Lip and tongue function differently affected in individuals with multiple sclerosis.

Clinical dysarthria test scores on lip function and tongue function were compared for 77 dysarthric as well as non-dysarthric subjects with multiple sclerosis (MS) and 15 control subjects. Results show that tongue function was significantly more severely affected than lip function in individuals with MS. Furthermore, tongue function, but not lip function, was significantly more severely affected in the MS individuals with no dysarthria compared to the control group. Test items requiring increased rate of movement (oral and verbal diadochokinesis) were significantly more severely affected than the items requiring range and force of movement, but only in the dysarthric MS subgroup. Moderate correlations were found between tongue and lip function and neurological deficit scores, number of years in disease progression, and perceptually perceived consonant and vowel precision. Consequently, tongue dysfunction can be detected clinically and subclinically using a dysarthria test procedure, and as an early sign of articulatory dysfunction it should be an early target in therapeutic interventions.