Neuromuscular: Progressive, Peripheral and Vestibular Disorders

Progressive neurologic disease asks the physical therapist not only how to restore function, but how to protect it, pace it and plan for the losses ahead. The exam leans on these conditions because the right answer depends on the diagnosis: avoiding overwork weakness in Guillain Barre syndrome, cooling the patient with multiple sclerosis, timing exercise to the levodopa dose, or choosing the maneuver for the involved canal.

Section 1Parkinson disease and movement disorders

What goes wrong in the basal ganglia

Parkinson disease (PD) is a progressive neurodegenerative disorder in which dopamine producing neurons of the substantia nigra pars compacta die, and the surviving neurons contain clumps of alpha synuclein called Lewy bodies. By the time motor signs appear, more than half the nigral neurons are often lost. Dopamine normally facilitates the direct pathway of the basal ganglia and inhibits the indirect pathway, which brakes movement. Without it, the internal globus pallidus overinhibits the thalamus, so movement becomes small (hypokinesia), slow (bradykinesia), hard to start (akinesia), and shrinks as it is repeated.

Typical onset is after age 60, men are affected slightly more often than women, and signs begin on one side. Nonmotor features often come first: loss of smell, constipation, REM sleep behavior disorder, depression, orthostatic hypotension, fatigue and, later, dementia.

The cardinal signs

The four classic motor signs are remembered as TRAP:

• Tremor at rest: a 4 to 6 Hz "pill rolling" tremor of the thumb and fingers that is present at rest, lessens with voluntary movement, worsens with stress, and disappears in sleep. About a quarter of patients never develop it.
• Rigidity: increased resistance to passive movement that is the same in both directions and does not depend on velocity. Smooth resistance is lead pipe rigidity; when tremor is superimposed the resistance catches and releases in a ratchet pattern called cogwheel rigidity. This is the key contrast with spasticity, which is velocity dependent and usually greater in one direction.
• Akinesia and bradykinesia: poverty and slowness of movement, including reduced blinking, a masked face (hypomimia), soft speech (hypophonia), small handwriting (micrographia), reduced arm swing and difficulty turning in bed.
• Postural instability: impaired righting and protective reactions, especially backward (retropulsion). It appears later in the disease, responds poorly to levodopa, and is a major cause of falls.

Posture becomes flexed, extension and rotation range are lost, and kyphosis lowers vital capacity. Dysphagia raises the risk of aspiration pneumonia, a leading cause of death in late PD.

Parkinsonian gait and freezing

The gait is slow with a short step length, reduced foot clearance, decreased hip and knee excursion, reduced or absent arm swing, a narrow base and en bloc turning (the head, trunk and pelvis turn as one unit, with many small steps). Festination is an involuntary acceleration of progressively shorter steps as the center of mass falls ahead of the feet; the patient appears to chase the center of mass. Freezing of gait is a brief, episodic inability to step despite the intention to walk, as if the feet were glued to the floor. It is provoked by starting to walk, turning, passing through doorways or narrow spaces, approaching a destination, dual tasking and stress, and it is strongly associated with falls.

Medications and timing therapy

Carbidopa levodopa is the most effective drug; carbidopa blocks peripheral conversion of levodopa so more reaches the brain and nausea is reduced. Dopamine agonists, MAO B inhibitors and COMT inhibitors supplement it. After several years many patients develop motor fluctuations: a wearing off of benefit before the next dose, unpredictable on off switching, and peak dose dyskinesias, which are involuntary writhing or choreiform movements caused by too much dopamine effect, not by the disease itself. Watch for orthostatic hypotension, hallucinations and confusion.

Schedule therapy during the on period, typically about 45 to 60 minutes after a dose, when mobility is best and learning is easiest. Record the time of the last dose; a patient who varies from week to week may simply arrive at a different point in the dose cycle.

Examination and outcome measures

The disease specific scale is the Movement Disorder Society Unified Parkinson Disease Rating Scale (MDS-UPDRS), whose part III is the motor examination. Recommended measures include the Mini BESTest, Berg Balance Scale, Timed Up and Go (with a dual task), Five Times Sit to Stand, gait speed and the Six Minute Walk Test. In the pull test (shoulders pulled briskly backward), more than two backward steps or needing to be caught is abnormal. Always measure orthostatic blood pressure: a drop of 20 mmHg systolic or 10 mmHg diastolic within three minutes of standing defines orthostatic hypotension.

Intervention principles

Exercise improves fitness, gait, balance, strength and quality of life at every stage. The PD clinical practice guideline strongly supports aerobic exercise (including moderate to high intensity, roughly 60 to 85 percent of heart rate reserve), resistance training, balance training, and external cueing for gait.

• Amplitude based training (for example the LSVT BIG approach and its speech counterpart LSVT LOUD) uses high effort, large amplitude, whole body movements repeated intensively (classically four sessions a week for four weeks) with recalibration of the patient's sense of normal size. Patients perceive their small movements as normal; the training teaches them that "big" feels exaggerated but looks normal.
• External cueing bypasses the defective internal timing of the basal ganglia by using cortical and cerebellar circuits. Visual cues include transverse lines or tape on the floor at the desired step length and laser lines projected from a walker or shoe. Auditory cues include a metronome or music set near or slightly above the comfortable cadence. Attentional cues ask the patient to think "big step" or to step over an imagined line. Somatosensory cues include rhythmic tapping.
• Freezing strategies: stop, stand tall, shift weight side to side, then step big over a real or imagined line; turn in a wide arc rather than pivoting; count steps aloud; avoid carrying objects while walking through doorways.
• Flexibility and posture: spinal extension and rotation, hip extension, and pectoral, hamstring and hip flexor length.
• Treadmill and dual task training once single task walking is safe; movement strategy training breaks complex tasks into conscious steps in advanced disease.

Other movement disorders

Section 2Multiple sclerosis, ALS and other progressive diseases

Multiple sclerosis: mechanism and presentation

Multiple sclerosis (MS) is an immune mediated inflammatory disease of the central nervous system in which T cells and B cells attack myelin and oligodendrocytes, leaving plaques of demyelination and, over time, axonal loss. Because only the CNS is affected, peripheral nerves and the neuromuscular junction are spared. Lesions are scattered in time and space (periventricular white matter, optic nerves, brainstem, cerebellum, cervical cord). Onset is usually at 20 to 40 years, women are affected two to three times as often, and risk rises with distance from the equator, low vitamin D, smoking and prior Epstein Barr virus infection.

Symptoms include:

• Fatigue, the most common and often most disabling symptom, frequently worse in the afternoon.
• Sensory changes: numbness, tingling, a band like feeling around the trunk, and Lhermitte sign (an electric sensation down the spine and limbs with neck flexion, a sign of cervical cord involvement).
• Optic neuritis (painful unilateral vision loss, often the first event) and internuclear ophthalmoplegia.
• Motor: weakness and spasticity with upper motor neuron signs, typically in the legs.
• Cerebellar: ataxia, intention tremor, dysmetria, scanning speech and nystagmus (the classic Charcot triad is nystagmus, intention tremor and scanning speech).
• Heat sensitivity: the Uhthoff phenomenon is a temporary worsening of symptoms when core temperature rises (exercise, hot weather, a hot bath, fever). Heat slows conduction in demyelinated axons; it resolves with cooling.

Clinical courses

The older label progressive relapsing MS is now folded into primary progressive disease described as active. Disability is commonly graded with the Expanded Disability Status Scale (EDSS, 0 to 10 in half steps). Anchor points worth knowing: 4.0 means fully ambulatory without aid for about 500 meters; 6.0 means a unilateral assistive device is needed to walk about 100 meters; 6.5 means bilateral assistance; 7.0 means essentially restricted to a wheelchair; 10 is death due to MS.

Examination and intervention in MS

Useful measures include the Timed 25 Foot Walk, the Six Minute Walk Test (speed falling in later minutes shows motor fatigability), the 12 item MS Walking Scale, the Modified Fatigue Impact Scale, the Berg Balance Scale and the Modified Ashworth Scale.

Exercise is safe and beneficial in MS and does not trigger relapses. Current guidance supports moderate intensity aerobic exercise (for example about 30 minutes at moderate intensity two or three times a week, built up gradually) and resistance training two or three times a week, plus balance training, flexibility and task specific gait training. Practical precautions:

• Prevent overheating: exercise in a cool, air conditioned room, early in the day, with fans, cooling vests, cold drinks and pre cooling. Aquatic therapy should use cool water, generally below about 84 to 85 degrees Fahrenheit (about 29 degrees Celsius); avoid hot tubs and warm therapy pools.
• Use interval training and rest breaks; schedule sessions in the morning when fatigue is lowest.
• Do not exercise vigorously during an acute relapse, especially while receiving high dose corticosteroids; shift to positioning, gentle ROM and maintaining function, then resume a graded program as the relapse settles.
• Manage spasticity with daily stretching and positioning; leg spasticity sometimes aids standing, so treat it when it interferes.

Energy conservation is taught explicitly, often as the four Ps: plan the day and week, pace activities with rest before fatigue sets in, prioritize what truly matters, and position the body and the environment for efficiency (sitting to dress, keeping items within reach).

Amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis (ALS) is a progressive degeneration of both upper motor neurons (motor cortex and corticospinal tracts) and lower motor neurons (anterior horn cells and motor cranial nerve nuclei). About 10 percent of cases are familial; onset is usually in the late 50s to 60s. The patient shows a mixed picture: weakness, atrophy, fasciculations and cramps (lower motor neuron) together with spasticity, hyperreflexia and a Babinski sign (upper motor neuron), often in the same limb. Onset is usually asymmetric in a hand or foot; bulbar onset (dysarthria, dysphagia, tongue fasciculations) carries a worse prognosis.

ALS characteristically spares sensation, eye movements, and bowel and bladder control, and most patients keep their cognition, although a minority develop frontotemporal dementia. Median survival is about three to five years from symptom onset, and death is usually from respiratory failure. Riluzole and edaravone modestly slow progression.

Physical therapy goals follow the stage and the prognosis:

• Early (mild weakness): moderate, submaximal aerobic and resistance exercise without exhaustion, only for muscles with at least antigravity strength. Weaker muscles may suffer overwork; fatigue lasting over about 30 minutes, or weakness the next day, means the dose was too high.
• Middle (some limbs severely weak): ROM and stretching, energy conservation, orthoses (ankle foot orthosis, cervical collar, wrist hand orthoses) and assistive devices.
• Late (dependent): positioning, skin protection, airway clearance, caregiver training, hospital bed, lift, and a tilt in space power wheelchair with head support.

Anticipate equipment: start the power wheelchair evaluation months before it is needed, with controls adaptable to future hand weakness. Monitor respiratory function: forced vital capacity below about 50 percent of predicted, orthopnea, morning headaches or disturbed sleep signal the need to discuss noninvasive ventilation. Teach assisted cough and breathing strategies.

Section 3Peripheral neuropathies and neuromuscular disease

Localizing weakness along the motor unit

A motor unit is one lower motor neuron and all the muscle fibers it supplies. Disease can strike the cell body (anterior horn cell), the axon or its myelin (peripheral nerve), the synapse (neuromuscular junction), or the muscle fiber itself. Each site leaves a recognizable fingerprint, and identifying the site is often the first step to the right answer.

Guillain Barre syndrome

Guillain Barre syndrome (GBS) is an acute immune mediated polyneuropathy, most often the demyelinating form (acute inflammatory demyelinating polyradiculoneuropathy). About two thirds of patients report a respiratory or gastrointestinal infection one to four weeks earlier; Campylobacter jejuni is the classic trigger.

• Presentation: rapidly progressive, relatively symmetric weakness that usually starts in the legs and ascends, with distal paresthesias, back or limb pain, and areflexia. Cranial nerves (especially bilateral facial weakness) and respiratory muscles may be involved.
• Autonomic instability: fluctuating blood pressure, arrhythmias, tachycardia or bradycardia, and orthostatic hypotension.
• Course: weakness peaks within four weeks, plateaus, then recovers over months in a descending order. Most patients walk independently within a year; about 20 percent keep significant disability.
• Diagnosis: high cerebrospinal fluid protein with a normal cell count (albuminocytologic dissociation) and slowed nerve conduction.
• Treatment: intravenous immunoglobulin or plasma exchange, which shorten the course when given early. Corticosteroids are not effective.

About a quarter of patients need mechanical ventilation. Monitor vital capacity: a falling value (below about 20 mL/kg is a commonly cited threshold for intubation), weak cough, and difficulty counting to 20 in one breath are warnings. In the acute phase, the therapist focuses on positioning, gentle passive and active assisted ROM, splinting to prevent contracture (for example resting ankle splints), pressure injury prevention, chest physical therapy and airway clearance, and gradual tilt to upright with blood pressure monitoring.

In recovery, exercise must avoid overwork of reinnervating muscles. Use low intensity, low repetition, frequently rested exercise and progress slowly, watching for increased weakness, cramping or prolonged fatigue in the following 24 hours. Chronic inflammatory demyelinating polyneuropathy (CIDP) progresses for more than eight weeks and, unlike GBS, responds to corticosteroids.

Diabetic and other polyneuropathies

Diabetic peripheral neuropathy is the most common neuropathy in developed countries. The usual form is a distal symmetric sensorimotor polyneuropathy that begins in the toes and spreads proximally in a stocking and glove distribution, because the longest axons fail first. Small fiber loss causes burning pain; large fiber loss causes loss of vibration and proprioception, reduced ankle reflexes and a positive Romberg test. Intrinsic foot weakness produces claw toes. Autonomic neuropathy causes dry, cracked skin, orthostatic hypotension, resting tachycardia and a blunted heart rate response to exercise.

The key screening test is the 5.07 (10 gram) Semmes Weinstein monofilament: inability to feel it at tested plantar sites indicates loss of protective sensation and a high risk of ulceration. Combine it with vibration testing (128 Hz tuning fork), ankle reflexes and a foot inspection. Management includes daily foot inspection, depth shoes and insoles, never walking barefoot, balance training, and exercise with glucose monitoring. Weight bearing exercise is acceptable with proper footwear if there is no active ulcer; choose non weight bearing exercise (cycling, swimming) when an ulcer or acute Charcot foot is present. Because autonomic neuropathy blunts the heart rate response, use RPE rather than target heart rate.

A warm, red, swollen foot with intact skin in a person with neuropathy should be treated as an acute Charcot neuroarthropathy until proven otherwise; it needs immediate offloading (total contact cast) and referral, not exercise.

Post polio syndrome

Poliomyelitis destroys anterior horn cells; surviving neurons sprout to adopt orphaned muscle fibers, creating giant motor units. Decades later (typically 15 or more years after the acute illness), these overextended units begin to fail. Post polio syndrome presents with new weakness, often in previously affected muscles, unusual fatigue, muscle and joint pain, cold intolerance, and sometimes new breathing or swallowing problems. Management centers on pacing: nonfatiguing, submaximal exercise with frequent rests, energy conservation, weight control, and lightweight orthoses and devices to unload overused muscles.

Myasthenia gravis and Lambert Eaton syndrome

Myasthenia gravis (MG) is an autoimmune disease in which antibodies attack the postsynaptic acetylcholine receptors at the neuromuscular junction (some patients have antibodies against MuSK instead). Fewer functional receptors means each nerve impulse has less safety margin, so strength fades with repeated use. Hallmarks are fatigable weakness that worsens through the day and with activity and improves with rest, ptosis and diplopia (ocular muscles are involved in most patients and are often first), bulbar weakness (dysarthria, dysphagia, a nasal voice, difficulty chewing), and proximal limb and neck extensor weakness. Sensation and reflexes are normal. Thymus abnormalities are common, and thymectomy is part of treatment.

Treatment includes acetylcholinesterase inhibitors (pyridostigmine), corticosteroids and other immunosuppressants, and IVIG or plasma exchange for crises. Two emergencies matter:

• Myasthenic crisis: respiratory and bulbar failure, often triggered by infection, surgery or drugs such as aminoglycosides.
• Cholinergic crisis: weakness from excess anticholinesterase drug, with salivation, sweating, diarrhea, small pupils and bradycardia.

For therapy, schedule exercise when the medication is at peak effect (commonly about one to two hours after a pyridostigmine dose) and when fatigue is low (often the morning). Use short bouts with rest, avoid exhaustion and heat, and monitor breathing and swallowing; moderate exercise is safe in stable MG.

Lambert Eaton myasthenic syndrome is an autoimmune attack on presynaptic voltage gated calcium channels, so less acetylcholine is released. Strength and reflexes briefly improve with repeated effort (facilitation), the weakness is proximal and in the legs, autonomic symptoms such as dry mouth are common, and about half the cases are associated with small cell lung cancer. A patient with new proximal weakness, dry mouth and a smoking history needs referral to look for a tumor.

Muscular dystrophies

In Duchenne muscular dystrophy, the absence of dystrophin leaves the membrane fragile, so contraction, especially eccentric, tears fibers that are replaced by fat and connective tissue. Creatine kinase is markedly elevated. The Gowers sign (climbing up the thighs to stand) reflects hip extensor weakness. Plan ahead:

• Prevent contractures: daily stretching of heel cords, hamstrings, hip flexors and iliotibial bands, night resting ankle foot orthoses, and standing programs.
• Exercise: submaximal swimming, cycling and play; avoid eccentric work and exhaustion. Muscle pain or dark urine after exercise signals overwork.
• Mobility, spine and breathing: knee ankle foot orthoses may prolong standing; then a power wheelchair with postural support. Monitor scoliosis, teach assisted cough, and support cardiac and vital capacity monitoring.

Section 4Vestibular disorders

The vestibular system in brief

Each inner ear contains three semicircular canals (anterior, posterior and horizontal) that sense angular acceleration, and two otolith organs (utricle and saccule) that sense linear acceleration and head tilt relative to gravity. The utricle contains calcium carbonate crystals called otoconia. The canals work in push pull pairs: turning the head right excites the right horizontal canal. Vestibular signals drive the vestibulo ocular reflex (VOR), which moves the eyes opposite to the head to keep images stable on the retina, and the vestibulospinal reflexes, which keep the body upright. A mismatch between the two sides produces vertigo (an illusion of movement) and nystagmus, a rhythmic eye movement with a slow drift and a fast corrective beat. Nystagmus is named by the direction of its fast phase.

Benign paroxysmal positional vertigo

Benign paroxysmal positional vertigo (BPPV) is the most common cause of vertigo. Otoconia dislodge from the utricle and move into a semicircular canal. In canalithiasis, the debris floats freely in the canal and drags the endolymph when the head moves into the plane of that canal, causing brief vertigo with a short latency. In cupulolithiasis, debris sticks to the cupula and makes it gravity sensitive, causing vertigo and nystagmus that persist as long as the head stays in the provoking position.

Spells of spinning vertigo last seconds and are triggered by rolling in bed, lying down or looking up; hearing and the neurologic examination are normal.

• Posterior canal BPPV is by far the most common (roughly 80 to 90 percent), because the posterior canal is the lowest part of the labyrinth when upright and supine.
• Horizontal (lateral) canal BPPV accounts for most of the rest.
• Anterior canal BPPV is rare.

Positional tests and treatment by canal

The Dix-Hallpike test examines the posterior (and anterior) canal. The patient sits long sitting on the table, the head is rotated 45 degrees toward the side being tested, and the patient is brought quickly back to supine with the neck extended about 20 degrees over the end of the table. The examiner watches the eyes for 30 to 60 seconds. Posterior canal canalithiasis produces upbeating and torsional nystagmus (top of the eye beating toward the down, affected ear) after a few seconds of latency, lasting under 60 seconds and fatiguing with repetition. The side-lying test is an alternative when neck extension is unsafe.

The supine roll test examines the horizontal canal: with the patient supine and the head flexed about 30 degrees, the head is rotated quickly about 90 degrees to each side. Horizontal canal BPPV produces horizontal nystagmus on both sides.

• Geotropic nystagmus (beating toward the ground on each side) indicates canalithiasis; the side with the stronger nystagmus and symptoms is the affected side.
• Apogeotropic nystagmus (beating away from the ground) indicates cupulolithiasis (or debris near the cupula); the side with the weaker response is usually the affected side.

The Epley canalith repositioning maneuver for right posterior canal BPPV proceeds through four positions, holding each until the nystagmus stops (generally at least 30 seconds to a minute): (1) from sitting, head turned 45 degrees to the right, recline into the right Dix-Hallpike position; (2) turn the head 90 degrees to the left so it is 45 degrees to the left, keeping the neck extended; (3) roll the body onto the left side while turning the head another 90 degrees so the face points toward the floor; (4) return to sitting with the head slightly flexed. The goal is to move the otoconia around the canal and out into the utricle. One or two maneuvers resolve the problem in most patients. Post maneuver restrictions are no longer routinely recommended; Brandt-Daroff exercises are a less effective home option.

Unilateral vestibular hypofunction

Sudden loss of function in one labyrinth or vestibular nerve creates a large imbalance between the two sides. Vestibular neuritis (inflammation of the vestibular nerve, presumed viral) presents with acute, continuous, severe vertigo lasting days, nausea and vomiting, imbalance (veering toward the affected side), and spontaneous horizontal torsional nystagmus beating away from the affected ear. The nystagmus follows Alexander's law (stronger when gazing in the direction of the fast phase) and is suppressed by visual fixation. Hearing is normal. Labyrinthitis produces the same picture plus hearing loss. Vestibular schwannoma (acoustic neuroma) causes slowly progressive one sided hearing loss, tinnitus and imbalance.

The head impulse test (head thrust) checks the VOR: the examiner turns the patient's head quickly through a small angle while the patient looks at the examiner's nose. With a normal VOR the eyes stay on target. With hypofunction, turning toward the affected side produces a corrective saccade back to the target. Also measure dynamic visual acuity (losing more than two lines with head movement is abnormal), the Dizziness Handicap Inventory and the Functional Gait Assessment.

Recovery depends on central compensation, which is driven by error signals created by moving the head. Vestibular suppressants help in the first days but slow compensation if continued. Vestibular rehabilitation uses four types of exercise:

• Adaptation (gaze stabilization): VOR times 1 (the target stays still and the head moves side to side or up and down while keeping the target in focus) and VOR times 2 (head and target move in opposite directions, a harder task). Progress speed, duration, background and posture while the target stays clear.
• Habituation: repeated, graded exposure to movements or visual environments that provoke mild symptoms, so the brain learns to reduce its response. Best for motion provoked dizziness and visual motion sensitivity.
• Substitution: using vision and somatosensation, or eye movements and saccades, to replace lost vestibular input; most important with bilateral loss.
• Balance and gait training with varied surfaces, vision and head turns.

The vestibular rehabilitation clinical practice guideline recommends gaze stabilization exercises for both acute and chronic hypofunction, with a typical minimum dose of about three times per day totaling at least 12 minutes per day in acute and subacute cases, and three to five times per day totaling about 20 minutes per day in chronic cases, plus about 20 minutes per day of balance and gait exercise. A mild, short lived increase in symptoms during exercise is expected.

Bilateral vestibular hypofunction

Loss on both sides, most often from aminoglycoside ototoxicity (gentamicin), causes oscillopsia (the visual world bounces with head movement and walking), marked imbalance, especially in the dark or on uneven ground, and a high fall risk. Vertigo is usually absent because the loss is symmetric. The head impulse test is abnormal in both directions. Rehabilitation emphasizes gaze stabilization, substitution with vision and somatosensation, balance training, night lights and often a cane. Recovery is slower and less complete, and the guideline dose is higher (about three to five times per day totaling 20 to 40 minutes per day).

Meniere disease

Meniere disease (endolymphatic hydrops) produces episodic attacks of vertigo lasting about 20 minutes to 12 hours, with fluctuating low frequency sensorineural hearing loss, tinnitus and aural fullness in the affected ear. Management is medical (low sodium diet, diuretics, procedures). Vestibular rehabilitation does not help during attacks but helps once the deficit is stable.

Central versus peripheral signs

Not every dizzy patient has an ear problem. A stroke in the brainstem or cerebellum can mimic vestibular neuritis. In a patient with acute continuous vertigo and nystagmus, the bedside HINTS examination (head impulse, nystagmus, test of skew) is more sensitive for stroke than early MRI when performed by a trained examiner. A normal head impulse in an acutely vertiginous patient is a worrying sign, because the peripheral VOR is intact and the lesion is probably central.

Section 5Cerebellar, cranial nerve and other neurologic conditions

Bell palsy

Bell palsy is an acute, idiopathic, unilateral lower motor neuron paralysis of the facial nerve (cranial nerve VII), thought to result from swelling of the nerve in the facial canal, often linked to herpes simplex reactivation, and more common in pregnancy and diabetes. Weakness develops over hours to about three days and involves the entire half of the face: the patient cannot wrinkle the forehead, close the eye completely, smile symmetrically or puff the cheek. There may also be loss of taste on the anterior two thirds of the tongue, hyperacusis (stapedius paralysis) and pain behind the ear.

The key distinction is from a central (upper motor neuron) facial palsy, such as after a stroke. The upper face receives corticobulbar input from both hemispheres, so a unilateral cortical lesion weakens only the lower face on the opposite side and spares the forehead. A lower motor neuron lesion (Bell palsy) affects the upper and lower face on the same side.

Most patients recover: about 70 percent fully, and as many as 85 percent or more show improvement within three weeks. Incomplete paralysis at onset, early improvement and younger age predict a good outcome. Oral corticosteroids started within 72 hours improve recovery; antivirals may be added in severe cases. The House Brackmann scale grades facial function from I (normal) to VI (total paralysis).

Physical therapy priorities:

• Protect the eye: incomplete closure (lagophthalmos) and reduced tearing risk corneal drying and ulceration. Teach artificial tears by day, lubricating ointment and taping or a moisture chamber at night, and sunglasses outdoors.
• Facial neuromuscular retraining: slow, small, symmetric, isolated movements in front of a mirror (mirror biofeedback), gentle massage and stretching of the affected side, and functional tasks (eating, drinking, speaking).
• Avoid mass action: forceful, maximal grimacing and gross exercises can encourage synkinesis, the unwanted linked movements (for example the eye closing when the patient smiles) that follow aberrant regeneration. Teach the patient to suppress synkinesis by moving gently and in isolation.
• Electrical stimulation is not recommended routinely for Bell palsy, because evidence is weak and there is concern that it may promote synkinesis.
• Refer if there is no improvement by three to four months, or if weakness is bilateral, progressive or joined by other cranial nerve signs.

Other cranial nerve conditions

Cerebellar ataxia

The cerebellum compares intended with actual movement and corrects errors. Damage (stroke, tumor, MS, alcohol, hereditary ataxias) produces ataxia, poorly scaled and timed movement. Cerebellar signs appear on the same side as the lesion, because the pathways cross twice. A lesion of the midline vermis produces truncal ataxia, a wide based staggering gait and titubation (head and trunk oscillation); a lesion of a cerebellar hemisphere produces limb ataxia on the same side.

Unlike sensory ataxia from dorsal column or large fiber neuropathy, cerebellar ataxia is not much worse with the eyes closed, so the Romberg test is typically negative or only mildly worse; a markedly positive Romberg points to proprioceptive loss. The Scale for the Assessment and Rating of Ataxia (SARA) is the disease specific measure.

The best supported intervention is intensive, task oriented balance and coordination training with a progressively narrower base, perturbations and varied gait. Classic approaches include Frenkel exercises (slow, repetitive, visually guided movements progressing from lying to sitting to standing) and PNF techniques such as rhythmic stabilization and alternating isometrics to build proximal stability. Light weights may damp tremor during a task but do not train lasting control. Practice must be high in volume; gains fade if training stops.

Huntington disease

Huntington disease (HD) is an autosomal dominant neurodegenerative disease caused by an expanded CAG trinucleotide repeat in the huntingtin gene on chromosome 4. Each child of an affected parent has a 50 percent risk, and longer repeats cause earlier onset. Neurons of the caudate and putamen (striatum) degenerate, reducing the brake on movement and producing excessive involuntary movement. Onset is typically between 30 and 50 years, and the disease progresses over roughly 15 to 20 years to death, often from aspiration pneumonia or complications of falls.

The classic triad is:

• Motor: chorea (brief, irregular, flowing, dance like involuntary movements), impaired voluntary movement and saccades, motor impersistence (inability to sustain a grip or tongue protrusion), dysarthria, dysphagia, and a wide based, irregular gait with sudden lurches. Late in the disease chorea often lessens and rigidity, bradykinesia and dystonia dominate. Juvenile onset (Westphal variant) presents with rigidity rather than chorea.
• Cognitive: executive dysfunction, slowed processing and eventually dementia.
• Psychiatric: depression, irritability, apathy, impulsivity, obsessive behavior and an elevated suicide risk.

Therapy moves from aerobic, strength, balance and fall prevention work early, to devices, home safety and caregiver training in the middle stage, to seating, padding, positioning and skin and respiratory care late. Chorea is treated with tetrabenazine, which can worsen depression. Keep instructions simple and routine, and screen for depression and suicidal thoughts.

Vertigo and dizziness red flags

Most dizziness is benign, but some presentations demand immediate referral. Before cervical manual therapy or positional testing, screen for cervical artery dysfunction with the familiar mnemonic of the 5 Ds and 3 Ns: dizziness, diplopia, dysarthria, dysphagia, drop attacks, and nausea, numbness, nystagmus, plus ataxia of gait.

Distinguish vertigo (a spinning or moving illusion, usually vestibular) from presyncope (lightheadedness, near fainting, usually cardiovascular or orthostatic) and disequilibrium (imbalance without a head sensation, often from neuropathy, cerebellar or multisensory loss).

Words worth knowing