Ataxic hemiparesis due to midbrain infarction

Kim et al. Neurology 2005;64:1227-1232

40 patients with midbrain infarction were divided into 4 types. 1) Anteromedial/paramedian group with lesions near the red nucleus (n=18) (IIIn palsy, INO, ataxia, perioral/ restricted hand numbness without weakness) 2) anterolateral group involving the crus cerebri and pyramidal tract and the substantia nigra (n=11) Symptoms were hemi-ataxia +/- hemiparesis 3) combined anterior group (n=6) and 4) lateral group involving the medial lemniscus and ascending trigeminal tract (n=2). These patients had sensory disturbance only. 5) 3 had bilateral/atypical lesions.

Symptoms in descending order were: gait ataxia (68%), dysarthria (55%), limb ataxia (50%), sensory symptoms (43%), IIIn palsy (25 %), limb weakness (23 %) and INO (13 %). Two syndromes were pure sensory stroke (group 4) and ataxic hemiparesis (usually thought to be either pontine or capsular).

Etiology were large vessel disease (60%) of BA or VA; small vessel disease in 25 %; cardioembolism in 3 %; unknown in 13 %. Of the large vessel disease patients , 71 % had atheromatous branch artery occlusion, 17 % had artery to artery embolus,and the rest were unknown.