Tongue Deviation in Acute Ischaemic Stroke: A Study of Supranuclear Twelfth Cranial Nerve Palsy in 300 Stroke Patients

Abstract

It is generally believed that the supranuclear innervation of the hypoglossal nucleus is bilateral and symmetrical. The aim of this work is to study the frequency and clinical characteristics of supranuclear tongue palsy in unilateral stroke. 300 patients with acute unilateral ischaemic motor strokes (excluding those in the lower brainstem) and an equal number of normal controls were studied for the presence of tongue deviation in a standardised manner. 29% of stroke patients and 5% of controls had tongue deviation (p < 0.00001). Deviation was always to the side of the limb weakness. In patients with a history of stroke, it occurred more frequently in those with previous stroke on the contralateral side. Tongue deviation was most common in patients with clinical features of the non-lacunar stroke subtype (56%) or in those with cortical or large subcortical infarctions on brain CT scan (55 and 45%, respectively). All tongue deviations were associated with supranuclear 7th nerve palsy. Dysphagia and dysarthria occurred in 43 and 90% of patients with tongue deviation. Weakness of the arm was significantly associated with presence of tongue deviation. Tongue deviation in unilateral stroke most likely results from asymmetrical supranuclear control of the 12th cranial nerve in many individuals. The finding that it occurs relatively commonly in large (non-lacunar) infarcts and its association with dysphagia may have clinical utility.