Traumatic Chiasmal Syndrome - A Case Report

Traumatic chiasmal syndrome is a rare condition manifested by the onset of a bitemporal hemianopia after head trauma. Trauma is one of the rarer aetiologies of a bitemporal hemianopia. Few patients survive the severe impact required to damage the anatomically privileged optic chiasm. Those who do survive have usually sustained a variety of neuro-endocrine and neurological deficits in addition to the visual signs. Despite being described more than a century ago by Nieden, the mechanism of injury to the chiasm remains uncertain. We report a patient with bitemporal hemianopia and a additional transient left central scotoma following head injury. He had no other neurological deficits and no evidence of chiasmal damage on neurological imaging. *Corresponding author: Shveta Bansal, Department of Ophthalmology, Manchester Royal Eye Hospital,Oxford road, Manchester, m139WL, United Kingdom, E-mail: Shveta.bansal@[email protected] Received: June 01, 2012 Accepted: August 26, 2013 Published: August 30, 2013 Visual field examination using a Humphrey three zone 120.2 test demonstrated a complete bitemporal hemianopia and an additional left central scotoma (Figure 4). Magnetic resonance imaging demonstrated no evidence of any Introduction A seventeen year old man was taken to the emergency department following a road traffic accident. He was an unrestrained back seat passenger of a car which was travelling at approximately 40 miles per hour when it collided with a tree. He was unconscious on arrival and required immediate intubation and ventilation. He sustained multiple injuries with cerebro-spinal fluid (CSF) rhinorrhea, fractures of the face, skull and cervical spine and multiple lacerations over his face. A computed tomographic (CT) scan on admission revealed bifrontal contusions with presence of blood in the ventricular system, suprasellar fossa and pre-pontine cistern. There were extensive fractures of the facial bones, though clinically no mid-face instability was noted. He had fractures involving the frontal bones, maxilla, sphenoid, lateral wall and roof of the right orbit with fracture lines extending through the ethmoid bones (Figures 1-3). No bone fragments were noted to have been displaced into the brain matter and there was no evidence of chiasmal haemorrhage or compression. On recovering complete consciousness after a fortnight the patient complained of decreased vision in the left eye with diplopia for which an ophthalmic examination was requested. Visual acuity was 6/9 in the right eye and counting fingers in the left. The colour vision was found to be 13/17 plates in the right eye and unrecordable in the left eye using Ishihara colour plates. No definite relative afferent pupillary defect was noted and ocular motility was full. He had no enophthalmos or proptosis. An exodeviation measuring 40 prism dioptres was noted. Ophthalmoscopy demonstrated normal retinal perfusion with no pallor or oedema of the optic nerve head. Figure 1: Axial CT scan showing fracture line extending from nasal bones posteriorly across the skull base to the right ear canal. There is blood in the nasal and maxillary sinuses. Figure 2: Axial CT scan showing fracture extending through right sphenoidal sinus and bisecting right carotid canal. Figure 3: Axial CT scan showing extensive frontal lobe contusions. Citation: Bansal S (2013) Traumatic Chiasmal Syndrome A Case Report. Int J Ophthalmic Pathol 2:4. • Page 2 of 3 • doi:http://dx.doi.org/10.4172/2324-8599.1000121 Volume 2 • Issue 4 • 1000121 injury to the chiasm. There were no signs suggestive of chiasmal swelling, compression, haemorrhage or infarction. The patient developed no cranial nerve palsies, neuro-endocrine abnormalities or neurological deficits. 3 months after the injury visual acuity was 6/6 in the right eye and 6/12 in the left. His colour vision was recorded at 16/17 plates for the right eye and 7/17 plates for the left on the Ishihara test. No afferent pupillary defect was noted and there was mild optic nerve pallor in a “bow tie” distribution bilaterally. Although the central scotoma did resolve, he was left with a stable bitemporal hemianopia.