Primary Extradural Meningioma of Posterior Fossa Associated with Acquired Chiari Malformation: A Short Review

Generally, meningioma is considered intracranial lesion occurring in the intradural compartment. However, meningioma can also occur and usually confined in the extradural compartment called as primary extradural meningioma (PEM). PEM represents a special subgroup of meningioma constitute about 1% of all meningioma. PEM arises outside the subdural compartment and usually contains neither connection underlying subdural structures nor extends into with subdural compartment. It is commonly located in the paranasal sinus, middle ear, rarely in the intradiploic spaces of calvarial bone such as temporal, frontal, and parietal bone and orbit but extremely uncommonly in the occipital and sphenoid bones. Authors did detailed Pubmed search for posterior fossa, occipital bone extradural, ectopic intraosseous meningioma which yielded only four publications in the form of isolated case report analyzing only five case of PEM. Authors report a rare case extradural meningioma in a 40-year-old male, who presented with progressive headache and gait imbalance. Magnetic resonance imaging study of brain revealed the presence of PEM of posterior fossa associated with acquired Chiari malformation. The patient was managed successfully surgically with excision of meningioma and release of associated acquired tonsiallar descent was carried out. Authors are analyzing total of five cases including four cases from published literature and one our current case. PEM of the posterior fossa tends to have equal predilection in male and female (3:3), with a mean age of 48 years (range 25–64 years). All cases were surgically and underwent gross total surgical excision. The clinical features, imagings, and management of this rare entity along with the pertinent literature are briefly discussed.