Prevalence of Muscle Hypertonia on Admission and Discharge from Inpatient Rehabilitation After Traumatic Brain Injury

Research Objectives: To determine the prevalence of muscle hypertonia in the upper extremities (UE) on initial inpatient rehabilitation admission after traumatic brain injury (TBI) and subsequent evolution of hypertonia from admission to discharge.

Design: Retrospective longitudinal cohort study.

Setting: Tertiary care inpatient rehabilitation center participating in NIDILIRR TBI Model Systems Program.

Participants: Consecutive sample of individuals admitted for initial inpatient rehabilitation for TBI (n=308).

Interventions: None

Main Outcome Measures: Ashworth scores (AS, 0-4) were collected by therapists on admission and discharge in 15 upper extremity muscles, bilaterally. Hypertonia was considered present if AS was at least 1 in any muscle.

Results: On admission (25 days post-TBI on average ), hypertonia was present in at least one of 15 upper extremity muscles in 37 out of 308 individuals (overall prevalence rate, 12%). Unilateral hypertonia was found in 24 individuals (8%) and bilateral hypertonia in 13 individuals (4%). On discharge (length of stay, 23 days on average), hypertonia was present in at least one of 15 upper extremity muscles in 26 out of 308 individuals (overall prevalence rate, 8%). Unilateral hypertonia was found in 16 individuals (5%) and bilateral hypertonia in 10 individuals (3%). The decrease in prevalence from admission to discharge was significant (McNemar-Bowker test p = 0.011). Regarding distribution across different muscles, hypertonia on admission was most prevalent in the elbow flexors (13%), wrist flexors (11%), shoulder internal rotators (10%), shoulder adductors (9%), and finger flexors (8%). By the time of discharge, the prevalence of hypertonia decreased to 10% in elbow flexors (McNemar test p = 0.007), 7% in wrist flexors (p < 0.001), 7% in shoulder internal rotators (p = 0.007), 6% in shoulder adductors (p = 0.001), and 6% in finger flexors (p = 0.029).

Conclusions: Muscle hypertonia was uncommon in this cohort of initial rehabilitation admissions with TBI. Prevalence decreases over the inpatient stay. Spontaneous recovery, therapeutic procedures, and medications prescribed may account for these results, which warrants further investigation.

Author(s) Disclosures: Brycen L. Scott - No conflicts to disclose
Clayton A. Moss III, MD - No conflicts to disclose
Stuart A. Yablon, MD - No conflicts to disclose
Dobrivoje S. Stokic, MD, DSc - No conflicts to disclose