Glioneuronal brainstem tumor – It's all in the eyes

A previously well man presented with several months’ history of neurological symptoms including diplopia and balance difficulties. Examination revealed fluctuating neurological deficits, fatigable weakness and slowed saccades. Extensive testing revealed mildly elevated cerebrospinal fluid protein, strongly positive single fiber electromyography and a dorsal pontine lesion at the floor of the 4th ventricle. An autoimmune process was felt to best account for the myasthenic presentation while the differential diagnoses for the brainstem lesion included glioma. Aggressive immunotherapy failed to halt clinical deterioration; over months he developed generalized weakness, aspiration pneumonia and died. Post-mortem analysis revealed glioneuronal tumor infiltration throughout the brainstem, cerebellum and along the meningeal surface. This is an unusual case of an infiltrative brainstem lesion, with the presentation suggesting a primary diagnosis of myasthenia gravis. The progressive nature of the illness, despite aggressive immune therapy, together with slow saccades, underscored a more sinister process. Cerebral imaging should be performed in patients with fluctuating neurological symptoms, progressive deterioration, and ocular, bulbar, respiratory, or pyramidal pattern deficits, and differentials for contrast-enhancing brain lesions should include primary brain tumors. In such cases, biopsy must proceed if the disease is of relatively recent onset, to facilitate diagnosis and maximize treatment opportunities.