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Motor neurone disease
The various forms of adult motor neurone diseaseare classified according to the distribution of the
initial clinical features
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The clinical findings are the consequence of motor neurone
loss in the cortex, brain stem and spinal cord, along withdegeneration in the corticobulbar and corticospinal pathways.
Pathology
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In progressive muscular atrophy
Weakness and wasting of the small hand muscles begin
asymmetrically then extend more uniformly over severalyears. Reflexes are relatively preserved, despite the wasting,
and fasciculation is prominent. Initial involvement of the
lower limbs is less common, presenting usually with foot drop
or wasting of one or both thighs.
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The spinal muscular atrophies (SMAs)
They differ in age at onset and severity of
symptoms.
SMA type I (severe form): Onset is from birth to 6
months. Children are never able to sit without support, and
death usually occurs before the age of 2 years.SMA type II (intermediate form): Onset is before the age
of 18 months. Children are unable to stand or walk without
aid, and death usually occurs after the age of 2 years.
SMA type III (mild form): Onset is after the age of 18
months. Patients have the ability to stand and walk, and
death occurs in adulthood.
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Primary lateral sclerosis is rare. Here there is a
slowly progressive spastic paraparesis with or
without upper limb involvement and without motorneurone loss.
In amyotrophic lateral sclerosis, there is a
combination of spasticity and hyperreflexia in thelower limbs with weakness, wasting and
fasciculation in the upper limbs. Later in the illness
truncal and oropharyngeal muscles are affected.
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Progressive bulbar palsy presents with dysphagia and
dysarthria. The facial muscles atrophy, speech becomes
slurred and aspiration is likely. Weakness and wasting of the
tongue become conspicuous, accompanied by fasciculationand slowing of movement.
include sensory impairment, sphincter
disorders and ocular involvement.
Exclusion criteria
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Lab studies
EMG studies are of considerable value indiagnosis. A combination of fibrillation and
fasciculation potentials with large, prolonged
motor unit potentials is particularly characteristic
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Muscle biopsy shows the changes of chronic
denervation with grouped fibre atrophy and fibre-
type grouping without evidence of inflammatorycell infiltration
Normal muscle contain
random checkerboard-like appearance
Fibre-type grouping
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Medical care in ALS is primarily palliative.
Patients should be involved in regular exercise
and a physical therapy program.
Medications such as baclofen and tizanidinemay be used to relieve severe spasticity.
Riluzole, a glutamate inhibitor, is an FDA-
approved medication for prolongingtracheostomy-free survival.
Treatment:
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Syringomyelia
In syringomyelia cystic cavitation of the spinal cord occurs,
most prominently in the cervical region sometimes inassociation with cystic cavitation in the brain stem
(syringobulbia).
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Causes:
The condition closely coexists with a number of
developmental anomalies close to the cervicocranial
junction, including abnormal fusion of the cervical
vertebrae, Type 1 Chiari malformation.
Syringomyelia may also appear in relationship to anintramedullary tumour, and as a post-traumatic
phenomenon.
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Clinical features
There is prominent dissociated anaesthesia in the cervicaldermatomes, often leading to injuries to the hands.
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Later, touch and proprioceptive function may be affected.
The motor involvement includes weakness then wastingin upper limb muscles and a spastic paraparesis.
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The upper limb reflexes become depressed, the lower limb
reflexes exaggerated. Autonomic dysfunction occurs and
includes a Horners syndrome, altered sweating of the face
and arms, and sphincter disturbance. Kyphoscoliosis is
sometimes found.
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Investigation
CT myelography can demonstrate expanded cord and
delayed opacification of the syringomyelic cavity
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MRIis the procedure of choice,being more accurate in delineating
the extent of cavitation and thecerebellar herniation
Cavity
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Various forms of surgical treatment have been used
including: foramen magnum decompression and
syringoperitoneal or subarachnoid shunting.
Treatment
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