Diplopia and visual impairment as presenting symptoms of shunt failure in association with tonsillar herniation in idiopathic intracranial hypertension

Cranial nerve palsy secondary to cerebrospinal fluid diversion

OBJECTIVE

Cranial nerve palsy (CNP) secondary to cerebrospinal fluid (CSF) diversion is less familiar to us as a result of its rarity in incidence and insidiousness in presentation. This study aims to further expound the pathophysiological mechanism, clinical presentation, diagnosis, management and prognosis of CNP.

METHODS

From June 2012 to February 2015, 5 of 347 consecutive patients with CNPs secondary to different CSF diversion procedures were treated at our institution. A systematic PubMed search of published studies written in English for patients developing CNPs after CSF diversion procedures from January 1950 to June 2015 was conducted.

RESULTS

Overall, 29 studies and 5 patients of the current series totaling 53 CNPs met the inclusion criteria. CN II, III, IV, V, VI, VII and VIII were got involved in 2 (3.8%), 2 (3.8%), 5 (9.4%), 1 (1.9%), 44 (83.0%), 4 (7.5%) and 1 (1.9%) patients respectively. Thirty-eight patients (71.7%) developed CNPs following inadvertent lumbar puncture, 8 (15.1%) following lumbar drainage, and 7 (13.2%) following ventriculoperitoneal shunt. Forty-eight (90.6%) patients got resolved completely.

CONCLUSIONS

The proposed mechanism of CNP after CSF diversion procedure is CSF hypovolemia and subsequent downward displacement of the brain and traction and distortion of the vascular and peripheral neural structures. As a result of its distinct anatomic characteristics rather than long intracranial course, CN VI is most commonly affected. With early recognition and timely conservative management, most patients could get favorable recovery.

Management of Cerebellar Tonsillar Herniation following Lumbar Puncture in Idiopathic Intracranial Hypertension

Lumbar puncture is performed routinely for diagnostic and therapeutic purposes in idiopathic intracranial hypertension, despite lumbar puncture being classically contraindicated in the setting of raised intracranial pressure. We report the case of a 30-year-old female with known idiopathic intracranial hypertension who had cerebellar tonsillar herniation following therapeutic lumbar puncture. Management followed guidelines regarding treatment of traumatic intracranial hypertension, including rescue decompressive craniectomy. We hypothesize that the changes in brain compliance that are thought to occur in the setting of idiopathic intracranial hypertension are protective against further neuronal injury due to axonal stretch following decompressive craniectomy.