A Cross-Sectional Study of Clinical Spectrum and Outcome of Pure Midbrain Strokes

Pure mesencephalic infarcts are uncommon, the main clinical manifestations being oculomotor signs and ataxia.

Primary objective was to determine the incidence of pure midbrain strokes. We also evaluated the clinical spectrum, syndromes, arterial territories involved, risk factors, and outcome at 3 months.

This cross-sectional study was conducted at the Neurology department of a tertiary teaching hospital in Kerala.

We recorded clinical examination and radiological details of all the patients who presented with isolated midbrain strokes from December 2014 to December 2019. The clinical spectrum and outcomes of the patients at 3 months were analyzed.

Of the 520 posterior circulation stroke patients, 48 (9.2%) had isolated mesencephalic infarcts. Clinical manifestations included gait ataxia in 40 patients (83.3%), third nerve palsy in 29 (60.41%), fourth nerve palsy in 4 (8.3%), internuclear ophtalmoplegia in 9 (18.8%), upgaze paresis in 3 (6.3%), hemiparesis in 4 (8.3%), and cheiro-oral paraesthesia in 4 (8.3%). Of the 48 patients, 21 (43.8%) had Claude syndrome, 9 (18.8%) had Wernekink commisure syndrome, 6 (12.5%) had ataxic hemiparesis, 3 (6.3%) had Parinaud syndrome, 3 (6.3%) had Weber syndrome, 4 (8.3%) had Nothnagel syndrome, and 1 patient had a pure sensory stroke (2.1%). The anteromedial territory was frequently affected, in 37 (77%), characterized by oculomotor manifestations and ataxia. Posterior lesions were noted in three (6.3%), anterolateral lesions in three (6.3%), and lateral lesion in one (2.1%) patient. Combined lesions in posterior and paramedian territory were seen in four (8.3%). At the end of 3 months, 30 patients (62.5%) had a modified Rankin score of one.

Our study provides the incidence of midbrain stroke over 5 years. It also highlights the heterogeneity of clinical features of pure midbrain infarcts.