Bells Palsy

Bell's Palsy and Cranial Nerve Injuries

Bell's Palsy

  • AKA "idiopathic peripheral facial paralysis"

  • Most common peripheral paralysis of the seventh cranial nerve

  • Rapid and unilateral onset

  • Causes weakness of one half of the face, changes in taste, sensitivity to sound, and alteration in lacrimation and salivation

  • Affects 11-40 persons per 100,000 each year

  • Peak incidence usually between the ages of 15 and 50 years

  • Etiology includes pregnancy, postpartum periods, diabetes, hypothyroidism, familial origin, idiopathic, traumatic, neoplastic, congenital, and autoimmune causes

  • Pathology includes acute demyelinating disease, latent herpes viral infections, and infectious causes

  • Clinical manifestation includes sudden and rapid onset of unilateral facial weakness, preceding viral illness, earache, hyperacusis, tinnitus, taste disturbances, and decreased lacrimation

  • Lesion manifestations include facial weakness, impaired taste and salivation, hyperacusis, reduced lacrimation, and involvement of other cranial nerves

  • Bell's phenomenon is the upward movement of the eye on attempted closure of the lid

  • Synkinesis is an important sequelae of facial nerve palsy, causing abnormal involuntary facial movement

  • Crocodile tears, Marcus Gunn phenomenon, inverse Marcus Gunn phenomenon, and Marin-Amat phenomenon are examples of synkinesis

  • Crocodile tears refer to shedding of tears while eating or drinking

  • Marcus Gunn phenomenon is the elevation of ptotic eye in response to sucking, chewing, or mouth opening

  • Inverse Marcus Gunn phenomenon is the upper lid falling to cover the eye in response to sucking, chewing, or mouth opening

  • Marin-Amat syndrome is the upper lid falling to cover the eye in response to opening or lateral movement of the jaw

  • Diagnosis is based on clinical criteria and the House-Brackmann Scale

  • Laboratory and imaging studies are not routinely needed

  • Serological tests may be done to rule out Lyme disease

  • Electromyography and motor nerve conduction can estimate the amount of axonal loss

  • Ramsay-Hunt syndrome is a peripheral facial nerve palsy accompanied by an erythematous vesicular rash on the ear or in the mouth

  • Other differential diagnoses include CNS neoplasms, stroke, HIV infection, multiple sclerosis, Guillain-Barré syndrome, Melkersson-Rosenthal syndrome, Lyme disease, otitis media, cholesteatoma, sarcoidosis, trauma to the facial nerve, and autoimmune diseases

  • Prognosis varies, with normal function returning within 3 weeks to 9 months

  • Complications include corneal dryness leading to visual loss and permanent damage to the facial nerve

  • Management includes protecting the cornea, corticosteroids, acupuncture, physical therapy, electrical nerve stimulation, and surgical decompression

Cranial Nerve Injuries

  • Olfactory nerve is located on the ventral surface of the frontal lobe and is responsible for olfaction (smell)

  • Anosmia is the loss of olfaction and can be caused by basilar skull fracture, CSF rhinorrhea, or halo sign

Medical Information about Cranial Nerve Injuries

Page 5

  • Optic Nerve

    • Location: Ventral surface of the frontal lobe

    • Central connection: Occipital lobe and Diencephalon (thalamus — Lateral Geniculate Body)

    • Exit: Optic Foramen

    • Terminates: Retina

    • Function: Vision (SSA)

  • Clinical Correlation

    • Central Vision Affectation:

      • Cataract — increase opacity of the lens

      • Presbyopia — impaired vision secondary to aging

      • Myopia — Far sightedness / Impaired near vision

      • Hyperopia — Near sightedness / impaired far vision

  • Visual Pathway

    • Monocular blindness

    • Bitemporal hemianopsia

    • C/L Homonymous hemianopsia

Page 6

  • Oculomotor Nerve

    • Location: Midbrain

    • Central connection: Midbrain

    • Exit: Superior orbital fissure

    • Terminates: superior, middle, inferior recti muscle; ciliary, sphincter muscle, levator palpebrae Superioris, inferior oblique

    • Function: moves the eyeball, lift the eyelid, regulate size of the pupil (GSE)

  • Medial rectus muscle

    • Adducts the eye; with its opposite partner, converges the eyes.

  • Superior rectus muscle

    • Elevates, intorts, and adducts the eye

  • Inferior rectus muscle

    • Depresses, extorts, and adducts the eye

  • Inferior oblique muscle

    • Elevates, extorts, and abducts the eye

  • Levator palpebrae muscle

    • Elevates the upper lid → Edinger—Westphal nucleus (GVE)

    • AKA accessory oculomotor nucleus

    • Parasympathetic pre-ganglionic nucleus that innervates the iris sphincter muscle and the ciliary muscle → Ciliary ganglion: (GVE)

    • Projects postganglionic parasympathetic fibers to the sphincter muscle of the iris (miosis) and to the ciliary muscle (accommodation)

Page 7

  • Trochlear Nerve

    • Location: Midbrain

    • Central connection: Posterior aspect of midbrain

    • Exit: Superior orbital fissure

    • Terminates: Superior Oblique

    • Function: moves the eyeball (GSE)

  • Abducens Nerve

    • Location: Pons

    • Central connection: Pons

    • Exit: Superior orbital fissure

    • Terminates: Lateral Rectus

    • Function: moves the eyeball (GSE)

  • Cardinal Gaze Pupillary Light Reflex

    • Afferent: CN2

    • Efferent: CN3

    • Direct and Consensual light

Page 8

  • Normal response of Pupillary Light Reflex

    • Direct light reflex: constriction of the pupil when light is presented on the I/L side

    • Consensual light reflex: constriction of the pupil when the light is presented on the C/L side

  • Accommodation Reflex

    • Afferent: CN2

    • Efferent: CN3

    • Focusses from a distant to near object

    • Constriction of the pupil

    • Thickening of the lens (constriction of ciliary muscle)

    • Convergence of both eyes

  • Trigeminal Nerve

    • Location: Pons

    • Central connection: Pons

    • Exit: Superior orbital fissure (V1); Foramen Rotundum (V2); Foramen Ovale (V3)

    • Terminates: Muscle of mastication, skin and mucus membrane of the face

    • Function: mastication (SVE), sensory to the face (GSA)

  • Divisions of CN V

    • V1 - Opthalmic Nerve - Sensory

    • V2 —- Maxillary Nerve - Sensory

    • V3 -—- Mandibular Nerve — Sensory and Motor*

  • Muscles of Mastication

    • Temporalis

    • Internal/Medial Pterygoid

    • Masseter

    • External/Lateral Pterygoid

  • Corneal Reflex

    • Afferent: CNV1 (Opthalmic Nerve)

    • Efferent: CN7

Page 9

  • Clinical Correlation

    • Loss of general sensation from the face and mucous membranes of the oral and nasal cavities, anterior 2/3 of tongue

    • Loss of the corneal reflex

    • Flaccid paralysis of the muscles of mastication

    • Deviation of the jaw to the weak side due to the unopposed action of the opposite lateral pterygoid muscle

    • Paralysis of the tensor tympani, leading to hyperacusis

  • Vestibulocochlear Nerve

    • Location: Pons

    • Central connection: Pons, Medulla, Temporal lobe

    • Exit: Internal Acoustic Meatus

    • Terminates: Organ of corti, Macula, Crista Ampularis

    • Function: Auditory (SSA) and Equilibrium (SSA)

  • Clinical Correlation

    • Conduction Deafness — Anatomy of The Ear Conducting system

    • Sensorineural Hearing Loss — CN VIII

    • Cortical Hearing Loss – BA 41,42 (Heschl Gyrus)

Page 10

  • Assessment of Vestibulocochlear Nerve

    • Sense of hearing: Weber vs Rinne test

    • Sense of balance: Equilibrium Test

  • Glossopharyngeal Nerve

    • Location: Medulla

    • Central connection: Medulla (posterior (dorsal) lateral sulcus

    • Exit: Jugular foramen

    • Terminates: back of the tongue, pharynx, parotid gland, carotid sinus

    • Function: secretion of the parotid glands (GVE), sensory to the posterior 1/3 of the tongue (SVA and GVA)

  • Vagus Nerve

    • Location: Medulla

    • Central connection: Medulla (posterior (dorsal) lateral sulcus

    • Exit: Jugular foramen

    • Terminates: pharynx, larynx, thoracic and abdominal viscera

    • Function: motor to cardiac, smooth muscles (pharynx and larynx — vocal chords) and glands (GVE); sensory to epiglottis, pharynx, larynx, epiglottis (GVA), skin of the external ear (pinna) (GSA)

  • Assessment of Glossopharyngeal Nerve: Sensory Function

    • Special sensation: Sense of taste on the posterior 1/3

    • General Sensation: light touch, pressure sensation on the posterior 1/3

  • Gag Reflex

    • Aka “Pharyngeal Reflex”/ “Laryngeal Reflex”

    • Afferent: CN 9

    • Efferent: CN10

Page 11: Spinal Accessory Nerve and Hypoglossal Nerve

  • Spinal Accessory Nerve

    • Location: Medulla

    • Central connection: Medulla (posterior (dorsal) lateral sulcus)

    • Exit: Jugular foramen and Foramen Magnum

    • Terminates:

      • Cranial Portion: muscles of the pharynx and larynx (connects with vagus nerve)

      • Spinal Portion: SCM and Trapezius

    • Function:

      • Movement of pharynx and larynx (GVE)

      • Shoulder and neck movement (GSE)

    • Clinical correlation:

      • Scapular Winging

      • Weakness of the trapezius and SCM

  • Hypoglossal Nerve

    • Location: Medulla

    • Central connection: Medulla (Anterior (ventral) lateral sulcus)

    • Exit: Hypoglossal canal

    • Terminates: muscles of the tongue

    • Function: movement of the tongue (SVE)

    • Muscles of the tongue:

      • Palatoglossus — pharyngeal plexus (CN 9 and 10)

      • Genioglossus — CN 12

      • Hyoglossus— CN 12

      • Styloglossus— CN 12

    • Hypoglossal Nerve Palsy:

      • Deviation of the tongue upon protrusion towards the weak side

Page 12: Peripheral and Central Vestibular System

  • Peripheral Vestibular System

    • Semicircular Canals:

      • Detect head acceleration

      • Endolymph moves freely within each canal in response to the direction of the angular head rotation

      • Cupula in the ampulla contains mechanosensing cilia and hair cells

    • Otolith Organs:

      • Saccule (Vertical) and utricle (Horizontal)

      • Detect linear acceleration and static head tilt

      • Sensitive to gravity

      • Contains calcium carbonate crystalline-structure material (otoconia)

  • Central Vestibular System

    • Brain stem processes provide primary control of many vestibular reflexes

    • Vestibular cortex, thalamus, and reticular formation enable the vestibular system to contribute to the integration of arousal and conscious awareness of the body, as well as to discriminate between movement of self and the environment

Page 13: Physiology and Motor Control

  • Tonic Firing Rate

    • Resting firing rate: 70 to 100 spikes/sec

    • Head motion through excitation or inhibition

  • Vestibulo-Ocular Reflex

    • Responsible for maintaining stability of an image on the fovea of the retina during rapid head movements

    • Activates eye muscles to create eye movements in the exact speed but opposite direction of head movements

  • Push—Pull Mechanism

    • Brain detects head movement and direction through comparison of inputs between the two vestibular systems

    • SCCs work in coplanar fashion

    • Increased firing rate in the SCC on the same side as head turn, and decreased firing rate in the opposite SCC

    • I/L (ipsilateral) leads to depolarization, C/L (contralateral) leads to hyperpolarization

  • Inhibitory Cutoff

    • Inhibition of the hair cells in the opposite labyrinth can only reduce the firing rate to zero, at which point the inhibition is cut off

Page 14: Evaluation and Identification of Symptoms

  • Identification of Symptoms

    • Dizziness: categorized as vertigo, lightheadedness, dysequilibrium, or oscillopsia

    • Causes of dizziness: cardiovascular system, neurologic system, vision dysfunction, psychogenic dizziness, cervicogenic dizziness, vestibular system dizziness

    • Vertigo: illusion of movement, episodic and indicates pathology along the vestibular pathways

    • Light-headedness: feeling of fainting, caused by non-vestibular factors

    • Dysequilibrium: sensation of being off balance, associated with vestibular and nonvestibular problems

    • Oscillopsia: subjective experience of motion of stationary objects, associated with VOR deficit or vestibular hypofunction

  • Evaluation

    • Identification of symptoms

    • Duration and circumstances of symptoms

    • Examination of eye movements

    • Observation for Nystagmus

    • Head Impulse Test

    • Head-Shaking Induced Nystagmus Test

    • Positional Testing

Medical Information about Cranial Nerve Injuries

Page 15

Examination of Eye Movements

  • Critical for defining and localizing vestibular pathology

  • Key tests include:

    • Observation for nystagmus

    • Head Impulse Test (examination of the VOR at high acceleration)

    • Head-Shaking Induced Nystagmus (HSN) test

    • Positional testing

Observation for Nystagmus

  • Two forms of nystagmus: jerk nystagmus and pendular nystagmus

  • Jerk nystagmus:

    • Consists of slow and fast components

    • Direction of jerk nystagmus is the direction of the fast phase

  • Pendular nystagmus:

    • Sinusoidal oscillation with slow phase in both directions and no corrective saccade

  • Nystagmus due to a vestibular lesion:

    • Slow and fast component

    • Direction of the nystagmus named by the direction of the fast component

  • Peripheral vestibular lesion:

    • Slow component due to relative excitation of one side of the vestibular system

    • Fast component generated from the parapontine reticular formation in the brain stem

  • Vestibular nystagmus can be suppressed in light and when visually fixating on a target

Head-Shaking Induced Nystagmus (HSN) Test

  • Used to examine semicircular canal function

  • Patient fixates on a near target while their head is manually rotated in an unpredictable direction

  • In a patient with a loss of vestibular function, the eyes will not move as quickly as the head rotation and will move off the target

  • Corrective saccade is made to reposition the eyes on the target

Page 16

Positional Testing

  • Used to identify whether otoconia have been displaced into the SCC, causing benign paroxysmal positional vertigo (BPPV)

  • Dix-Hallpike test is the most common positional test used to examine for BPPV

  • Direction and duration of the resultant nystagmus can help determine the type of lesion

Vestibular System Dysfunction

  • Peripheral Pathology:

    • Mechanical (Benign Paroxysmal Postural Vertigo)

    • Most common cause of vertigo is BPPV

    • BPPV occurs via cupulolithiasis and canalithiasis mechanisms

  • Central Nervous System Pathology:

    • Cerebrovascular insults, TBI, MS

Page 17

Ocular Tilt Reaction

  • OTR for unilateral central vestibular pathology:

    1. Head tilting

    2. Skew deviation of the eyes

    3. Torsion of the eye

Intervention for BPPV

  • Canalith repositioning maneuver

  • Liberatory (Semont) maneuver

  • Brandt-Daroff exercises

Intervention for Unilateral Vestibular Hypofunction

  • Gaze Stability Exercises

  • Postural Stability Exercises

  • Habituation Exercises (Motion Sensitivity)

Page 18

Gaze Stability Exercises

  • Improve the VOR and other systems used for gaze stability with head motion

  • Retinal slip occurs when the image of an object moves off the fovea of the retina

Postural Stability Exercises

  • Improve balance by encouraging the development of balance strategies

  • Important to incorporate head movement into the exercises

Habituation Exercises (Motion Sensitivity)

  • Warranted when a patient with unilateral vestibular hypofunction has continual complaints of dizziness

  • Reduction in response to a repeatedly performed movement

Page 19

  • Tables: House-Brackmann Scale, Physiology and Motor Control

Medical Information about Cranial Nerve Injuries

Page 20

  • Clinical Correlation in PT Bell's Palsy, Cranial Nerve Injuries, Vestib Cond

    • Balance tests and expected results related to specific diagnosis:

      • BPPV (Benign Paroxysmal Positional Vertigo)

        • Romberg test: Negative

          • Acute: positive

          • Chronic: negative

        • Tandem Romberg test: Negative

        • Single-legged test: Negative

          • Acute: positive

          • Chronic: negative

        • Gait: Normal

          • Acute: wide-based, slow, decreased arm swing and trunk rotation

          • Compensated: normal

        • Turn head while walking: May produce slight unsteadiness

          • Acute: may not keep balance or slows balance, increased ataxia

          • Compensated: normal

      • UVH (Unilateral Vestibular Hypofunction)

        • Romberg test: Acute and chronic positive

        • Tandem Romberg test: Positive, eyes closed

        • Single-legged test: May be positive

          • Acute: positive

          • Chronic: negative

        • Gait: Acute: wide-based, slow, decreased arm swing and trunk rotation

          • Compensated: mild gait deviation

        • Turn head while walking: May not keep balance

          • Acute: may not keep balance or slows balance, increased ataxia

          • Compensated: normal

      • BVH (Bilateral Vestibular Hypofunction)

        • Romberg test: Acute and chronic positive

        • Tandem Romberg test: Positive

        • Single-legged test: May be unable to perform

        • Gait: Acute: wide-based, slow, decreased arm swing and trunk rotation

          • Compensated: normal

        • Turn head while walking: May not keep balance

          • Acute: may not keep balance or slows balance, increased ataxia

          • Compensated: normal

  • Common Symptoms Associated with Central versus Peripheral Vestibular Pathology

    • Central Vestibular Pathology

      • Ataxia often severe.

      • Abnormal smooth pursuit and abnormal saccadic eye movement tests.

      • SX (symptoms) usually do not include hearing loss; if so, it is often sudden and permanent fullness in ears, tinnitus.

      • SX might include diplopia, altered consciousness, lateropulsion.

      • SX of acute vertigo not usually suppressed by visual fixation.

      • Pendular nystagmus (eyes oscillate at equal speeds).

    • Peripheral Vestibular Pathology

      • Ataxia mild.

      • Smooth pursuit and saccades usually normal; positional testing may reproduce nystagmus.

      • SX may include hearing loss (insidious-may recover), sudden and permanent fullness in ears, tinnitus.

      • SX of acute vertigo usually suppressed by visual fixation.

      • Nystagmus will incorporate slow and fast phases (jerk nystagmus).

      • Pure persistent vertical nystagmus persists regardless of positional testing (persistent downbeat nystagmus in Hallpike-Dix test may indicate anterior canal BPPV).

Page 21

  • Postural Stability Exercises

    • Intervention for Bilateral Vestibular Hypofunction

    • Bell's Palsy, Cranial Nerve Injuries, Vestib Cond