This document provides information about coma stimulation techniques used to help patients recover from comas. It discusses what defines a coma, different theories behind why coma stimulation may work, principles of coma stimulation, criteria for eligible patients, types of sensory stimulation techniques including auditory, visual, olfactory, oral, tactile, gustatory, kinesthetic, and right median nerve stimulation, parameters for sessions, and a coma stimulation kit. The goal of coma stimulation is to activate dormant or spare areas of the brain and encourage neuronal rewiring through various sensory inputs for unconscious patients.

1. COMA STIMULATION

2. WHAT IS COMA
• Patient’s eyes do not open either spontaneously or to external stimuli
• Does not follow command
• Does not mouth or speak recognizable words
• Does not demonstrate intentional movement ( may show reflexive
movement such as posturing, withdrawal from pain or involuntary
smiling)
• Patient cannot sustain visual pursuits through a 45° arc in any
direction when the eyes are held open manually.
(American Congress of Rehabilitation Medicine, 1995)
Coma is a profound state of unconsciousness.

3. COMA STIMULATION
• Coma stimulation programme is an approach based on stimulating the
unconscious person’s senses of hearing, touch, smell, taste and vision
individually in order to help their recovery.
• Types: Unimodal/Multimodal
• Techniques:
Visual/Auditory/Olfactory/Gustatory/Cutaneous/Kinesthetic.

4. THEORIES OF COMA STIMULATION
• Spare capacity and reorganization: Activation of Non-
Active/Spare/Dormant areas
• The redundancy theory: Ability to duplicate neuronal pathways
• The response at a cellular level theory: Collateral sprouting to attempt
rewiring the system.
• The environmental effects theory

5. PRINCIPLES
• Cardinal Rule - Do not harm the
patient
• Check the resting vitals
• Stop immediately in case of
ICP/CPP raise
• Control environmental
distractions
• Organise the stimuli
• Provide distinct and well
differentiated stimuli
• Allow extra time for the patient
to respond
• Meaningful stimuli
• Verbally reinforce responses
• Try stimulating all the senses
• Identify stimuli which the patient
responds to
• Include family participation
Garret, Muehhng, Morrow and Riggs (1990)

6. CRITERIA FOR ELIGIBLE PATIENTS
• Patients with acute hemorrhage, diffuse axonal injury, hypoxia or
stroke
• GCS score less than 10
• RLA score of I, II, III
• Stable vitals
• ICP of less than 15 mm hg for atleast a 24 hour period

7. COMA STIMULATION KIT

8. AUDITORY STIMULATION
• Loud noises e.g., banging two saucepans, ringing bell or rattle,
blowing whistle, clapping hands, reading books, playing tape, TV,
Radio
• Should to irregular to prevent habituation
• Talk to patient, call by patient’s name
• Speak slowly, no complex commands
• Regular stimulation

9. VISUAL STIMULATION
• Flashing Lights, Strobes, Flash cards (Words or pictures printed on
contrast background), photographs, TV
• Reinforce with verbal instruction

10. OLFACTORY STIMULATION
• Use after shave, cologne, perfume, shampoo, eucalyptus oil, patient
favorite coffee or tea
• Avoid vinegar and ammonia
• Provide the stimuli for no more than 10 seconds
• Use garlic and mustard as noxious stimuli

11. ORAL STIMULATION
• Use a sponge tipped or glycerin swab or a soft tooth brush to reduce
hypersensitivity and abnormal oral/facial reflexes.
• Provide stimulation to the lips and area around the mouth.
• Pursing lips, closing mouth or pulling away from the stimulus are the
indicators of right stimulation.

12. TACTILE STIMULATION
• May be facilitatory or inhibitory. E.g., Pain and light touch to skin
produces inhibitory response/ Touch, pressure, slow stroking of the
spine produces facilitatory response
• Avoid unpleasant stimuli like pin prick, Avoid ice to face or body as it
may trigger sympathetic nervous system
• Use variety of textures/ variet of temperatures (warm or cold clothes/
metal spoons dipped for 30 secs in hot or cold water)
• Varying pressure on muscle belly and tendon, rubbing sternum,
pressing nail bed etc.,

13. GUSTATORY STIMULATION
• Provide taste stimulation, unless patient is prone to aspiration.
• Cotton swab dipped in sweet, salty or sour solution
• Avoid excess sweet as it induces more salivation.
• Facial grimacing is an indicator that the taste sensation is working

14. KINESTHETIC/PROPICEPTIVE/
VESTIBULAR STIMULATION
• Slow change in position tend to inhibit/ Faster movements facilitate
arousal
• Mobility activities promote body and positional awareness
• Using Tilt table, Rocking chairs, frequent position changes in bed
• Avoid spinning movements may trigger seizures
• Avoid mechanical inputs like sudden raising and lowering of bed

15. SESSIONS
• Frequency: Start at an hour per day to increase gradually to an intense
6 – 8 hours per day.
• 10 to 15 minute sessions to 45 to 90 minutes sessions as patient
improves.
• Wait for 1 to 2 minutes for response to occur
• Adequate rest in between sessions is recommended

16. RIGHT MEDIAN NERVE STIMULATION
[RMNS]
• Large cortical representation
• Peripheral port
• Spinoreticular component of median nerve
pathway
• RAS & Limbic system
• Activates projections between thalamus
and cortex
• Possibly silent or injured synapses are
transformed into functional ones by
neurotrophic factors
• Increased cerebral blood flow and
enhancement of neurotransmitter
metabolism
Lei J, et al. J Neurotrauma 2015;32:1584–89

17. RMNS - PARAMETERS
• High Frequency biphasic Electrical Stimulation
• Asymmetric biphasic pluses at an amplitude of 15–20 mA (as
tolerated)
• Pulse width of 300 μs at 40 Hz ON for 20 s and OFF for 40 s
• 8 hours per day
Wu X, Zhang C et al., Right median nerve electrical stimulation for acute traumatic coma (the Asia
Coma Electrical Stimulation trial): study protocol for a randomised controlled trial. Trials.
2017;18(1):311.

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