Subtle Dysmetria After a Hemorrhage in the Basal Ganglia and Lentiform Nucleus

A 62-yr-old woman with a history of hypertension and diabetes presented to an outside hospital with right side weakness. Computed tomography showed a hemorrhage in the left basal ganglia and lentiform nucleus. On admission to acute inpatient rehabilitation a week later, strength was 5/5 on the left side and 3/5 on the right. On the finger-to-nose test on the right, she lost a smooth trajectory approximately 75% of the way through the reaching process and then had small amplitude vertical oscillations before reaching the target. She ambulated 100′ using a rolling walker with minimum assistance to recover occasional loss of balance especially during turns and demonstrated inconsistent right foot placement and clearance. When discharged 12 days later, strength was 4/5 on the right, dysmetria was improved but retaining the same characteristics (Video 1), and she ambulated 300′ and negotiated 2+ turns with a rolling walker.

Ataxia and dysmetria associated with midbrain lesions have been recognized for over a century. Seven of 13 patients with a stroke in the lentiform nucleus were found to have ataxia.¹ We have not seen the dysmetria secondary to a stroke in the lentiform nucleus characterized or illustrated. The rehabilitation courses of patients with noncerebellar ataxia-dysmetria syndromes have recently been discussed, and it has also been appreciated that the dysmetria in these syndromes is different than that caused by a cerebellar lesion and indeed distinct to each lesion site: in patients with a thalamic lesion,² dysmetria does not start until the last ~25% of end range reaching and there is no hemiparesis. Pontine lesions usually present with some degree of hemiparesis, which usually improves quickly, and dysmetria³ starting the first 30% of the reaching process. Lesions in the corona radiata cause hemiparesis and dysmetria³ that starts about halfway into the reaching process. We suggest that a stroke in the lentiform nucleus can cause a contralateral ataxia-dysmetria syndrome, presumably due to a lesion of pontocerebellar fibers, with the dysmetria being most similar in character, but with a smaller amplitude of oscillations, to that seen in patients with thalamic strokes (Video 1).²

This study conforms to all CARE guidelines and reports the required information accordingly (see Supplemental CARE Checklist file, Supplemental Digital Content 1, https://links.lww.com/PHM/A820). The patient gave written consent for use of the video.