4 vht- compensation
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1. Vestibular habituation therapy (VHT) uses repeated exposure to "mismatched" sensory input through exercises to induce habituation and adaptation, helping patients regain normal balance after peripheral vestibular dysfunction. 2. Exercises in VHT range from basic eye and head movements in bed, to more advanced activities incorporating trunk and whole body movement like throwing and catching balls while walking or playing games. 3. Drugs like betahistine that facilitate vestibular compensation are suitable for use with VHT, unlike sedatives which can delay the process.
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4 vht- compensation
- 2. 2 Vestibular Rehabilitation Adaptation a phenomenon which helps a patient with persisting peripheral dysfunctional state to regain normal balance. Habituation repeated exposure of the body to “mismatched “ sensory input. Compensation a goal directed process induced by some recognized errors, directed towards its elimination Norre M E, Crit. Rev. Phy. Rehab. Med., 1990, 2, 2, 101-120, Kirtane MV, Ind. J. Otolaryngol HNS, 1999, 51 (2), 27-36.
- 3. 3 Vestibular compensation Right labyrinth damaged Left Labyrinth normal Less electrical discharge Normal electrical discharge Imbalance between two sides- Vertigo Sensation of unequal inputs from two sides by CNS Habituation and adaptation to the error possible ways increasing elect. discharge from Decreasing electrical discharge from damaged labyrinth normal labyrinth Not possible Cerebellar Clamp or Vestibular shutdown Biswas A, ‘Neurotological Diseases’ IN An Introduction to neurotology, 1998, 85-7.
- 4. 4 Acute compensation by cerebellar clamp or vestibular shutdown Cerebellum through connections with Vestibular nuclei induces reduction in resting electrical discharge- cerebellum induced vestibular shutdown Reduces inequality between electrical discharge between the two sides by lowering electrical discharge of normal vestibular labyrinth Advantages symptomatic relief of vertigo in acute case At rest, no vertigo Disadvantage reduced vestibular sensitivity Inhibited vestibular system fails to react normally to vestibular assault Sudden head movement leads to vertigo Chronic compensation is essential . Biswas A, Neurotological Diseases IN ‘An Introduction to neurotology”, 1998, 85-7.
- 5. 5 Normal situation Right vestibule equal Left vestibule Right vestibular nuclei Left vestibular nuclei Vertigo Right vestibule damaged Left vestibule normal Less electrical normal electrical. Discharge discharge Right vestibular nuclei left vestibular nuclei Chronic compensation for vertigo Biswas A, Neurotological Diseases IN ‘An Introduction to neurotology”, 1998, 85-7.
- 6. 6 Right vestibule damaged Left vestibule normal normal electrical discharge Right vestibular nuclei Left vestibular nuclei Chronic Compensation Chronic compensation equal synapse equal brain Biswas A, Neurotological Diseases IN ‘An Introduction to neurotology”, 1998, 85-7.
- 7. 7 Chronic compensation Inhibitory effect of cerebellum on vestibular nuclei is gradually removed and requisite anatomical restructuring of central vestibular pathways takes place Cerebellum monitors afferent ( sensory) and efferent (motor) inputs form the two sides Vestibular nuclei on damaged vestibular side gets connected anatomically and functionally to vestibular nuclei on normal vestibular side. Capacity of cerebellum to adapt to the affected or changed vestibular scenario is called plasticity of CNS. Biswas A, Neurotological Diseases IN ‘An Introduction to neurotology”, 1998, 85-7.
- 8. 8 Chronic compensation Whole compensatory mechanism controlled by CNS , mediated by cerebellum. Compensatory mechanism ineffective if cerebellum malfunctioning, (Cerebellar degeneration) If after the above compensatory mechanisms, still errors in vestibular functioning, corrected by other afferent such as propioceptive and visual system. Central compensation initiated and enhanced by head movements- adaptation exercises and vestibular habituation therapy Biswas A, Neurotological Diseases IN ‘An Introduction to neurotology”, 1998, 85-7.
- 9. 9 Do’s and don’ts in encouraging vestibular compensation Encourage Alertness Active & passive movements Large Support Surface Fine motor task Visual stimuli General care Avoid Sedation Immobility Dark environment Solitude standing Kirtane MV, Ind. J. Otolaryngol HNS, 1999, 51 (2), 27-36.
- 10. 10 Antivertigo drugs used with Vestibular habituation Therapy (VHT) Antivertigo drug used should facilitate (or at least not hinder) vestibular compensation. Antivertigo drugs with sedative effect delay vestibular compensation and hence are counteradvised in VHT Kirtane MV, Ind. J. Otolaryngol HNS, 1999, 51 (2), 27-36.
- 11. 11 Antivertigo drugs used with Vestibular Habituation Therapy (VHT) “Antivertigo drugs like Cinnarizine, Flunarizine… sedation is a common adverse effect…delays compensation.” --Kirtane MV, Ind J. Otolaryngol, 1999, 51(2) “Sedatives, ..antihistamines, flunarizine, Cinnarizine..slow down vestibular compensation.” --Norre, Crit. Rev. Phy. Rehab. Med, 1990, 2(2), 101-20
- 12. 12 Antivertigo drugs used with Vestibular Habituation Therapy (VHT) “..Betahistine has been shown to hasten the compensation and hence is suitable for use with VRT “(Vestibular Rehabilitation Therapy)” -Kirtane MV, Ind J Otolaryngol HNS, 1999, 51(2), 27 “..betahistine..regarded as a useful therapy for improving vestibular compensation..” --Tighilet B et al,J.Vest.Res, 1995, 5(1), 63
- 13. 13 Following Vestibular neurectomy (in patients with meniere’s disease) , medical treatment given to facilitate vestibular compensation Betahistine 16 mg t.i.d. Cinnarizine 25 mg t.i.d. n=28 n=34 Colletti, Acta Otolaryngol, 2000, suppl 544, 27-33 Betahistine & Cinnarizine: A comparative study of effect on vestibular compensation
- 14. 14 Results: Assessment of vestibular compensation by Vestibulo- ocular reflex (VOR) asymmetry Lesser the VOR asymmetry, higher the vestibular compensation Colletti, Acta Otolaryngol, 2000, suppl 544, 27-33 VOR asymmetry score Treatment groups Day 15 Day 30 Day 90 Betahistine 15 5 2 Cinnarizine 15 9 7
- 15. 15 Colletti, Acta Otolaryngol, 2000, suppl 544, 27-33 Results: Comparing efficacy of Betahistine and Cinnarizine in facilitating vestibular compensation Lesser VOR asymmetry score with Betahistine treatment than with Cinnarizine treatment Higher degree of vestibular compensation with Betahistine than with Cinnarizine Faster recovery with Betahistine than with Cinnarizine
- 16. 16 -Tighilet B. et al, J.Vest. Res., (1995), 5, 53-66 Betahistine - Effect on Vestibular Compensation in Cats 13 adult cats subjected to left side vestibular nerve lesion Assessment : Posture recovery Locomotor balance recovery Time course of recovery process
- 17. 17 Faster Recovery: Betahistine facilitates vestibular compensation -Tighilet B. et al, J.Vest. Res., (1995), 5, 53-66
- 19. 19 EXERCISES IN BED : EYE MOVEMENTS Looking up and then down
- 20. 20 EXERCISES IN BED : EYE MOVEMENTS Looking alternately left and right
- 21. 21 EXERCISES IN BED : EYE MOVEMENTS Convergence Exercises
- 22. 22 EXERCISES IN BED : HEAD MOVEMENTS Bending alternately forward and backward
- 23. 23 EXERCISES IN BED : HEAD MOVEMENTS Turning alternatively to the left and then right
- 24. 24 Shrugging and rotating shoulders EXERCISES IN SITTING POSITION
- 25. 25 Bending forward and picking up objects from the floor EXERCISES IN SITTING POSITION
- 26. 26 EXERCISES IN SITTING POSITION Turning head and trunk alternately to the left and the right
- 27. 27 Changing from sitting to standing, initially with eyes open and then with the eyes closed EXERCISES IN STANDING POSITION
- 28. 28 Throwing a small (ping pong) ball in, an arc from hand to hand and following it with the eyes EXERCISES IN STANDING POSITION
- 29. 29 EXERCISES IN STANDING POSITION Throwing a small ball from hand to hand under the knee
- 30. 30 Throwing and catching the ball while walking EXERCISES WHILE WALKING
- 31. 31 Walking around in the room with eyes open and closed EXERCISES WHILE WALKING
- 32. 32 Walking up and down a flight of stairs EXERCISES WHILE WALKING
- 33. 33 Playing any game involving bending, stretching and aiming with the ball EXERCISES WHILE WALKING
Editor's Notes
- VRT is gaining wide acceptance and increasing importance in the management of vertigo. It is now widely accepted as an integral part of clinical management of vertigo.
- Adaptation, habituation and compensation are mechanism involved in the VRT process. Adaptation is not the result of one particular system but is the distributed property of many system and CNS. Beside the basic phenomenon at vestibular nuclei, other systems like visual system, spinal cord. Cerebellum, proprioceptive ( musculoskeletal) systems play an important role Habituation is the fundamental mechanism of all adaptive processes. Repeated exposure to vestibular defect (error situation) will induce such changes in CNS that vestibular defect is annihilated for la long time. Repeated exposure to vestibular defective stimulus is the indispensable condition Compensation can take place in two ways vestibular compensation, in which normal labyrinth will send modified responses to adjust for error situation created by defective labyrinth. Non -vestibular compensation in which visual and propioceptive input will substitute for incorrect vestibular input. We will review vestibular compensation in more details in further slides.
- For the maninatanenec of stability it is very essential that electrical discharge from the two sides is equal. If one of the labyrinth is severely damaged, there will be very little or no elctrical dischage from that labyrinth. This wiil,lead to gross inequality between th etwo sides, resulting in vertigo an imbaalance. Over a period of time, after repeated exposure to this situation, Vestibular compensation is brought about by CNS mainly, through Cerebellum. CNS has an inherent capacity to bring about corrective changes when there is weakening of function on any part of peripheral nervous system. The asymmetry between the electrical discharge between the two sides is sensed by CNS and in turn it responds by causing requisite changes. It is possible by two ways. A. by increasing electrical discharge from damaged labyrinth. This is not possible. B. by decreasing the electrical discharge from normal intact labyrinth. This is achieved with the help of cerebellum by process called Cerebellar clamp or vestibular shutdown.
- Cerebellum through its connections with vestibular nuclei, induces reduction in resting electrical discharge of the vestibular nuclei, called a s vestibular shutdown. The advantage of this process is reduction in symptoms of vertigo, nausea etc. The disadvantge fo this process is reduced vestibular sensitivity. Inhibited vestibular system fails to react to vestibular assault. Hence sudden change of head position will cause vertigo, while at rest there will be no vertigo. Once acute symptoms are controlled, chronic compensation takes place. The inhibitory effect of cerebellum on vestibular nuclei is gradually removed. And requisite anatomical changes are initiated at brainstem region so that healthy labyrinth can now serve the total labyrinthine requirement of patient. This restructuring of central vestibular pathways occur so that vestibular nuyclei on the damaged side gets connected anatomically and functionally to vestibular nuclei on the healthy labyrinth side. This restructuring of the synapses at the level of brain stem is functionally very much like developments of vascular collaterals after a blood vessel has been blocked. When the natomical restrucring takes place as discussed ijn earlier slide, when there is vestibular assault e.g. sudden change in head position, Vestibular nuceli on damaged side gets input from vestibular nuclei on intact side and not from affected vestibule.
- In normal situation in healthy person, right vestibular nuclei gets information rogt vestibule and left vestibular nuclei gets input from left vestibule In vertigo episode, right vestibule is damaged, it sends incorrect input to right vestibular nuclei.. Left vestibular nuclei gets input from intact left labyrinth. Then there is a imbalance between the two sides. When the natomical restrucring takes place as discussed ijn earlier slide, when there is vestibular assault e.g. sudden change in head position, Vestibular nuceli on damaged side gets input from vestibular nuclei on intact side and not from affected vestibule. This process of central compensation is initiated and enhanced by activities provoking vertigo and inhibited by inactivity.
- Classical advise still given in vertigo patients is “ Avoidance therapy “. The patient is advised “ not to move” and “to avoid the movements eliciting vertigo”. Most patients manifest this because of fear of vertigo. Rehabilitation is the opposite of avoidance therapy. The basic principle behind compensation is the repeated exposure of the patient to vertigo attacks and hence avoidance therapy will only lead to decompensation. After initial vestibular compensation is complete, symptoms amy appear because of decompesantion. Decompensation si triggered by change in medication, inactivity, fatigue etc. Hnece it is very essential for vestibular compensation that patient should be alert, active etc.
- Many antivertigo drugs typically used such as vestibular suppressants cause sdeationa nd CNS depression. These may be useful in initial stages to control a n acute attack of vertigo. But if used for prolonged periods,may be counterproductive for vestibular compensation. Some of the drugs induce decompensation in an already compensated individual. Sedative effect ahs to be avoided when compensation and habituation need to be developed. Antihistamines, Cinnarizine, Flunarizine, produce sedation. Hence if used for long period, may delay or hinder compensation. Hence should not be used along with vestibular Rehabilitation therapy.
- Method : 13 adult cats were subjected to left side nerve lesion. Post-operatively they were divided in 3 groups -Gr I-Betahistine 50mg/kg/d, Gr II - Betahistine 100mg/kg/d, Gr III - control. Assessment : Posture recovery was assessed by measuring support surface of the cats while standing erect on four legs. Practically it was measured as the surface delimited by the four legs on the ground using chalk as a marker. Locomotor balance recovery was determined using rotating beam test. The recovery profile & time course of these static (posture) & dynamic (equilibrium) functions in three groups of cats were compared
- Tighilet in a study of vestibular compensation in cats, reported that oral Betahistine (50 or 100 mg /kg bodywieght) significantly accelerated recovery in posture and balance following transection of left side vestibular nerve. Treated cats exhibited near normal values 20-25 days after vestibular lesion, compared with 35-40 days in acontrol group which did not receive Betahistine. Thus Betahistine facilitates vestibular compensation in cats.
- Adaptation exercies were first reported by Cawthorne and Cooksey ( Cooksey, 1945). Cawthorne discovered that acreful explanation of the phusiology of the situation, coupled with graduated series of exercises designed to encourage head and eye movements was the optimum method of hastening recovery. The exercises by Cawthorne and Cooksey have over the years proved their worth in a range of vestibular disorders. These exercises are named as “Cawthrone and Cooksey exercises”. There have been modifications sugegsted by many researchers in the same over the years. VRT comprises of a series of exercises or maeuvers designed to stimulate the vestibular system. These movements which in initial stages provoke vertigo, are combined with exercises involving eye movements and postural changes which encourage vestibular compensation.