Behavioural improvement in a minimally conscious state after caloric vestibular stimulation: evidence from two single case studies.
OBJECTIVE
To investigate whether caloric vestibular stimulation, a non-invasive form of neuro-modulation, alters the level of awareness in people residing in a minimally conscious state.


METHODS
Single-case ( n = 2), prospective, controlled (ABAB) efficacy study.


METHODS
Tertiary, neuro-rehabilitation inpatient ward within a university hospital.


METHODS
Two individuals in a minimally conscious state.


METHODS
Left ear caloric vestibular stimulation was performed in two four/five-week blocks interleaved with two four/five-week blocks of sham stimulation. Session duration and frequency gradually increased within each block from once per day for 10 minutes (Week 1) to once per day for 20 minutes (Week 2) to 20 minutes twice per day in the remaining weeks.


METHODS
Wessex Head Injury Matrix, JFK Coma Recovery Scale - Revised.


RESULTS
Both participants' Wessex Head Injury Matrix scores indicated a transition from involuntary (i.e. mechanical vocalization) to voluntary (i.e. gesture making, selective responses to family members) behaviour that was time-locked to the onset of active stimulation. In one participant, this improvement persisted for at least four weeks after active stimulation, while in the other it diminished two weeks after stimulation. Allied, although less dramatic, changes were seen on the arousal and auditory subscales of the JFK Coma Recovery Scale - Revised.


CONCLUSIONS
The data provide the first evidence that vestibular stimulation may help improve outcome in a low awareness state, although further studies are needed to replicate effect and determine longer-term benefit.
1 School of Psychology, University of Kent, Canterbury, UK.
Serena
S
Vanzan
1 School of Psychology, University of Kent, Canterbury, UK.
David
D
Wilkinson
1 School of Psychology, University of Kent, Canterbury, UK.
Heather
H
Ferguson
2 KentHealth, University of Kent, Canterbury, UK.|3 Department of Neurology, East Kent Hospitals University NHS Foundation Trust, Kent, UK.
Patrick
P
Pullicino
4 East Kent Neuro-Rehabilitation Service, East Kent Hospitals University NHS Foundation Trust, Kent, UK.
Mohamed
M
Sakel
D000368:Aged; D002150:Caloric Tests / Q000295:instrumentation / Q000379:methods*; D002544:Cerebral Infarction / Q000150:complications* / Q000209:etiology; D018592:Cross-Over Studies; D015600:Glasgow Coma Scale; D006323:Heart Arrest / Q000150:complications* / Q000209:etiology; D006801:Humans; D008297:Male; D008579:Meningioma / Q000601:surgery*; D008875:Middle Aged; D018458:Persistent Vegetative State / Q000209:etiology / Q000534:rehabilitation*; D011183:Postoperative Complications; D013788:Thalamus / Q000473:pathology / Q000601:surgery*; D016896:Treatment Outcome; D014693:Ventricular Fibrillation / Q000150:complications
Caloric stimulation; disorders of consciousness; minimally conscious state