Tension arachnoid cyst with transtentorial herniation: A rare entity

Arachnoid cyst presenting as a neurosurgical emergency: a case report

Introduction

Arachnoid cysts are intra-arachnoid lesions filled with cerebrospinal fluid. They account for ~1% of all intracranial mass lesions and are non-neoplastic collections of cerebrospinal fluid within an anomalous arachnoid enclosure.

Case presentation

The authors report a 35-year-old Arabian male who presented to the ER with a history of sudden loss of consciousness, anisocoria, and right hemiparesis. Contrast tomography showed a large frontoparietotemporal cyst (7.7×5.8×5.4) with uncal herniation and a midline shift of 12 mm. An emergency left FTP craniotomy with an excision of the cyst was performed.

Discussion

Arachnoid cysts can be categorized as primary or secondary, arising congenitally or due to factors like trauma, infection, or neoplasia. It can rupture, leading to internal bleeding, causing symptoms such as headaches, seizures, and neurological decline. Rapid diagnosis is vital, with cranial computed tomography scans preferred for emergencies. Treatment options include surgical intervention like craniotomy, fenestration, or cyst peritoneal shunts. For uncal herniation, surgery can be successful and results depends on the amount of herniation.

Conclusion

Although benign, the arachnoid cysts led to uncal herniation when they become 'tension' cysts. A high level of suspicion is crucial for early recognition of the condition. Timely intervention has shown positive recovery outcomes.

Short Report on a Rare Presentation of Temporal Arachnoid Cyst and Lessons Learned

BACKGROUND

Stiff neck or nuchal rigidity is a significant clinical sign of neurologic disease. It is commonly associated with meningitis, subarachnoid hemorrhage, and posterior fossa tumors. It may also occur as a result of tonsillar impaction following pressure in the infratentorial compartment from an expanding posterior fossa mass. It is, however, not commonly known to be associated with uncal herniation.

CASE DESCRIPTION

We report a recent experience on this association.

CONCLUSIONS

In the presence of stiff neck or nuchal rigidity in a patient with clinical signs of uncal herniation from a temporal arachnoid cyst, this unusual association could possibly be owing to the effect of increased pressure in the posterior fossa from massive shift of brain tissue posteriorly following a rapid rise in middle cranial fossa pressure consequent on an acute enlargement of the cyst. A false impression of acute meningeal irritation in such a situation could be quite misleading, resulting in late diagnosis and subsequently a delay in timely intervention.