_examination前庭功能检查课件

Vestibular ExaminationVestibular Examination ANATOMY l R l posterior R R discrimination between self movement of body; discrimination between self movement vs. that of the environmentvs. that of the environment Vestibular CortexVestibular Cortex Junction of parietal and insular lobeJunction of parietal and insular lobe Target for afferents along with the cerebellumTarget for afferents along with the cerebellum Both process vestibular information with Both process vestibular information with somatosensory and visual inputsomatosensory and visual input Netter 1997Netter 1997 Tonic Firing RateTonic Firing Rate Vestibular nerve and vestibular nuclei have a Vestibular nerve and vestibular nuclei have a normal resting firing rate normal resting firing rate (70-100 cycles/sec)(70-100 cycles/sec) Baseline firing rate present without head Baseline firing rate present without head movementmovement Tonic firing is equal in both sides; if not, a Tonic firing is equal in both sides; if not, a sense of motion is felt e.g., vertigo, tilt, sense of motion is felt e.g., vertigo, tilt, impulsion, spinningimpulsion, spinning Excitation and inhibition of the vestibular Excitation and inhibition of the vestibular system can then occur from stimulation of the system can then occur from stimulation of the hair cellshair cells Spontaneous recovery with lightSpontaneous recovery with light Vestibular-Ocular Reflex Vestibular-Ocular Reflex (VOR)(VOR) Causes eyes to move in the opposite Causes eyes to move in the opposite direction to head movementdirection to head movement Speed of the eye movement equals that of Speed of the eye movement equals that of the head movementthe head movement Allows objects to remain in focus during Allows objects to remain in focus during head movementshead movements Compensatory Eye MovementsCompensatory Eye Movements VORVOR Optokinetic reflexOptokinetic reflex Smooth pursuit reflex, saccades, vergenceSmooth pursuit reflex, saccades, vergence Neck reflexesNeck reflexes combine to stabilize object on the same area of combine to stabilize object on the same area of the retina=visual stabilitythe retina=visual stability Purves 2001. Vestibular ProcessingVestibular Processing GainGain Keeps eye still in space while head is Keeps eye still in space while head is movingmoving Ratio of eye movement to head movement Ratio of eye movement to head movement (equals 1)(equals 1) Vestibular ProcessingVestibular Processing Velocity Storage MechanismVelocity Storage Mechanism Perseveration of neural firing in the vestibular Perseveration of neural firing in the vestibular nerve by the brainstem after stimulation of SSC nerve by the brainstem after stimulation of SSC to increase time constant to increase time constant (10sec.)(10sec.) SSC respond by producing an exponentially SSC respond by producing an exponentially decaying change in neural firing to sustained decaying change in neural firing to sustained head movementhead movement Otolith does Tone automatically recovers in a few days; does not need visual inputnot need visual input Compensation for reduced gain depends on visual Compensation for reduced gain depends on visual images; takes month to years to complete; high images; takes month to years to complete; high speeds movement-induced symptoms can be lesion; movement-induced symptoms can be chronicchronic Dizzy Patient Presentation: unexplained or Dizzy Patient Presentation: unexplained or new onset of symptomsnew onset of symptoms Medical referral is indicatedMedical referral is indicated constant vertigoconstant vertigo lateralpulsionlateralpulsion facial asymmetryfacial asymmetry speech proprioceptive loss)(abnormal tone proprioceptive loss) VOR gain VOR gain (maintained fixation, dynamic visual acuity)(maintained fixation, dynamic visual acuity) head shaking head shaking (compensated UVL; not necessarily PVL)(compensated UVL; not necessarily PVL) caloricscalorics pressure sensitivity pressure sensitivity (fistula)(fistula) positional nystagmus positional nystagmus (Hallpike-Dix test)(Hallpike-Dix test) hyperventilation hyperventilation (anxiety; acoustic neuroma)(anxiety; acoustic neuroma) NystagmusNystagmus Rapid alternating movement of eyes in Rapid alternating movement of eyes in response to continued rotation of the bodyresponse to continued rotation of the body Primary diagnostic indicator in identifying Primary diagnostic indicator in identifying vestibular lesionsvestibular lesions Physiologic nystagmusPhysiologic nystagmus vestibular, visual, extreme lateral gazevestibular, visual, extreme lateral gaze Pathologic nystagmusPathologic nystagmus spontaneous, positional, gaze evokedspontaneous, positional, gaze evoked Labeled by the direction of the fast Labeled by the direction of the fast componentcomponent Central vs. peripheral cause differentiated by Central vs. peripheral cause differentiated by duration duration Vestibular Function TestsVestibular Function Tests Caloric testCaloric test Rotary Chair testRotary Chair test PosturographyPosturography Results of Vestibular Function Results of Vestibular Function TestsTests Presence of complete vs. incomplete lossPresence of complete vs. incomplete loss Presence of peripheral vs. central Presence of peripheral vs. central dysfunctiondysfunction Direct patient managementDirect patient management Help in outcome predictionHelp in outcome prediction Dizziness Handicap InventoryDizziness Handicap Inventory Three subscalesThree subscales functionfunction emotionemotion physical aspectsphysical aspects ScoringScoring YesYes4 pts.4 pts. Sometimes 2 pts.Sometimes 2 pts. No 0 pts.No 0 pts. Excellent test-retest reliabilityExcellent test-retest reliability Hallpike-Dix ManeuverHallpike-Dix Maneuver Gold standard used to check for the Gold standard used to check for the presence of benign paroxysmal positional presence of benign paroxysmal positional vertigo (BPPV)vertigo (BPPV) Nystagmus induced by this test is an Nystagmus induced by this test is an objective measurement from which we can objective measurement from which we can determine SSC dysfunction and assess a determine SSC dysfunction and assess a response to treatmentresponse to treatment Benign Paroxysmal Positional Vertigo Benign Paroxysmal Positional Vertigo (BPPV)(BPPV) Signs nausealightheadedness; nausea anxietyanxiety avoids movementavoids movement direction reproduced by torsional/linear-rotary nystagmus; reproduced by provocative positioning with affected ear downprovocative positioning with affected ear down nystagmus of 1-5 sec. latency nystagmus of 1-5 sec. latency nystagmus of brief duration (5-30 sec.)nystagmus of brief duration (5-30 sec.) reversal of nystagmus direction on returning to reversal of nystagmus direction on returning to upright positionupright position response diminishes with repetition of maneuver response diminishes with repetition of maneuver (fatigability)(fatigability) ( ( Massoud 96)Massoud 96) BPPVBPPV CupulolithiasisCupulolithiasis Debris, probably fragments of otoconia from Debris, probably fragments of otoconia from the utricle, adhere to the cupulathe utricle, adhere to the cupula TreatmentTreatment Brandt-Daroff habituation exercisesBrandt-Daroff habituation exercises Semont, liberatory maneuverSemont, liberatory maneuver BPPVBPPV CanalithiasisCanalithiasis Debris floating freely in the endolymph in Debris floating freely in the endolymph in the long arm of the posterior SSCthe long arm of the posterior SSC TreatmentTreatment Canalith repositioning maneuver (Canalith repositioning maneuver (Epley)Epley) 84-90% remission rate84-90% remission rate Sleep upright one night only Sleep upright one night only (more severe(more severe cases)cases) Problems Experienced with Problems Experienced with Vestibular LossVestibular Loss Balance in complete loss of alternative strategies/substitution; in complete loss of vestibular functionvestibular function Enhanced by active movements work at limit of abilitieserror signal; work at limit of abilities Incorporation of head movements & visual Incorporation of head movements & visual inputinput Provide context specific stimulation to Provide context specific stimulation to promote adaptationpromote adaptation Adaptation is positively affected by voluntary Adaptation is positively affected by voluntary muscle controlmuscle control (Herdman 2000)(Herdman 2000)