Neuromuscular Disorders

Neuromuscular Disorders of the Hands

Neuromuscular Disorders 1CLINICAL ASSESSMENT History

Age is important. The orthopaedic surgeon deals mainly with the residual effects of neurological disease, and these may require diagnosis and treatment throughout life.

Muscle weakness. The type of weakness, its distribution and rate of onset are important clues to diagnosis.2Numbness and paraesthesiae may be the main complaints. It is important to establish their distribution as this will often localize the lesion.

Deformity: common complaint in long-standing disorders.

Other features such as headache, dizziness, loss of balance, change in visual, acuity of hearing, disorder of speech, and loss of bladder or bowel control.

EXAMINATIONInclude a complete neurological assessmentParticular attention to:mental state, natural posture, gait, sense of balance, involuntary movements,the various mode of sensibility and autonomic functions such as sphincter control, peripheral blood flow and sweating.muscle wasting, muscle tone & power, reflexes, skin changes, Dermatomes supplied by the spinal nerve roots

Some effects of neurological disordersThese patients, all of whom had polio, illustrate some of the effects of paralysis: deformity, wasting, and shortening.

The BackExamine: skin change, local deformities (e.g. kyphos), and mobility.Grading Muscle Power0 : total paralysis1 : barely detectable contracture2 : not enough power to act against gravity3 : strong enough to act against gravity4 : still stronger but less than normal5 : full power

In assessment it is important to examine not only individual mucles but also functional groups.DeformityA major problem in long-standing disorders.Arises when 1 group of muscles is too weak to balance the pull of antagonists (unbalanced paralysis).When all muscles groups are equally weak (balanced paralysis) the joint simply assumes the position imposed on it by gravity. Paralysis arising in childhood seriously affect bone growth:The bone is both thinner and shorterModeling is defectiveThe bone ends may appear dysplasticThere may be loss of joint congruityGait & PostureWatch the patient walkSpastic gait:stiff and jerky, often with the feet in equinus, the knees somewhat flexed andthe hips adducted (scissoring).Dystonia abnormal posturing of any part of the body, often aggravated when the patient concentrates on movement.High-stepping gait : the legs are lifted unnecessarily high off the ground, signifies either a problem with proprioception and balance or bilateral foot drop.

Drop-foot gait :due to peripheral neuropathy or injury of the nerves supplying the dorsiflexors of the ankle.During the swing phase, the foot falls into equinus (drops) and if it were not lifted higher than usual the toes would drag along the ground.Waddling gait:the trunk is thrown from side to side with each stepmay be due to dislocation of the hip or to weakness of the abductor muscles.

AtaxiaProduces a more obvious and irregular loss of balanceBroad-based gait, uncontrollable staggeringImaging StudiesPlain x-ray of the skull and/or spine are routine for all disorders of CNS.Further study: myelography, CT or MRI.Imaging of the spine aimed at demonstrating compression of the spinal cord or nerve roots.Fractures and dislocations plain x-ray. But a CT scan will reveal the exact relationship of bone fragments to nerve structures.Prolapsed intervertebral disc diagnosed on clinical examination. Myelography, CT, MRI exact lesion site.

Narrowing of the spinal canal CT.

Destructive lesions of the bones plain x-ray. CT, MRI and myelography are helpful.The pedicles have been destroyed by tumourNeurofibromaDegenerations of the facet joints with encroachment on the intervertebral foramina & spinal canal

ElectrodiagnosisEMG (electromyography) records the motor response to nerve stimuli.Decide whether muscle weakness is due to nerve or muscle disorder

Nerve conduction studies establish the site of compression in peripheral nerve entrapment.Other Special InvestigationsBlood tests (cell counts, ESR, serology, blood sugar, muscle enzymes)CSF (cerebrospinal fluid) examinationSpecialized tests for vision, hearing, speech and mental capacity.Muscle biopsyPrinciples of Orthopaedic Treatment of Neurological DisordersPrevention of musculoskeletal deformity Passive movement at involved joint, several minutes each dayCorrection of existing musculoskeletal deformity Passive stretching or Surgical proceduresImprovement of muscle balance Muscle & tendon transfersImprovement of function Functional bracesImprovement of gait or appearance Surgical lengthening or surgical shorteningRehabilitationTreatment of the Principal Deformities of the LimbsDEFORMITYSPLINTAGESURGERYFootEquinusSpring-loaded dorsoflexionLengthen tendo AchillesEquinovarusBracing in eversion and dorsoflexionLengthen tendo Achilles and transfer bilateral half of tibialis anterior to cuboidKneeFlexionLong caliperHamstring releaseHipAdduction-Obturator neurotectomyAdductor muscle releaseShoulderAdduction-Subscapularis releaseElbowFlexion-Release elbow flexorsWristFlexionWrist splintLengthen or release wrist flexorsDISORDERS OF THE BRAINCerebral PalsyVarious types and degrees of nonprogressive brain disorders, develop soon after birthMental disabilityIncidence is relatively common, 6 affected child among 100.000 population each yearEtiology: Prenatal (Genetics, Congenital cerebral malformations, prenatal intracranial hemorhage.)Postnatal (Rh incompatibility, kern incterus, cerebral infections, head injury

Pathogenesis & PathologyBrain lesion is not progressiveManifestations of brain lesion determined by the area involved :Spastic type : corticospinal system lesion in cerebral motor cortex, 65%Athetoid type : extrapyramidal system lesion in basal ganglia, 20%Ataxic type : cerebellar and brain stem lesion, 5%3 additional type: tremor, rigidity, atoniaTopographic distribution:Hemiplegia the commonestPalsy of the upper and lower limbs on one side of the bodyDiplegiaAffects mainly the lower limbsTotal body involvementGeneral disorder affecting all 4 limbs, the trunk, neck, and face.Other terms such as monoplegia, triplegia, and tetraplegiaClinical Features and Diagnosis:

Retarded motor developmentMotor and sensory deficitsShort attention spanVarious types of CP are not obvious during the early months of postnatal development.Spastic TypeParalysis of patterns of voluntary movementIncreased muscle tone (hypertonicity, spasticity, increased deep tendon reflex, and clonus)Spastic gaitDifficult in learning to speak clearlyDysphagia (spastic paralysis of the muscles of swallowing)

Athetoid typeInvoluntary, uncontrollable movements (mobile spasms) in the muscle groups of the face and all 4 limbs.Athetotic muscles twisting, writhing contortions in the limbs, meaningless grimaces in the face, difficulty with speech and swallowing.Absent during sleep.

Ataxic typeRelative lack of equilibrium.The gait is unsteady; frequently appears about to fall, although this is usually prevented by using the arms to maintain balance.

Scissors stanceFlexion deformity of hips and knees with equinus of the feetCharacteristic facial expression and limb deformities

Treatment

Requires combined skills of the family physician, rehabilitation physician, neurologist, orthopaedic surgeon, neurosurgeon, psychologist, physical, occupational and speech therapist, medical social worker, and teacher.Therapeutic drugsNo type of drug can affect the brain lesionInjection of Botulinum A-toxin for very young children with spastic diplegia or quadriplegia and dynamic deformities of the lower limbs but no structural contracture

Physical and Occupational TherapyTo encourage muscle relaxation, improve muscle coordination and develop voluntary muscle controlSimple activity standing, walking, eating, dressing painstaking and repetitive trainingDaily passive stretching of spastic muscleSpeech TherapyProlonged therapy can be improved to the point of being reasonably intelligible.

Orthopaedic AppliancesRemovable splints prevent deformityBraces for lower limbs CrutchesCorrect deformities and improve function by physical therapy and operations.

Surgical ManipulationCorrection of fixed deformities by stretching muscle contractures under general anesthesiaMaintained by removable splints

Orthopaedic OperationsNot indicated until the child has at least develop kneeling balance.Tendon lengthening, tendon transfer, arthrodesis.Neurosurgical Operations Selective dorsal rhizotomyDecrease the stimulating inputs from the muscle spindles in the lower limbs that arrive in the spinal cord via afferent fibres in the dorsal nerve roots.Troublesome pattern of athetoid movement can be diminished by selective neurotectomy.Ataxic type not amenable to surgical treatment.PrognosisRepeated mental and physical assessment over many months is necessary to establish a realistic prognosis.In general: hemiplegics 70% have normal intelligence and all will walkSpastic diplegics 60% have IQ above 80 and 75% will walkQuadriplegics 90% have an intellectual disability and only 25% will walk.

Cerebrovascular Disease & HemiplegiaThe most catastrophic complication of the various types of cerebrovascular disease STROKE; caused by hemorrhage, thrombosis, or embolism.Treatment psychotherapy, physical and occupational therapy, light braces, selective nerve blocks to relieve spasticity and, occasionally, tendon transfers to restore muscle balance and improve function.

DISORDERS AND INJURIESOF THE SPINAL CORDSyringomyeliaSlow but progressive enlargement of an abnormal cavity within the spinal cord, most commonly in the cervical region.More than half of patients associated with prolapse of the cerebellar tonsils through the foramen magnum of the skull (the Chiari malformation).Dissociated sensory loss loss of pain and temperature sensation but preservation of light touch, vibration and position sense.Diagnostic imaging MRINeurosurgical drainage of the syrinx reduce the fluid pressure on the spinal cord.Syringomyelia with a Chiari malformation neurosurgical decompression of the foramen magnum.Poliomyelitis Viral infectionAffects the motor cells (anterior horn cells) of the spinal cordProducing permanent paralysisClinical features:Prodromal phase (2 days): non spesific systemic symptoms common to many viral infectionsAcute phase; fever, severe headache, neck rigidity, painful spasm, tenderness in affected muscles. CSF lymphocytes >>>2 months flaccid paralysisRecovery phase (up to 2 years) gradual recovery of any transient paralysis. 1/3 of the patients will make a complete recovery.

Shortening and wasting of the left leg, with equinus of the ankleParalytic scoliosisThis boy is trying to abduct both arms but the right deltoid and supraspinatus are paralyzed

Treatment:Acute phaseKept in bed, treated symptomaticallyRemovable splintThe joint of paralyzed limb are gently put through a full range of motion for several minutes each day (after muscle spasm has subsided)Recovery phaseActive exercisesSuitable bracesOperative treatment is deferred until there is no further hope of muscle recovery.The most efficacious surgical operations:Tendon lengtheningTendon transferTenodesisOsteotomy near a joint ArthrodesisLeg-length equalization

Cervical myelopathy caused by spondylosis is a capricious condition with a lack of correlation between the range of symptoms (headache, giddiness, drop attacks, numb or 'useless hands', muscle wasting, etc.), their severity, and the radiological severity of the spondylosis. 46In many patients there are a number of symptoms but few neurological signs. In a few patients, there may be a paraparesis or segmental muscle wasting, as in this patient with spinal subluxation at the level of C6/7

47Some patients (usually the elderly) with normal power in the hands complain of a loss of feeling and of difficulty in performing daily activities, such as dressing, shaving and using toilet paper. Their hands are strong and show no muscle wasting but, when the patient's eyes are closed, the fingers tend to wander ('pseudoathetosis' or sensory wandering) and the patient is unable to maintain a stationary position of the affected arm.48

49The sensory loss is usually confined to posture and vibration; the objects placed in the patient's hand (with the eyes closed) cannot be identified by touch (astereognosis).The claw hand caused by an injury to the ulnar nerve differs from that described already in that the clawing predominantly affects the fourth and fifth fingers of the hand, which also show a slight degree of abduction.50

This deformity is a result of paralysis of the interossei and the medial two lumbricals, which, in combination, flex the fingers at the metacarpophalangeal joints with the distal joints extended.51The hypothenar eminence is flattened (pict 1) with loss of the ulnar contour, which can be readily revealed by asking the patient to fold their hands in the manner of the Indian greeting (pict 2).

1252There is guttering of the spaces between the metacarpals on the dorsum of the handcaused by paralysis of the interossei, which are supplied by the ulnar nerve. The palm is hollowed out and there is a zone of cutaneous anaesthesia along the ulnar border of the hand, the fifth finger and the inner half of the fourth finger.

53The patient with an ulnar nerve palsy is unable to flex the little finger at the interphalangeal joints (using the short flexor), adduct (using the palmar interossei) or abduct (using the dorsal interossei) the fingers in the affected hand. The thumb is also affected because of paralysis of the adductor and short flexor muscles. The weakness of these two muscles can be revealed by the journal test of Froment54

The journal test of Froment: the patient has to pinch to hold on to the paper55The corresponding elbow must be examined in every patient with an ulnar nerve palsy for any evidence of injury, fracture, dislocation, scar or arthritis.A patient with osteoarthrosis of the elbow joint will be unable to touch his head with the hand, while keeping his arm straight at the shoulder joint

56The ulnar nerve may be involved in Hansen's disease (leprosy) producing a typical claw hand.

The thickened ulnar nerve may be palpable in the ulnar groove at the elbow joint. The nerve may also be injured by penetrating wounds, and as a late sequel to callus or scar formation at any point along its course. Certain occupations such as roofing, carpentry and bricklaying are associated with osteoarthrosis of the elbow and injuries to the nerve in its shallow olecranon groove.57Carpal Tunnel Syndrome the commonest cause of a median nerve palsycaused by compression of the nerve, as it traverses the tunnel under the thick and inelastic transverse carpal ligament. Flattening of the thenar eminence is the hallmark of a median nerve palsy.

58Scalding of the index and middle fingers resulting from loss of sensory perception is seen rarely today.

The diagnosis is made early on the strength of a good history (pain and numbness over the median nerve distribution, which is worse at night, often relieved by rubbing and hanging the arm out of bed) and by functional evaluation of the thumb and the outer two fingers (weak abductor pollicis and opponens pollicis).59This condition is usually seen in middle-aged, obese females. It may be associated with pregnancy, myxoedema, acromegaly, rheumatoid arthritis, tophaceous gout and primary amyloidosis.

The extended thumb and index finger, hollowing of the thenar eminence with the thumb on a level with the fingers, and the flat, even appearance of the palm, produce the monkey (or simian) hand.60In complete palsy of the median nerve in the forearm, the appearance of the hand and the forearm is characteristically flat on the flexor aspect, with slight ulnar deviation and loss of pulp in the affected fingers. The patient can bend the middle finger but not the terminal phalanx of the thumb and index finger, which requires the use of flexor digitorum profundus & flexorpollicis longus.

61Abduction of the thumb is weak and can be easily overcome from paralysis of the abductor pollicis brevis.

62Inability to make a complete fist by flexing the terminal phalanges of the thumb and index finger is caused by an injury to the anterior interosseous nerve, which arises from the median nerve in the forearm. This nerve supplies the radial half of the flexor digitorum profundus and flexor pollicis longus.

63Even when the wrist is passively held straight, the fingers remain flexed at the metacarpophalangeal joints owing to paralysis of the long extensors

Wrist drop, or a complete inability to extend the hand and fingers, is a cardinal feature of paralysis of the radial nerve. 64The patient is, however, able to straighten the interphalangeal joints since these movements are affected by the lumbricals and interossei (the ulnar nerve).

65DISORDERS OF MUSCLEMajority neurogenic rather than myogenic.Muscular DystrophiesA group of genetically determined disorders of muscle (primary myopathies).Progressive muscle degeneration and weakness.Types:DMD (Duchenne muscular dystrophy)BMD (Becker muscular dystrophy)Limb girdle muscular dystrophyFacioscapulohumeral muscular dystrophyDuchenne TypePseudohypertrophic muscular dystrophySex-linked recessive traitAfflicts males onlyAbsence of dystrophin (a protein normally present in the sarcolemma of muscle cells)Tire easily and cannot keep up with his playmates.Symmetrical weakness of the pelvic muscles difficulty in climbing stairs and standing up from a sitting or lying position.Gowers sign in muscular dystrophy

Pseudohypertrophy in the calf muscles, the increased bulk of muscle being due to excessive fibrous tissue and fat.The muscle and shoulder girdle become weak.Deformities secondary to contracture: progressive paralytic scoliosis.Progression: relentless.Lab elevation of certain cellular enzymes (creatinine phosphokinase and aldolase alanine transaminase) that probably arise from affected muscles.Becker Muscular DystrophySex-linked recessive trait.Altered dystrophin.Appears at later age, less severe and more slowly progressive than DMD.Treatment is similar to DMD.Treatment of MDNo spesific cureMultidisciplinaryPrednison can improve strength and functionMyoblast transfer has not been proven to be beneficialActive exerciseDietary supervision reduce obesityLight braces, orthopaedic operationsEND