion, or midfacial flattening were noted. Goldmann visual field examination demon­ strated complete bitemporal hemianopsia (Fig. 4). Case 2 A 15-year-old boy, who had been an unre­ strained driver in a motor vehicle accident, sustained a frontal head impact. When we ex­ amined him five days after the injury, he denied any visual problems. Visual acuity was 20/20 in both eyes with no afferent pupillary defect present. Confronta­ tional visual field demonstrated a bitemporal hemianopsia; slit-lamp examination disclosed Fig. 2 (Heinz, Nunery, and Grossman). Left, Axial computed tomography scan slices at the clivus level, and right, at the sella turcica level. A midclival fracture (arrows) longitudinally traverses the clivus, sella turcica floor, and tuberculum sellae. Comminuted maxillary and ethmoid fractures are also present. 92 January, 1994 AMERICAN JOURNAL OF OPHTHALMOLOGY Fig. 3 (Heinz, Nunery, and Grossman). Top left, Sagittal; top right, axial; and bottom left, pituitary level coronal magnetic resonance Τ,-weighted scans. The swollen optic chiasm (OCh) is seen just beneath the right-sided hyperintensive hypothalamic hemorrhagic contusion. The hemorrhage methemoglobin (Mh) content is responsible for the T, bright signal. The hemorrhage is shown involving the frontal lobe gyrus rectus on the sagittal sequence. There is hem­ orrhage in the sphenoid sinus (SpS) and along the tentorium (T). The pituitary gland (P) is seen adja­ cent to the swollen optic chiasm. The infundibular stalk is obscured. bilateral subconjunctival hemorrhages; and in­ direct ophthalmoscopy demonstrated normal retinal perfusion and no pallor of the optic nerve head. Goldmann visual field examination demonstrated a complete bitemporal hemi­ anopsia (Fig. 5). Computed tomography (Fig. 6) disclosed a sagittally oriented fracture that traversed the midclivus, through the sella turcica floor and sphenoid sinus, through the planum sphenoidale and dorsum sellae. A swollen optic chiasm was seen on magnetic resonance imag­ ing (Fig. 7). Traumatic chiasmal syndrome was diag­ nosed. Cerebrospinal fluid rhinorrhea persisted ten days after injury. The patient developed meningitis, which was culture-positive for Staphylococcus aureus and was treated effective­ ly with intravenous antibiotics. Diabetes insipidus was noted and resolved within three weeks after the injury. Six months later, his visual acuity remained 20/20 in both eyes. The bitemporal hemianop­ sia had not improved. Bilateral optic atrophy had developed in a band distribution. Discussion Traumatic chiasmal syndrome is diagnosed by an immediate bitemporal hemianopsia after head trauma. The bitemporal visual field loss may be partial, but complete bitemporal hemi­ anopsia is common. 712 Complete bitemporal hemianopsia is rarely seen except after trau­ ma.12 Compressive lesions of the chiasm more likely produce relative bitemporal hemianop­ sia.12 Laursen, 7 in 1971, reported that 60% of pa­ tients with traumatic chiasmal syndrome had complete bitemporal hemianopsias. Other in- Traumatic Chiasmal Syndrome and Basilar Fracture Vol. 117, No. 1 120 105 90 75 60 120 105 ÇQ 75 93 60 345 240 255 270 235 300 240 255 LEFT 270 235 300 RIGHT Fig. 4 (Heinz, Nunery, and Grossman). Complete bitemporal hemianopsia. Visual acuity is 20/20 in both eyes. vestigators 6 had similar findings. Both our pa­ tients had complete bitemporal hemianopsias. The combination of optic neuropathy and contralateral chiasmal injury was noted by Duke-Elder and others.4'6·7·13 One of our patients (Case 1) initially had a complete right temporal hemianopsia and left optic neuropathy with a 240 255 270 LEFT 285 300 small nasal island of vision. Over the next three months, the optic neuropathy completely re­ solved, disclosing complete bitemporal hemi­ anopsia. Traumatic chiasmal syndrome may be noted either in isolation or associated with other neu­ rologic signs and symptoms. Associated find- 240 255 270 285 300 RIGHT Fig. 5 (Heinz, Nunery, and Grossman). Complete bitemporal hemianopsia. Visual acuity is 20/20 in both eyes. 94 AMERICAN JOURNAL OF OPHTHALMOLOGY January, 1994 Fig. 6 (Heinz, Nunery, and Grossman). Top left, Coronal clivus level; top right, sella turcica-sphenoid sinus level; bottom left, axial sella turcica floor; and bottom right, planum sphenoidal level computed tomographic scans. The fracture traverses the midclivus through the sella turcica floor and sphenoid sinus through the planum sphenoid (arrows). The optic canals are not involved. ings result from damage to structures in the region of the anterior cranial fossa or base of the skull. These include diabetes insipidus, anosmia, cranial nerve defects (II, III, IV, V, VI, VII), deafness (VIII), cerebrospinal fluid rhinorrhea and otorrhea, carotid aneurysm, carotid cavernous fistula, meningitis, panhypopituitarism, intrasellar hematoma, and pneumatocele.6 Diabetes insipidus occurred in both our cases and resolved within three weeks. Similarly, seven of the 11 patients with traumatic chiasmal syndrome described by Savino, Claser, and Schatz 6 developed diabetes insipidus, which resolved spontaneously. Sensorineural hearing loss from eighth cranial nerve injury was found in our first case, whereas cerebrospinal fluid leak and meningitis occurred in the second case. Traumatic chiasmal syndrome may also be associated with cranial fractures and prolonged loss of consciousness. 3,7 Altered mental status may delay recognition of the bitemporal hemianopsia, especially when the patient retains central vision. 4 Neither of our patients com­ plained of visual field defects until it was dem­ onstrated on examination, although the first patient (Case 1) recognized his neuropathic visual loss in the left eye. The cause of traumatic chiasmal syndrome has inspired speculation. The possibility of chi­ asmal infarction as a cause of traumatic bitem- Vol. 117, No. 1 Traumatic Chiasmal Syndrome and Basilar Fracture 95 Fig. 7 (Heinz, Nunery, and Grossman). Left, Sagittal; and right, pituitary level coronal magnetic resonance scans. The optic chiasm (OCh) is swollen and is seen closely abutting the infundibular stalk (I) and the sagittal images. poral hemianopsia 4,5 became less attractive when the rich anastomotic and multiple blood supply to the chiasm was demonstrated. 14 Intrachiasmal compressive hemorrhage dam­ aging chiasmal crossing fibers within the noncompliant durai covering6·7 may also be unlikely in view of the relative sparing of uncrossed fibers, as seen in most patients with traumatic chiasmal syndrome. Crompton 15 performed au­ topsies on 84 patients with histories of anterior visual pathway injury, and found that of the 16 patients with chiasmal injury, none had hemor­ rhages in the chiasm consistent with compres­ sion or loss of vision. They attributed vision loss in these patients to shearing lesions of the nerve. Intrachiasmal hemorrhage could not be documented on computed tomography or mag­ netic resonance imaging in either patient, al­ though hemorrhage was seen in adjacent struc­ tures (Fig. 3). Sagittal tearing or stretching of the chiasm has been demonstrated at autopsy, and has long been held as a possible cause for traumatic chiasmal syndrome. 4 8 Logan and Gordon 16 de­ scribed a patient with traumatic chiasmal syn­ drome and facial and basilar skull fractures. On craniotomy, they noted a fracture of the planum sphenoid and a displaced tuberculum sellae with resultant stretching of the chiasm. They concluded that the sudden stretching of the chiasm may have caused the chiasmal injury. Coppez 9 and Osterberg 10 produced sagittal tearing of the chiasm with frontal head injury in cadaver studies. Gurdjian and Webster11 dem­ onstrated the force of a frontal blow is transmit­ ted to the spheno-orbital roof to the base of the skull in cadavers. This force then causes separa­ tion of the skull, in the midline, in a bilaterally outward direction with resultant fracturing of the clivus and sella turcica. Gurdjian and Web­ ster11 concluded that these shearing forces could be transmitted to the chiasm, resulting in preferential stretch injury to the crossing fibers. Rand 8 emphasized that with a separation of the optic foramina, the optic chiasmal fibers, being weaker than the optic nerves, tear first. In both of our cases, the precipitating trauma was blunt frontal head trauma. This mode of injury is consistent with Gurdjian and Web­ ster's theory on chiasmal injury 11 and is found in 73% to 96% of traumatic chiasmal syndrome patients.3·6·17 Computed tomography (Figs. 2 and 6) in both our cases demonstrated sagittal midline frac­ tures of the clivus and sella turcica, consistent with a midline separation of the skull. The ability of the clivus to separate widely at impact and then recoil is illustrated by the occasional occurrence of the vertebral or basilar arteries becoming trapped in these types of fractures, resulting in death. 1820 In 1988, Joslyn, Mrivis, and Markowitz 21 published five reports of sagit­ tal clivus fractures. They found no previous reports demonstrating computed tomography findings of these fractures. Four of five patients in their series died within 30 days of the injury. Our two cases demonstrate the sagittal nature of the clivus and sella turcica fractures in asso- 96 AMERICAN JOURNAL OF OPHTHALMOLOGY d a t i o n with complete bitemporal hemianopsias, a n d illustrate t h e c o m p u t e d t o m o g r a p h i c a n d m a g n e t i c r e s o n a n c e i m a g i n g findings a s s o ­ ciated w i t h the fractures. O u r cases suggest tearing or s t r e t c h i n g w i t h m i c r o t e a r i n g of t h e chiasmal crossing fibers as t h e m e c h a n i s m of injury. T h e m a g n e t i c r e s o n a n c e (Figs. 3 a n d 7) i m a g i n g in t h e s e cases is n o t c o n s i s t e n t w i t h i n t r a c h i a s m a l h e m o r r h a g e b e i n g the cause of chiasmal injury. This s y n d r o m e h a s n o t p r e v i o u s l y b e e n a s s o ­ ciated w i t h a distinctive p a t t e r n of basilar skull fracture, even t h o u g h G u r d j i a n a n d Webster's 1 1 studies p r e d i c t e d a fracture p a t t e r n similar to that found in our p a t i e n t s . We believe t h a t w i t h sagittal clivus a n d sella turcica fractures, t h e chiasm is torn o n a microscopic, if n o t m a c r o ­ scopic, scale w i t h d e v e l o p m e n t of a c o m p l e t e b i t e m p o r a l h e m i a n o p s i a . Traumatic c h i a s m a l s y n d r o m e , w i t h this u n i q u e fracture p a t t e r n , may occur m o r e frequently t h a n p r e v i o u s l y rec­ o g n i z e d b e c a u s e of an associated d e c r e a s e d level of c o n s c i o u s n e s s a n d h i g h m o r t a l i t y rate in this injury. References 1. Nieden, A.: Zur Casuistik der nacht traumat. Verletzungen' des Hirns umd Rückenmarks Auftre­ tenden Augenstorüngen. Arch. Augenheilkd. 12:30, 1883. 2. Resneck, J. D., and Lederman, I. R.: Traumatic chiasmal syndrome associated with pneumocephalus and sellar fracture. Am. J. Ophthalmol. 92:233, 1981. 3. Noble, M. J., and McFadzean, R.: Indirect injury to the optic nerves and optic chiasm. Neuro-ophthalmology 7:341, 1987. 4. Traquair, H. M., Dott, N. M., and Russell, W. R.: Traumatic lesions of the optic chiasma. Brain 58:398, 1935. 5. Hughes, E. B. U.: Injury to the optic-chiasmal junction. Br. J. Ophthalmol. 27:367, 1943. 6. Savino, P. J., Claser, J. S., and Schatz, N. J.: January, 1994 Traumatic chiasmal syndrome. Neurology 30:963, 1980. 7. Laursen, A. B.: Traumatic bitemporal hemi­ anopsia. Survey of the literature and report of a case. Acta Ophthalmol. 49:134, 1971. 8. Rand, C. W.: Chiasmal injury complicating frac­ ture of the skull. Bull. Los Angeles Neurol. Soc. 2:91, 1937. 9. Coppez, H.: Le mechanism des lesions du chi­ asm dans les fractures du crane. Arch. Ophtalmol. 46:705, 1929. 10. Osterberg, G.: Traumatic bitemporal hemi­ anopsia (sagittal tearing of the optic chiasm). Acta Ophthalmol. 16:466, 1938. 11. Gurdjian, E. S., and Webster, J. E.: Head Inju­ ries. Boston, Little Brown and Co., 1959, p. 90. 12. Miller, N. R.: Walsh and Hoyt's Clinical Neuro-ophthalmology, vol. 1. Baltimore, Williams and Wilkins, 1982, p. 121. 13. Duke-Elder, S., and Scott, G. I.: Neuro-ophthalmology. In Duke-Elder, S. (ed.): System of Oph­ thalmology, vol. 12. St. Louis, C. V. Mosby, 1971, p. 399. 14. François, J., Neetens, A., and Collette, J. M.: Vascularization of the optic pathway. Br. J. Ophthal­ mol. 42:65, 1958. 15. Crompton, M. R.: Visual lesions in closed head injury. Brain 93:785, 1970. 16. Logan, W. C , and Gordon, D. S.: Traumatic lesions of the optic chiasma. Br. J. Ophthalmol. 51:258, 1967. 17. Obenchain, T. G., Killeffer, F. A., and Stern, W. E.: Indirect injury of the optic nerves and chiasma with closed head injury. Report of three cases. Bull. Los Angeles Neurol. Soc. 38:13, 1973. 18. Loop, J. W., White, L. E., and Shaw, C. M.: Traumatic occlusion of the basilar artery within a clivus fracture. Radiology 83:36, 1964. 19. Lindenberg, R.: Incarceration of a vertebral artery in cleft of a longitudinal fracture of the skull. J. Neurosurg. 24:908, 1966. 20. Signs, W. P., Jr.: Incarceration of the basilar artery in a fracture of the clivus. J. Neurosurg. 28:588, 1968. 21. Joslyn, J. N., Mrivis, S. E., and Markowitz, B.: Complex fractures of the clivus. Diagnosis with CT and clinical outcome in 11 patients. Radiology 166:817, 1988.