(13.02) A case of meningioma with oculomotor nerve palsy in a patient with acromegaly responded to oral octreotide

Meningiomas are the most common primary central nervous system (CNS) tumors. The current recommended measures to treat large or symptomatic meningiomas are surgical resection (if feasible) and radiotherapy. In this case, a patient with acromegaly was diagnosed with meningioma manifested with a mass effect on the oculomotor nerve. Mass size was significantly reduced with the resolution of 3^rd nerve palsy following increasing the dose of oral octreotide.

Case(s) Description :

A 65-year-old female with a history of acromegaly had transsphenoidal hypophysectomy followed by radiotherapy (received a total dose of 4500 GY) and started on monthly octreotide injections, then switched to oral octreotide 20 mg BID (40 mg daily). IGF1 was maintained within the normal range. Twenty years later, after the initial surgery and radiation therapy, she presented to the emergency department with a sudden onset of blurring of vision and was found to have severe left 3rd nerve palsy. Brain MRI showed an 11x9x9 mm enhancing mass within the left cavernous sinus, displacing the left oculomotor nerve and abutting the internal carotid artery. Neurosurgery and radiation oncology were consulted. However, treatment with the intervention was not feasible due to the location of the mass.

Given that recurrence of acromegaly was considered in the differential diagnosis (IGF1 was at the upper normal range at that time), the dose of oral octreotide was increased from 20 mg BID to 40 mg BID (80 mg daily). Shortly after increasing the dose of oral octreotide, the left 3rd nerve palsy started to improve clinically until it ultimately resolved in 2 months. Repeated MRI after 2 months of increasing octreotide dose showed a significant (75%) tumor volume reduction.

Discussion :

Although we did not have a confirmed tissue diagnosis, given the history of radiation therapy and the imaging features (homogeneous enhancement and the appearance of the mass), most likely this mass is a meningioma. Somatostatin receptors (SSTRs) expression in meningiomas was previously reported. All SSTRs, especially SSTR2 are expressed in the meningiomas. There are reported cases of meningioma that responded to treatment with octreotide in the literature. In this case, the size of the meningioma reduced relatively fast, and the mass effect that led to 3^rd nerve palsy resolved in response to increasing the dose of oral octreotide. Despite this being an off-label use of this medication, oral octreotide could be a reasonable choice of treatment when the meningioma occurs in a challenging location, such as in our case, for which neither surgical nor radiation treatment is the best option.