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Original Investigation
October 2017

Characterization of Head-Trunk Coordination Deficits After Unilateral Vestibular Hypofunction Using Wearable Sensors

Author Affiliations
  • 1Department of Physical Therapy and Athletic Training, University of Utah, Salt Lake City
  • 2Faculty of Health Sciences, The University of Sydney, Sydney, Australia
  • 3Otolaryngology Division, School of Medicine, University of Utah, Salt Lake City
  • 4Doctoral Program in Physical Therapy, US Army–Baylor University, Ft Sam Houston, Texas
JAMA Otolaryngol Head Neck Surg. 2017;143(10):1008-1014. doi:10.1001/jamaoto.2017.1443
Key Points

Question  What is the extent of head movement and head-trunk coordination deficits in individuals 4 to 8 weeks after surgical resection of a vestibular schwannoma?

Findings  In this cross-sectional study, 14 individuals with vestibular hypofunction demonstrated significantly reduced head turn amplitude, reduced head turn velocities, and increased head-trunk coupling during gait tasks requiring angular head movements compared with 20 neurologically healthy individuals.

Meaning  At 4 to 8 weeks after vestibular schwannoma resection, patients demonstrated incomplete recovery of gait, dynamic stability, head movement, and head-trunk coordination, suggesting that early referral for vestibular rehabilitation for these individuals may be beneficial.


Importance  Individuals with vestibular hypofunction acutely restrict head motion to reduce symptoms of dizziness and nausea. This restriction results in abnormal decoupling of head motion from trunk motion, but the character, magnitude, and persistence of these deficits are unclear.

Objective  To use wearable inertial sensors to quantify the extent of head and trunk kinematic abnormalities in the subacute stage after resection of vestibular schwannoma (VS) and the particular areas of deficit in head-trunk motion.

Design, Setting, and Participants  This cross-sectional observational study included a convenience sample of 20 healthy adults without vestibular impairment and a referred sample of 14 adults 4 to 8 weeks after resection of a unilateral VS at a university and a university hospital outpatient clinic. Data were collected from November 12, 2015, through November 17, 2016.

Exposures  Functional gait activities requiring angular head movements, including items from the Functional Gait Assessment (FGA; range, 1-30, with higher scores indicating better performance), the Timed Up & Go test (TUG; measured in seconds), and a 2-minute walk test (2MWT; measured in meters).

Main Outcomes and Measures  Primary outcomes included peak head rotation amplitude (in degrees), peak head rotation velocity (in degrees per second), and percentage of head-trunk coupling. Secondary outcomes were activity and participation measures including gait speed, FGA score, TUG time, 2MWT distance, and the Dizziness Handicap Inventory score (range, 0-100, with higher scores indicating worse performance).

Results  A total of 34 participants (14 men and 20 women; mean [SD] age, 39.3 [13.6] years) were included. Compared with the 20 healthy participants, the 14 individuals with vestibular hypofunction demonstrated mean (SD) reduced head turn amplitude (84.1° [15.5°] vs 113.2° [24.4°] for FGA-3), reduced head turn velocities (195.0°/s [75.9°/s] vs 358.9°/s [112.5°/s] for FGA-3), and increased head-trunk coupling (15.1% [6.5%] vs 5.9% [5.8%] for FGA-3) during gait tasks requiring angular head movements. Secondary outcomes were also worse in individuals after VS resection compared with healthy individuals, including gait speed (1.09 [0.27] m/s vs 1.47 [0.22] m/s), FGA score (20.5 [3.6] vs 30.0 [0.2]), TUG time (10.9 [1.7] s vs 7.1 [0.8] s), 2MWT (164.8 [37.6] m vs 222.6 [26.8] m), and Dizziness Handicap Inventory score (35.4 [20.7] vs 0.1 [0.4]).

Conclusions and Relevance  With use of wearable sensors, deficits in head-trunk kinematics were characterized along with a spectrum of disability in individuals in the subacute stage after VS surgery compared with healthy individuals. Future research is needed to fully understand how patterns of exposure to head-on-trunk movements influence the trajectory of recovery of head-trunk coordination during community mobility.