Basic Physiological Principles
• Two types of acceleration sensors:
angular (semicircular canals) and linear (otoliths)
• Two reflexes: vestibulo-ocular reflex (VOR) and vestibulo-spinal reflex (VSR)
• Functions: Assure clear vision during head motion (rotation and translation) and maintain upright posture during standing and walking
Update on the Bedside Evaluation of the Dizzy Patient: the Angular and Transalational Vestibuloocular Reflex
David Zee
The Johns Hopkins University, USA
Innervation and Blood Supply of the Labyrinth: Clinical points
• Anterior vestibular artery is an end artery (hence most susceptible to ischemia). Thus posterior circulation hypoperfusion with isolated vertigois a possibility albeit unusual to recur over the long term without other signs or symptoms.
• Cochlear branch of the common cochlear -- posterior vestibular artery supplies the basal turn of the cochlea (high frequencies). Hence hearing loss in association with ischemic (and inflammatory) processes on the vestibular nerve is usually high frequencywhile with Ménière's disease (endolymphatic hydrops) the hearing loss with vertigo is usually low frequency.
SCC – rostral vestibular complex
OTOLITH – caudal vestibular complex
Central labyrinthine projections
VESTIBULOCEREBELLUM
SCC / Otolith
Central projections from the labyrinth
• SCC projections are primarily to the rostral portions of the vestibular complex.
• Otolith projections are primarily to the caudal portions of the vestibular complex. Beware infarct in lateral medulla (Wallenberg’s syndrome) when symptoms and signs are isolated otolith (tilt, vertical diplopia due to skew (vertical misalignment of eyes).
• SCC and otoliths also project directly to the cerebellum. Beware of cerebellar hemorrhage and infarct in elderly presenting as ‘labyrinthitis’, especially if they CANNOT walk, even with assistance.
SCC Organization: a guide to nystagmus
Peripheral Pattern
Arrows indicate direction of slow phase with stimulation
Central Patterns
Visual-Vestibular Interaction:
convergence of labyrinthine and visual inputs within the vestibular nuclei
Rotation in the dark
Pure visual (optokinetic) input
Why do vestibular patients complain so much in supermarkets, while driving, watching action movies?
There is a strong convergencebetween vestibular and visual signals in the brainstem (vestibular nuclei) and cerebrum (vestibular cortex).
In pathological circumstances, the visual and vestibular signals become incongruent, leading to abnormal sensations of motion and tilt, and discomfort, anxiety and phobias.
Psychiatric disease and vertigo
• Disabling psychological effects of vestibular disease.
– Phobic behavior.
– Anxiety and panic attacks.
– Depression and withdrawal.
• Psychiatric disease presenting with vestibular symptoms
– Somatization and psychosomatic disorders.
– Obsessive compulsive behavior.
– Panic attacks.
– Depression.
Evaluation and treatment of psychiatric symptoms in vestibular patients should proceed in parallel with the ‘organic’ evaluation and treatment
A physiological based exam
• Static disturbances due to a tone imbalance with head still.
• Dynamic disturbances due to abnormal responses duringmotion of the head
Bedside Examination of the SCC – static disturbances
LOCALIZATION OF NYSTAGMUS – Peripheral lesions
– Nystagmus is increased or brought out by removal of fixation (Romberg sign of VOR) – Mixed horizontal-torsional nystagmus is
characteristic for complete loss of function on one side
– Central lesions
– Fixation has little effect on nystagmus – Pure vertical or pure torsional nystagmus
Dynamic Visual Acuity (DVA)
Normal subjects lose only 1 line of acuity with head shaking. Patients with no vestibular function lose about 5 lines with horizontal or vertical rotation but not with rotation in ‘roll’ (ear to shoulder) since the image is still on the fovea. Patients who lose DVA in ‘roll’ are malingering!
Technique to elicit thrusts (rotational VOR) and heaves (translational VOR)
Head-thrust sign in bilateral labyrinthine loss
Catch-up saccades during brief, high- acceleration, head rotation (bilateral loss)
Remember: Patients who lose vestibular function bilaterally do NOT have vertigo since there is no tone imbalance or nystagmus. E.g., ototoxicity of antibiotics
Quantification of t-VOR: ‘Head sled’
Vestibular responses on the ‘head sled’
Normal subject
Cerebellar patient
Pursuit -- Cerebellar patient
Head-shaking induced nystagmus
• Peripheral pattern: slow phase toward affected ear after horizontal head shaking
• Central pattern: vertical nystagmus (usually DB) after horizontal head shaking (cross coupling)
• Note that in Ménières disease the initial slow phase may be toward the intact ear.
Can not use the direction of nystagmus
to decide the affected ear in Ménières
disease. Must use audiogram and hearing.
Congenital Epidermoids
• Usually appear in adolescence
• Males > females
• Hemifacial spasms may precede frank facial palsy
Mechanisms for hyperventilation-induced nystagmus
• Improved conduction on demyelinated fibers (alkalosis, calcium).
• Change in intracranial pressure mediated through a fistula.
• Seizures.
• Ischemia (decreased blood flow).
Recovery nystagmus
• After a unilateral peripheral loss of vestibular function there is a central rebalancing to eliminate the spontaneous nystagmus.
• If peripheral function suddenly “recovers” (e.g., by improved conduction on demyelinated nerves because of pH changes due to hyperventilation), a new imbalance is created causing a recovery nystagmus with slow phases directed away from the affected ear.
Fistula due to
Intact side Abnormal side dehiscence of the roof of the superior SCC
Lloyd
minor
CT temporal bone
0.5mm slices with 3D reconstruction
Beldon, Radiology 2003
Audiograms in superior canal dehiscence
Air-bone gap
Lowered threshold for bone-conducted hearing
Case1
Case2
Vestibular-evoked myogenic potentials (VEMPS)
• Short-latency, relaxation potentials measured from tonically-active sterno- cleido-mastoid muscle that relax with ipsilateral loud clicks.
• Originate from the sacculus (inferior division of vestibular nerve)
• 10 Hz, 0.1ms, 60-103 dB
Syndrome of dehiscence of the roof of the superior canal
• Vertigo, oscillopsia, and/or dysequilibrium related to noise, altered middle ear pressure, exercise and/or altered intracranial pressure (e.g., Valsalva maneuvers, jugular vein compression).
• Changes in symptoms with head position; chronic dysequilibrium.
• Auditory findings
– Gaze-evoked and pulsatile tinnitus
– Hyperacusis – lowered thresholds for bone conduction with air-bone but with normal tympanogram – ‘Malleolus sign’ (hears vibration at ankle!) – Lowered threshold for click-induced EMG of
sternocleidomastoid (VEMPs)
Syndrome of dehiscence of the roof of the superior canal
• Induced vertical-torsional eye movements (with sound or valsava maneuvers) that can be explained by activation of the superior canal.
• Temporal bone CT scans identify dehiscence of bone overlying the affected superior
semicircular canal.
• Beware some normals without symptoms have thin bone.
• Beware false positives (especially with > 0.5mm sections).
• Symptoms relieved by plugging of the superior canal (if necessary).
Migraine and the vestibular
system
Von Brevern, Brain, 2004; Neurology 2004 Furman, JNNP,2005
Neuhauser, Cephalgia, 2004 Crevitz, Clinical Neurology Neurosurgery, 2005
Brantberg, Acta Otolaryngologica, 2005
Some ‘facts’ about vestibular migraine
• In a “dizziness clinic” 38% of patients were diagnosed with migraine (24% in an orthopedics clinic); 7%, with migrainous vertigo, and in a
“migraine clinic”, 9% diagnosed with migrainous vertigo. (Neuhauser).
• Other studies suggest that more than 50% of migraineurs have vestibular symptoms (including dizziness)!
• In patients with dizziness and migraine,
abnormalities on vestibular lab testingare common, but often nonspecific.
– up to 25% of migraineurs with dizziness have been reported to have a reduced caloric response. (CAUTION ADVISED HERE).
– Interictal, central eye movement abnormalities (e.g., gaze-evoked nystagmus, impaired pursuit) have been
Some ‘facts’ about vestibular migraine
• The mean onset of vertigo in migraine is about 40 yrs of age, and headaches precede vertigo by almost 10 years. Women much more likely to be diagnosed with vertigo and migraine.
• Duration of symptoms is usually minutes to a day but ‘low-level’ symptoms may last days to weeks – imbalance and extreme motion sensitivity
• Patient may have hearing symptoms; muffled sounds, ear pressure or pain, tinnitus.
• Patients overall often have chronic motion sensitivity. (Syndrome of mal de debarquement).
• Migraine headaches are often an infrequent or long-forgotten symptom in vestibular migraine.
Some ‘facts’ about vestibular migraine
• Family history is usually positive and attacks of vertigo may be the predominant symptom in some family members.
• Light sensitivity is common in migraineurs during their attacks of vertigo.
• Panic, anxiety and phobic behavior are common in patients with vertigo and migraine.
Differential diagnosis of vestibular migraine
• Vestibular neuritis, neuronitis, labyrnthitis, neurolabyrinthits
– Isolated attackof acute vertigo, nausea, dysequilibrium, previous URI.
– Head thrust sign with abnormal caloric response.
– May be viral (Rx, with prednisone and antivirals) or ischemic (relative poor collateral circulation to the structures perfused by the anterior vestibular artery (supplies the lateral semicircular canal)).
– Remember inflammatory disorders (e.g., Lyme, Syphilis).
– (A first and severe attack of vestibular migraine may be difficult to distinguish from above)
• Benign Paroxysmal Positional Vertigo (BPPV); perhaps triple the incidence in migraine patients.
Differential diagnosis of vestibular migraine
• Ménière's disease
– Pain, pressure, fullness in ear, loss of hearing which may precedes vertigo and aural symptoms may disappear with vertigo (Lermoyez syndrome).
– Fluctuating tinnitus, low-pitched, sea-shell.
– Fluctuating hearing loss, often low-frequency. GET AUDIOGRAMS
– Attacks of vertigo, hours to a day or two.
– Otolithic crises of Tumarkin – patient is suddenly thrown to the ground.
– May be due to autoimmune disease or as a late sequela of inner ear viral infection.
–Transtympanicelectrocochleography (ECOG).
Increased co-morbidity with migraine (Radtke).
– Vertigo attacks can be effectively treated with intratympanic gentamicin BUT be sure of dx.
– “Vestibular Ménière's” is commonly migraine.
Differential diagnosis of vestibular migraine
• Remember episodic ataxia 2(EA2) – familial, periodic, diamox-responsive vertigo and ataxia (calcium channel on chromosome 19, as is familial hemiplegic migraine).
– Onset relatively young in life.
– Precipitated by emotion or exercise.
– Eventually develop interictal downbeat nystagmus and other cerebellar eye signs.
• Temporal lobe epilepsy(tornado epilepsy), especially in children.
• Variety of central disorders – Tumors in the posterior fossa,
– Cranio-cervical junction anomalies (Chiari malformation) –Valsalva-induced symptoms.
– Demyelination.
– Posterior circulation ischemia – Vertebral artery dissection.
Differential diagnosis of vestibular migraine
• Microvascular compression (VIII) syndrome
– paroxysms (seconds) of tinnitus or vertigo, – sustained motion sensitivity,
– chronic dysequilibrium, – positionally-induced symptoms, – hyperventilation-induced nystagmus, – abnormal BAER.
– respond to AED.
Differential diagnosis of vestibular migraine
• Perilymphatic fistula
– post-traumatic or spontaneous and also associated with congenital temporal bone anomalies (e.g., Mondini).
–Hearing lossis usually prominent. Chronic dysequilibrium.
– May have positional symptoms.
• Large vestibular aqueduct syndrome
– early onset hearing loss recurrent vertigo.
– often precipitated by exercise or mild head trauma.
DDx of Vestibular Migraine
• Meniere’s syndrome
• Acute labyrinthitis (viral,ischemic)
• BPPV (high incidence in migraine)
• Episodic ataxia and vertigo (EA1)
• ‘Tornado epilepsy’
• Miscellaneous – MS, vestibular schwannoma, autoimmune, infection, posterior circulation (dissection, tia), temporal bone abnormalities (dehiscence and large vestibular aqueduct syndrome), microvascular compression, perilymphatic fistula, Chiari malformation and other posterior fossa lesions
Treatment of vestibular migraine
• EDUCATION (e.g., educational video)
• Appropriatephysical therapy – e.g., Tai Chi exercises.
• Eliminate provocatives, e.g. diet??
• Psychological management (stress, depression)
• The usual migraine prophylactics (AEDs) – Neurontin, topiramate, depakote, oxycarbamazepine??
– Triptans ??
– Tricyclics, beta blockers, calcium channel blockers??
• Acetazolamide??
• Benzodiazepams??
Benign Paroxysmal Positional Vertigo (BPPV)
• Easily diagnosed by history and exam
• Pathophysiology well understood
• Easily treated
• Patients gratified
Benign Paroxysmal Positional Vertigo (BPPV)
• Posterior SCC becomes gravity sensitive due to floating debris (otoconia dislodged from the macula of the utricle)
• Otoconia get trapped in the posterior SCC on the cupula
(CUPULOLITHIASIS)or are free-floating in the long arm of the canal (CANALOLITHIASIS).
Otoconia in BPPV
(CUPULOLITHIASIS) Otoconia in BPPV
(CANALOLITHIASIS)
BPPV: Otoconia in posterior SCC
From intact otolith From SCC in BPPV patient
at the time of surgery
BPPV -- Etiology
• Idiopathic (especially elderly)
• Post traumatic (may be mild, e.g.
whiplash, riding a bicycle on rough terrain)
• Prolonged bed rest or unusual postures (hair dresser, dentist, working under one’s car)
• Post labyrinthitis (viral or ischemic) which spares the inferior division of the vestibular nerve (posterior SCC intact)
BPPV -- Symptoms
• Transient vertigo precipitated by a change in attitude of the head relative to gravity (offending ear down, e.g., turning over in bed, looking to a high shelf, getting out of or into bed), or by exposure to imposed linear acceleration (elevator, car)
• Tumbling, rolling, cartwheeling sensation, with nausea, vomiting and imbalance
• Chronic unsteadiness
• Symptoms typically maximum for days to weeks, usually resolves in months, but often recurs
BPPV -- Signs
• Mixed vertical-torsional nystagmus, slow phases downwards and top of eyes roll away from offending (dependent) posterior SCC.
• Elicited in the Dix-Hallpike maneuver (head turned 45 deg then body and head moved en bloc straight back).
• Nystagmus more vertical when looking toward the up ear, and more torsional when looking toward the down ear.
• Latency (up to 30sec), transient (usually less than 15sec), decreases with repetitive testing.
• Reverses direction on sitting up.
• If cupulolithiasis, more sustained, less
Nystagmus in BPPV from right SCC
Direction of Slow-phase
BPPV – Treatment for posterior SCC variant
• Do nothing -- avoid offending position
• Epley maneuver -- Roll of head from offending ear down to offending ear up.
• Semont maneuver – 180 deg cartwheel of torso from offending ear down and nose up to offending ear up and nose down, slow rise.
Post-treatment instructions
• Do not bend over or look up for rest of the day.
Keep head in neutral position
• Watch for sudden transient imbalance immediately after treatment
• Sit still in clinic for about 20 minutes before walking away
• Avoid sleeping on offending side for several nights.
• Retreatment in one week for 20-30% of cases
• Home exercise program
– Web site http:www.charite.de/ch/neuro/vertigo.htm
• Almost never necessary is surgery -- canal plugging, singular nerve section
Treatment exercises for left BPPV Treatment exercises for right BPPV
Lateral canal BPPV
Von Brevern Neurology,
2001
Lateral canal BPPV
• Elicit in ‘Barany position”, right or left ear down.
• Geotropic, direction-changing (beats to the ground) (usually canalolithiasis). More intense with affected ear down.
• Apogeotropic, direction changing (beats to the sky) (occasionally cupulolithiasis).
More intense with affected ear up.
Lateral canal BPPV
• If canalolithiasis (on cupula) may have small spontaneous nystagmus with eyes in straight ahead position (slow phase toward affected ear) with head upright.
• There may be a null with head slightly pitched forward.
• If supine and turn to either side, the null is toward the affected side.
Treatment -- Lateral canal BPPV
– Log rolling (toward intact side).– Single, repositioning maneuver.
– Lie for 11 hours with affected side up.
– Note, if ‘iatrogenic’, i.e., after repositioning maneuver for posterior canal BPPV, usually disappears spontaneously in a day or two.
Treatment of lateral canal (geotropic, beats toward the ground) BPPV
Tilt OPPOSITE the affected side
Casini, Laryng, 2002
Rx of right-sided apogeotropic (beats
toward the sky) lateral canal BPPV Tilt TOWARD the
affected side
Orientation of canals in left labyrinth with head upright*
Bertholon JNNP 2002
Anterior canal BPPV
• Downbeat nystagmus with torsional component (may be small).
• Elicited in both Dix-Hallpike positions and especially with head hanging.
• Exclude central problems (cerebellar lesions and multisystem atrophy (MSA)).
• Treatment??
Anterior canal BPPV producing vertical nystagmus with head in either Dix-Hallpike
position*
Bertholon JNNP 2002
