Isolated brainstem cysticercosis: A review

Abstract

Objective

Review of patients with isolated brainstem cysticercus to outline the features of this form of neurocysticercosis.

Methods

MEDLINE and manual search of patients with isolated brainstem cysticercus. Abstracted data included: demographic profile, clinical manifestations, neuroimaging findings, evolutive stage of parasites neurocysticercosis, therapy, and follow-up.

Results

Twenty-nine patients were reviewed. Of these, 22 (76%) came from India. Mean age was 31 years, and 72% were men. Parasites were located in midbrain (16 patients), pons (12 patients), and medulla (one patient). All but three lesions were less than 10 mm in diameter and most were at or near the midline. Most common clinical forms of presentation were isolated paresis of the third cranial nerve, internuclear ophthalmoplegia, and crossed brainstem syndromes. Neuroimaging studies showed colloidal cysticercus in 24 patients, vesicular cysts in four, and a calcification in one. Fourteen patients received cysticidal drugs, eight were treated with steroids alone, and three received no therapy at all. The remaining four patients underwent surgical resection of the lesion. Twenty-seven patients recovered completely and the remaining two were left with mild sequelae. Control neuroimaging studies showed complete or partial resolution of the lesion in the 18 patients in whom they were performed.

Conclusions

Isolated brainstem cysticercosis is rare. Clinical and neuroimaging findings on admission allowed a correct differentiation of this condition from other space-occupying lesions of the brainstem (tuberculomas, abscesses, gliomas) in most patients. The prognosis is benign provided the patients receive prompt therapy.

Introduction

Neurocysticercosis is highly pleomorphic due to individual differences in the number and location of lesions within the CNS [1]. Cysticerci may be located in brain parenchyma, subarachnoid space, ventricular system, or spinal cord. In the former, parasites usually lodge in the cerebral cortex or the subcortical white matter, due to the high vascular supply of these areas [2]. So, parenchymal brain cysticercosis usually presents as recurrent seizures which, in up to 70% of cases, constitutes the sole manifestation of the disease [3], [4], [5]. Brainstem location of parenchymal cysticerci usually happens in the context of disseminated disease with simultaneous involvement of cerebral hemispheres, basal ganglia, or cerebellum [6], [7]. The occurrence of isolated brainstem cysticercosis poses diagnostic and therapeutic challenges as this form neurocysticercosis seems to be rare, may present with clinical and neuroimaging findings indistinguishable from those of other brainstem lesions, and creates concern on the potential risks related to therapy. Here, the literature on isolated brainstem cysticercosis is reviewed to outline its clinical features, and to comment on the diagnostic and therapeutic challenges of this overlooked form of the disease.