Motoneuron Diseases

7/28/2019 Motoneuron Diseases

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MOTOR NEURONE DISEASES

AND OTHER

MOTOR SYSTEM DISEASE


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MND

UNKNOWN CAUSE

TRAUMA, EXCESSIVE EXERCISE, LEAD POISONING AND

MERCURY POISONING, OCCULT NEOPLASIA AND VIRUSES

HAVE ALL BEEN SPECULATIVELY LINKED WITH THE

AETIOLOGY OF MND

AFFECTING ALL RACES

YOUNG ADULT MAY BE AFFECTED, BUT MOST PATIENTS

ARE 60 YEARS OR OLDER

MALE : FEMALE = 1.5 : 1

THE AVERAGE DURATION OF SURVIVAL IS 3-4 YEARS


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CLINICAL PRESENTATION

Difficulty performing specific task:Turning a key, floppiness of a foot, a weak grip or wasting of some of the muscles of one hand

History of cramps, quivering of muscles, or

heaviness, aching and stiffness of legs

DIAGNOSIS

IS SUGGESTED BY THE PRESENCE OF

FASCICULATION OR WASTINGWITH ENHANCED REFLEXES

AND WITHOUT SENSORY SIGNS


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CHARACTERIZED BY

Progressive degeneration of

anterior horn cells

corticospinal fibers, and

motor nuclei in the medulla

Various levels of the nervous system:

bulbar, cervical, and lumbar may be involved

All level of the motor system are involved


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The most common presentation:

AMYOTROPIC LATERAL SCLEROSIS

wasting in the upper limbs and spasticity in the lower limbs PROGRESSIVE MUSCULAR ATROPHY SHOW PREDOMINANTLY LOWER MOTOR NEURONE CHANGES

PROGRESSIVE LATERAL SCLEROSIS PYRAMIDAL TRACT DEGENERATION BEFORE MUSCULAR WASTING

PSEUDOBULBAR/BULBAR ;

PROGRESSIVE BULBAR PALSYBRAIN STEM INVOLVEMENT, PREDOMINANTLY SPASTIC: (PSEUDOBULBAR)

PREDOMINANTLY FLACCID (BULBAR)


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AMYOTROPIC LATERAL SCLEROSISthe most common form of motor neuron disease

Atrophy, weakness and fasciculation in their limb

muscle (indicating a lower motor neuron lesion)

Hyperactive reflexes

Extensor plantar responses

No sensory signs

It is this combination of upper and lower motor neuron

signs in all limbs that hallmark of ALS


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FASCICULATION OVER AN AREA MAY BE SEEN WITH

CERVICAL SPONDYLOSIS SYRINGOMYELIA

ACUTE STAGE OF POLIOMYELITIS NEURALGIC AMYOTROPHY THYROTOXIC MYOPATHY

BULBAR SYMPTOMS:

SELECTIVE SWALLOWING DIFFICULTIES WEAKNESS AND NASAL SPEECH

FASCICULATION AND ATROPHY THE TONGUE


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DIAGNOSIS

CLINICAL FEATURESMay leave a little doubt

CONFIRMED BY ELECTROMYOGRAPHY

If indicated muscle biopsy

MYELOGRAM ?(High cervical lesion)

CFS EXAMINATION(Neurosyphilis)


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PROGNOSIS

IF THE PATIENS ASKS IF THE CONDITION IS

POTENTIALLY LETHAL, THE ANSWER MUST IN

ALMOST EVERY CASE BE YES.

Most patients remain mentally alert and are able to

make rational decisions to cope with their increasing

disability


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PARALYTIC POLIO

Persons infected with polio: > 95% asymptomatic viremia and

spontaneous clearing

Flulike prodrome severe generalized myalgias with focal,often asymmetric fasciculation;

followed by weakness that often is severe the legs often are most affected

although any muscle or region can be

involved including diaphragm and bulbar

muscles

Recovery typically is incomplete, atrophy and asymmetric weakness is

often permanent


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POST-POLIO SYNDROME

Occasionally a syndrome develops in former paralytic polio victims

several years following the initial attack

Patients typically complain a diffuse myalgias and recurrence of

weakness of muscles that were affected in the initial attack

The lag between the initial attack and development of so-called post-

polio syndrome often is measured in decades


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PARALYTIC POLIO

POST-POLIO SYNDROME

MANAGEMENT ?


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MYASTHENIA

An acquired autoimmune disorder causing skeletal

muscle fatigue and weakness

Autoantibodies against the acetylcholine receptor

produce weakness that can affect the entire body or

only eye movement Can begin at any time, from early childhood to

extreme old age

The cause of the autoantibodies is not known. Thethymus is implicated in the inception and generation

of the autoantibodies


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Auto antibodies bind to the acetylcholine receptor and cause

increased receptor degradation.

The combination of the binding and the turnover effects resultsloss of receptor so that an action potential in the motor neuron

does not always result in an action potential in the muscle fiber

Thymoma as present in some patients with myasthenia

Onset in non-thymoma cases:

Peak incidence at 10-30 yeas of age, again at 60-70 yeas of age

Myasthenia associated with thymoma:

Peak incidence at 40-50 years of age

Under 40 predominantly affects women


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MYASTHENIA WHICH HAS A DIFFERENT MECHANISM

Neonatal myastheniaTransient illness, lasting less than 1 month, 1 in 8 babies of myasthenic mothers

Juvenile myastheniaMyasthenia in the younger age group, generally similar to those of myasthenia in young adults

Penicillamine-induced myastheniaUsually resolves over several month after drug withdrawal

Lambert-Eaton myasthenic syndromeA presynaptic disorder characterized by impaired release of Ach from the nerve terminal.

60% cases is associated with small cell lung carcinoma

Congenital myasthenia

Familial myasthenia


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SYMPTOMS AND SIGNS

weakness of skeletal muscle is

characteristically increased by exercise,but is not associated with muscle pain

(in contrast to physiological fatigue)

emotional stress, pregnancy and infection can also cause an

exacerbation of symptoms

Ocular muscles

Limb weakness

Bulbar muscle weakness

Respiratory muscle involvement


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CLINICAL CLASSIFICATION

Main groups of acquired myasthenia gravis

Group I:ocular myasthenia gravis (symptoms may remain

persistently confined to the ocular muscles, particularly

when 2 years have elapsed since the onset

Group IIA, B:mild or moderately severe generalized

myasthenia gravis

Group III:acute severe (fulminating) myasthenia gravis

with respiratory muscle involvement

Group IV:late (chronic) severe disease


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INVESTIGATION

Anti-ACHR antibody Antistriated muacle antibody

Edrophonium chloride test

(modification?)

Electromyographic techniques

Thymoma


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MODES OF THERAPY

Anticholinesterase therapy: Pyridostigmine, 30-120 mg orally

Neostigmine bromide, 15-30 mg orally every 3 hours except atnight

Higher dose than those given above are seldom indicated andgreatly increase the risk of cholinergic crisis.

Side-effects are caused by para-sympatithetic stimulation andinclude: - pupillary constriction

- colic

- diarrhoea

- Increased salivation

- Increased sweating

- Increased lacrimation

- Increased bronchial secretions


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MODES OF THERAPY

Corticosteroids:

Prednisolone - suitable- once daily on alternate days to avoid

side-effects

- initial dose 10 mg, increased slowly

out patients: 5-10mg / week in patients: 5-10 mg / dose

to avoid the exacerbation ofsymptoms that can occur when the drug is started at

a high dose- Maximal dose: 1-1.5 mg / kg body weight

- (or symptoms are controlled)


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Thymectomy

Intravenous immunoglobuln Plasma exchange

Improvement is expected although most patients are

maintained on a low-dose corticosteroid after their

initial tapering

Crisis may develop requiring hospitalization,

administration or IVIG or PE, and/or transient

increases in corticosteroid


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MYASTHENIC CRISIS

occurs with inadequate treatment and can beprecipitated by infection.

Treatment consist of:

Control of the airway and assisted ventilation

Anticholinesterase medication

Immunosuppressive drug therapy and/or plasma

exchange


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CHOLINERGIC CRISIS

caused by excess anticholinesterase medication

Treatment consist of:

Control of the airway and assisted ventilation

Temporary withdrawal of anticholinesterase drugs,with later reintroduction at a reduced dose regiment

Immunosuppressive drug therapy and/or plasma

exchange

Atropine, if not already being given

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Motoneuron Diseases