Vestibular Function and Anatomy Prof. Hamad Al-Muhaimeed Professor/Consultant Department of Otorhinolaryngology King Abdulaziz University Hospital

System of balance System of balance Membranous and bony labyrinth embedded in petrous bone Membranous and bony labyrinth embedded in petrous bone 5 distinct end organs 5 distinct end organs –3 semicircular canals: superior, lateral, posterior –2 otolith organs: utricle and saccule

Semicircular canals sense angular acceleration Semicircular canals sense angular acceleration Otolithic organs (utricle and saccule) sense linear acceleration Otolithic organs (utricle and saccule) sense linear acceleration

Embryology 3rd week of embryonic development 3rd week of embryonic development Otic placode formed from neuroectoderm and ectoderm Otic placode formed from neuroectoderm and ectoderm Otocyst or otic vesicle 4th week Otocyst or otic vesicle 4th week

Semicircular canals are orthogonal to each other Semicircular canals are orthogonal to each other Lateral canal inclined to 30 degrees Lateral canal inclined to 30 degrees Superior/postereor canals 45 degrees off of sagittal plane Superior/postereor canals 45 degrees off of sagittal plane

Utricle is in horizontal plane Utricle is in horizontal plane Saccule is in vertical plane Saccule is in vertical plane

Anatomy

There are five openings into area of utricle There are five openings into area of utricle Saccule in spherical recess Saccule in spherical recess Utricle in elliptical recess Utricle in elliptical recess

45% from AICA 45% from AICA 24% superior cerebellar artery 24% superior cerebellar artery 16% basilar 16% basilar Two divisions: anterior vestibular and common cochlear artery Two divisions: anterior vestibular and common cochlear artery

Superior vestibular nerve: superior canal, lateral canal, utricle Superior vestibular nerve: superior canal, lateral canal, utricle Inferior vestibular nerve: posterior canal and saccule Inferior vestibular nerve: posterior canal and saccule

Membranous labyrinth is surrounded by perilymph Membranous labyrinth is surrounded by perilymph Endolymph fills the vestibular end organs along with the cochlea Endolymph fills the vestibular end organs along with the cochlea

Perilymph Perilymph –Similar to extracellular fluid –K+=10mEQ, Na+=140mEq/L –Unclear whether this is ultrafiltrate of CSF or blood –Drains via venules and middle ear mucosa

Endolymph Endolymph –Similar to intracellular fluid –K+=144mEq/L, Na+=5mEq/L –Produced by marginal cells in stria vascularis from perilymph at the cochlea and from dark cells in the cristae and maculae –Absorbed in endolymphatic sac which connected by endolymphatic, utricular and saccular ducts

Sensory structures Ampulla of the semicircular canals Ampulla of the semicircular canals Dilated end of canal Dilated end of canal Contains sensory neuroepithelium, cupula, supporting cells Contains sensory neuroepithelium, cupula, supporting cells

Cupula is gelatinous mass extending across at right angle Cupula is gelatinous mass extending across at right angle Extends completely across, not responsive to gravity Extends completely across, not responsive to gravity Crista ampullaris is made up of sensory hair cells and supporting cells Crista ampullaris is made up of sensory hair cells and supporting cells

Sensory cells are either Type I or Type II Sensory cells are either Type I or Type II Type I cells are flask shaped and have chalice shaped calyx ending Type I cells are flask shaped and have chalice shaped calyx ending One chalice may synapse with 2-4 Type I cells One chalice may synapse with 2-4 Type I cells Type II cells – cylinder shaped, multiple efferent and afferent boutons Type II cells – cylinder shaped, multiple efferent and afferent boutons

Hair cells have stereocilia and a single kinocilium.

stereocilia are not true cilia, they are graded in height with tallest nearest the kinocilium.

Otolithic organs Utricle and saccule sense linear acceleration Utricle and saccule sense linear acceleration Cilia from hair cells are embedded in gelatinous layer Cilia from hair cells are embedded in gelatinous layer Otoliths or otoconia are on upper surface Otoliths or otoconia are on upper surface

Calcium carbonate or calcite Calcium carbonate or calcite um um Specific gravity of otolithic membrane is Specific gravity of otolithic membrane is Central region of otolithic membrane is called the striola Central region of otolithic membrane is called the striola

Saccule has hair cells oriented away from the striola Saccule has hair cells oriented away from the striola Utricle has hair cells oriented towards the striola Utricle has hair cells oriented towards the striola Striola is curved so otolithic organs are sensitive to linear motion in multiple trajectories Striola is curved so otolithic organs are sensitive to linear motion in multiple trajectories

Senses and controls motion Senses and controls motion Information is combined with that from visual system and proprioceptive system Information is combined with that from visual system and proprioceptive system Maintains balance and compensates for effects of head motion Maintains balance and compensates for effects of head motion

DEFINITION & TERMINOLOGIES

VERTIGO (illusion of rotational, linear or tilting movement such as “spinning”, “whirling” or “turning” of the patient or the surrounding. DISEQUILBRIUM sensation of instability of the body positions, walking or standing described as “off balanced” or “imbalanced”. VERTIGO (illusion of rotational, linear or tilting movement such as “spinning”, “whirling” or “turning” of the patient or the surrounding. DISEQUILBRIUM sensation of instability of the body positions, walking or standing described as “off balanced” or “imbalanced”.

DEFINITION & TERMINOLOGIES OSCILLOPSIA (inability to focus on objects with motion, such as reading a sign while walking, seen with bilateral or central vestibular loss). OSCILLOPSIA (inability to focus on objects with motion, such as reading a sign while walking, seen with bilateral or central vestibular loss).

DEFINITION & TERMINOLOGIES LIGHTHEADEDNESS (sense of impending faint, presyncope). LIGHTHEADEDNESS (sense of impending faint, presyncope). PHYSIOLOGIC DIZZINESS (motion sickness, height vertigo), PHYSIOLOGIC DIZZINESS (motion sickness, height vertigo),

EVALUATION OF THE DIZZY PATIENT History History Dizziness is a term used to describe any of a variety of sensation that produce spatial disorientation. Dizziness is a term used to describe any of a variety of sensation that produce spatial disorientation. Onset and Duration of Symptoms: Onset and Duration of Symptoms:

EVALUATION OF THE DIZZY PATIENT History History Character of Dizziness: Character of Dizziness: Contributing Factors: Contributing Factors: Associated Symptoms: Associated Symptoms:

PHYSICAL EXAMINATION H & N and General Physical Exam: H & N and General Physical Exam: Otoscopy: Otoscopy: Vestibular Testing: Vestibular Testing: Neurological Exam: Neurological Exam:

General Characteristics of Peripheral and Central Causes of Vertigo CharacteristicPeripheralCentral Intensityseveremild Fatigabilityfatigues,does not Associatedadaptationfatigue

General Characteristics of Peripheral and Central Causes of Vertigo CharacteristicPeripheralCentral Symptomsnausea,weakness, hearing loss,numbness sweatingfalls more likely Eye closed symptom, symptoms worse with better with eyes closed eyes closed

General Characteristics of Peripheral and Central Causes of Vertigo CharacteristicPeripheralCentral Nystagmus horizontal, may vertical be unilateralbilateral rotary Ocular suppresses no effect Fixationnystagmus (may or enhances not suppressnystagmus during acute phase )

CAUSES OF VERTIGO PERIPHERAL VERTIGO: Benign Paroxysmal Positional Vertigo Benign Paroxysmal Positional Vertigo Meniere Disease Meniere Disease Vestibular Neuronitis Vestibular Neuronitis Perilymphatic Fistulas Perilymphatic Fistulas

CAUSES OF VERTIGO CENTRL CAUSES Cerebellospontine Angle Tumuors Cerebellospontine Angle Tumuors Traumatic Vestibular Dysfunction Traumatic Vestibular Dysfunction

CENTRAL AND SYSTEMIC CAUSES OF VERTIGO Multiple Sclerosis Multiple Sclerosis Other Neurological Disorder (stroke, seizures, middle cerebellar lesions, parkinsonism, psudobulbar palsy) Other Neurological Disorder (stroke, seizures, middle cerebellar lesions, parkinsonism, psudobulbar palsy) Metabolic Disorders (hypo/hyper- Metabolic Disorders (hypo/hyper- thyroidism, diabetes) thyroidism, diabetes)

CENTRAL AND SYSTEMIC CAUSES OF VERTIGO Medications and Intoxicants (psychotropic drugs, alcohol, analgesics, anesthetics, antihypertensives, anti-arrhythmics, chemotherapeutics) Medications and Intoxicants (psychotropic drugs, alcohol, analgesics, anesthetics, antihypertensives, anti-arrhythmics, chemotherapeutics) Vascular Causes (vertebrobasilar insufficiency, basilar migraine syndrome, vascular loop compression syndrome) Vascular Causes (vertebrobasilar insufficiency, basilar migraine syndrome, vascular loop compression syndrome)

VESTIBULAR TESTING HALLPIKE TEST HALLPIKE TEST ELECTRONYSTAGMOGRAPHY ELECTRONYSTAGMOGRAPHY ROTATION TEST OCULOMOTOR TESTING ROTATION TEST OCULOMOTOR TESTING POSTUGRAPHY POSTUGRAPHY

CALORIC TESTING Only test that evaluates vestibular function in each ear independently, determines unilateral versus bilateral weakness Only test that evaluates vestibular function in each ear independently, determines unilateral versus bilateral weakness Technique: Technique: Theoretical Normal Response: Theoretical Normal Response:

CALORIC TESTING Directional Preponderance: Directional Preponderance: Unilateral Caloric Weakness: Unilateral Caloric Weakness: Bilateral Weakness: Bilateral Weakness:

DIAGNOSIS Based on clinical history, physical examination and audiological findings (initial low-frequency SNHL) with exclusion of other causes of hearing loss and vertigo is adequate for diagnosis and initiating empirical therapy. Based on clinical history, physical examination and audiological findings (initial low-frequency SNHL) with exclusion of other causes of hearing loss and vertigo is adequate for diagnosis and initiating empirical therapy.

Meniere’s Disease (Endolymphatic Hydrops ) Signs and Symptoms Episodic Vertigo lasting minutes to hours Episodic Vertigo lasting minutes to hours Episodic fluctuating SNHL (usually unilateral), recovery between episodes may be incomplete resulting in a progressive SNHL (initially at lower frequencies) Episodic fluctuating SNHL (usually unilateral), recovery between episodes may be incomplete resulting in a progressive SNHL (initially at lower frequencies) Tinnitus and episodic fullness associated with or without the hearing loss Tinnitus and episodic fullness associated with or without the hearing loss

Meniere’s Disease (Endolymphatic Hydrops) Signs and Symptoms Classic Menieres Disease presents with all of the above symptoms (vertigo, hearing loss, tinnitus, and aural fullness), however Meniere Disease may also present as any combination of the above symptoms Classic Menieres Disease presents with all of the above symptoms (vertigo, hearing loss, tinnitus, and aural fullness), however Meniere Disease may also present as any combination of the above symptoms

Meniere’s Disease (Endolymphatic Hydrops) DIAGNOSIS DIAGNOSIS Vestibular testing may reveal unilateral weakness on affected side. Vestibular testing may reveal unilateral weakness on affected side. Electrocochleography: Electrocochleography:

MEDICAL MANAGEMENT OF MENIERE DISEASE Dietary Restrictions: Dietary Restrictions: Diuretics: Diuretics: Vestibular Suppressants: Vestibular Suppressants: Corticosteroids: Corticosteroids: Allergy Management: Allergy Management: Stress Reduction Stress Reduction

BENIGN PAROXYSMAL POSITIONAL VERTIGO (BPPV, Cupulolithiasis)

BPPV Frequency- 50% of peripheral vertigo, 20% of pts over 80 have BPPV Frequency- 50% of peripheral vertigo, 20% of pts over 80 have BPPV Clinical history: sudden onset, brief vertigo, brought on by changes in head position, particularly turning in bed, or tilting head back, may have prior history of vestibular neuritis or head trauma Clinical history: sudden onset, brief vertigo, brought on by changes in head position, particularly turning in bed, or tilting head back, may have prior history of vestibular neuritis or head trauma Exam: + Dix-Hallpike (don’t forget 5-10% have horizontal variant) Exam: + Dix-Hallpike (don’t forget 5-10% have horizontal variant) Pathophysiology: loose calcium crystals in posterior semicircular canal Pathophysiology: loose calcium crystals in posterior semicircular canal Treatment: Epley manuever Treatment: Epley manuever

MANAGEMENT Education, reassurance and observation Education, reassurance and observation Particle Repositioning Maneuver (Epley’s Maneuver): Particle Repositioning Maneuver (Epley’s Maneuver): Home vestibular positional exercises Home vestibular positional exercises Antivertiginous medications Antivertiginous medications Singular Neurectomy: Singular Neurectomy:

Vestibular Neuritis Frequency: 15% of peripheral vertigo Frequency: 15% of peripheral vertigo Clinical history: sudden onset severe vertigo c N/V, sx’s improve in days to weeks secondary to central compensation, can have chronic effects for months to years. Clinical history: sudden onset severe vertigo c N/V, sx’s improve in days to weeks secondary to central compensation, can have chronic effects for months to years. Exam: unilateral nystagmus c fast phase away from affected ear, amplitude of nystagmus decreases when looking towards affected ear, +/- hearing loss or tinnitus Exam: unilateral nystagmus c fast phase away from affected ear, amplitude of nystagmus decreases when looking towards affected ear, +/- hearing loss or tinnitus Pathophysiology: probably secondary to viral infection & inflammation of vestibular nerve or labyrinth Pathophysiology: probably secondary to viral infection & inflammation of vestibular nerve or labyrinth Treatment: steroids- 3 week tapering course, starting at 100 mg. Treatment: steroids- 3 week tapering course, starting at 100 mg. –Strupp et al. (2004). Methylprednisolone, Valacyclovir, or the Combination for Vestibular Neuritis. NEJM 351, pp

PERILYMPH FISTULA Pathophysiology: Pathophysiology: Causes: Causes: SSx: SSx: Diagnosis: Diagnosis: Treatment: Treatment:

VERTEBRONBASILAR INSUFFICIENCY (VBI) Pathophysiology: Pathophysiology: SSx: SSx: Diagnosis: Diagnosis: Treatment Treatment

OTHER VESTIBULAR DISORDERS Basilar Migraine Syndrome: Basilar Migraine Syndrome: Vestibular Epilepsy: Vestibular Epilepsy: Multiple Sclerosis (MS): Multiple Sclerosis (MS): Labyrinthine Apoplexy: Labyrinthine Apoplexy: Subclavian Steal Syndrome: Subclavian Steal Syndrome: Hyperrinsulinemia/Diabetes: Hyperrinsulinemia/Diabetes:

Etiology Recur Onset Duration Associated features BPPV + sudden <1 min elderly, induced by position change Meniere’s + gradual hours ear fullness, tinnitus, low freq hearing loss Vestibular - gradual days-weeks 50% c preceding viral neuritis or suddenillness, +/- hearing loss Migraine + gradual sec-days young F, HA, positive visual phenomenon VB TIA + sudden mins CN, long-tract sx’s/ signs Labryinth - sudden days-months hearing stroke loss +/- tinnitus Brainstem - sudden days-months CN, long-tract strokesx’s/ signs Cerebellar - sudden days-months unil dysmetria, stroke “central” nystagmus

MANAGEMENT CONCEPT Safety: Safety: Acute Vestibular Suppression: Acute Vestibular Suppression: Vestibular Rehabilitation: Vestibular Rehabilitation: Surgical Management: Surgical Management:

SURGICAL MANAGEMENT OF VERTIGO

Endolymphatic Sac Surgery: Endolymphatic Sac Surgery: Vestibular Nerve Section: Vestibular Nerve Section: Transtympanic Or Intratympanic Aminoglycoside Injections: Transtympanic Or Intratympanic Aminoglycoside Injections: Labyrinthectomy Labyrinthectomy

Conclusion 1. Is this vertigo? 2. Is this central or peripheral? 3. History- focus on age, PMH, duration 4. Exam- focus on CN and coordination, focal neurological findings, Dix-Hallpike