Transcript motor nuclei of the lower cranial nerves

DEGENERATIVE DISEASES OF THE NERVES SYSTEM
Motor Neuron Disease in Adults
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generally begins between the ages of 30 and 60 years
Insidious onset, & progressive lead to the death within 3 - 5 years.
annual incidence in the order of 2 per 100,000
a male predominance
may be familial in 5–10% of cases. Otherwise it is a sporadic
disorder.
• characterized by degeneration of anterior horn cells in the spinal
cord (with preference to the cervical & lumber areas), motor nuclei of
the lower cranial nerves in the brainstem, and corticospinal and
corticobulbar pathways
• Cause unknown. Trauma?, electrical shock?, lead poisoning? may
predispose.
Classification: 5 types:
• Progressive Bulbar Palsy:
Bilateral involvement of motor nuclei of lower 4 cranial nerves in the
brain stem,
• Pseudobulbar Palsy:
Bilateral involvement of corticobulbar pathways of 9th , 10th , 12th
cranial nerves,
• Progressive Spinal Muscular Atrophy:
Lower motor neuron signs in the limbs, caused by anterior horn cells
degeneration in the spinal cord,
• Primary Lateral Sclerosis:
Rare. Pure upper motor neuron signs are found in the limbs due to pure
corticospinal tracts involvement,
• Amyotrophic Lateral Sclerosis (most common form):
A mixed upper and lower motor neuron deficit is found in the limbs.
There may also be bulbar involvement of the upper or lower motor
neuron type.
Clinical Findings:
In 20% of patients with amyotrophic lateral sclerosis, the initial
disturbances related to weakness of bulbar muscles (Bulbar /
Pseudobulbar Palsy).
In 40% the initial symptoms due to involvement of upper limbs.
In other 40% the disease involve lower limbs initially.
Bulbar involvement is generally characterized symptomatically by
difficulty in swallowing, chewing, coughing, breathing, and speaking
(dysarthria)
Limbs involvement is characterized symptomatically by easy fatigability,
weakness, stiffness, twitching (fasciculation), wasting, and muscle
cramps (the earliest complain), and there may be vague sensory
complaints and weight loss
Involvement of the limbs is asymmetrical, but ultimately it will become
symmetrical.
Examination reveals upper, or lower, or combination of upper+lower
motor neuron signs e.g: (fasciculation, m. atrophy, spasticity,
upgoing planters) depending upon the type of the disease. There is
no sensory signs
No involvement of extra-ocular muscles or sphincters
Differential diagnosis:
- Cervical spondylosis
- Cervical cord compression by tumor
- Foramen magnum tumor
- Multifocal motor neuropathy
- Chronic lead poisoning
Investigation:
- MRI of cervical spine & foramen magnum to exclude tumors
- EMG (show denervations) & NCS (normal)
- C.P.K enzyme is normal or mildly elevated
- Muscle biopsy (show denervations)
Definitive diagnosis requires the presence of combined upper and lower motor
neuron signs in the bulbar region + at least two spinal regions (cervical,
thoracic, or lumbosacral), or in three spinal regions.
Treatment: no specific treatment available. Riluzole 100 mg/d in 2 divided
doses slightly slow the progression of disease. It prolong life of patient for 2
– 3 months only no more. It act by reduce excitotoxicity by diminishing
glutamate release. Otherwise the treatment is merely symptomatic. NG tube
needed if patient develop sever dysphagia. Tracheotomy & mechanical
ventilation needed when sever respiratory difficulties developed.
Motor Neuron Disease in Children
• a group of genetically determined disorders affecting spinal motor
and cranial motor neurons, characterized by proximal and distal
wasting, fasciculation and weakness of muscles. Involvement is
usually symmetrical & affect proximal muscles more than distal
ones. Treatment just symptomatic.
1) Infantile Spinal Muscular Atrophy (Werdnig-Hoffmann Disease or
SMA-I):
autosomal recessive.
manifests itself within the first 3 months of life.
the infant is floppy (hypotonic)
difficulty with sucking, swallowing, or ventilation (early bulbar
involvement)
the tendon reflexes are normal or depressed
the plantar responses may be absent
It is a rapidly progressive disease
leading to death from respiratory complications by about 3 years of age
2) Intermediate Spinal Muscular Atrophy (Chronic Werdnig-Hoffmann
Disease or SMA-II):
autosomal recessive
begins in the 2nd half of the first year
wasting and weakness of the extremities
bulbar weakness occurs less commonly
progresses slowly & its course is more benign
many patients survive into adulthood
3) Juvenile Spinal Muscular Atrophy (Kugelberg-Welander Disease or
SMA-III):
develops in childhood or early adolescence,
on either a hereditary or sporadic basis.
The usual mode of inheritance is autosomal recessive.
It particularly tends to affect the proximal limb muscles
generally little involvement of the bulbar musculature.
It follows a gradually progressive course
leading to disability in early adult life
Syringomyelia
• Is cavitation of the spinal cord.
• 2 types:
1) Communicating syringomyelia—with communication between the
central canal of the cord and the cavity—is a hydrodynamic disorder
of the CSF pathways.
It associated with:
• Arnold-Chiari malformation (lead to hydrocephalus, cerebellar
ataxia, pyramidal and sensory deficits in the limbs, and
abnormalities of the lower cranial nerves, alone or in any
combination)
• Chronic arachnoiditis of the basal cisterns
2) Non-communicating syringomyelia, there is cystic dilation of the
cord, which is not in communication with the CSF pathways
It caused by:
• trauma (start several years – rarely a few months- after the spinal
injury)
• intramedullary spinal tumors
• spinal arachnoiditis
Clinical features: (asymmetrical)
• a dissociated sensory loss at the level of the lesion; impaired
pinprick and temperature appreciation, but preserved light touch
sensation (involvement of spino-thalamic tracts).
• Cavitation commonly occurs in the cervical region; this can cause a
capelike distribution of sensory loss over one or both shoulders,
diffuse pain in the neck, and radicular pain in the arms
• Sensory impairment lead to trophic changes in upper limbs: painless
skin ulcers, scars, edema, hyperhidrosis, neuropathic joints,
resorption of the terminal phalanges.
• Weakness and wasting of muscles occur at the level of the lesion
because of the involvement of the anterior horns of the cord.
• The tendon reflexes may be depressed at the level of the lesion
• A pyramidal deficit and sphincter disturbances sometimes occur
below the level of the lesion because of involvement of the
corticospinal pathways & autonomic tracts respectively.
• involvement of the T1 segment frequently leads to ipsilateral Horner
syndrome
• Scoliosis, pes cavus.
• Some time the cavitation extend upward into the
lower part of brain stem (medulla oblongata).
For this condition the term “syringobulbia” will
be applied.
• In syringobulbia there will be additional features
of bulbar palsy (absent gag & palatal reflexes,
dysarthria −nasal speech−, dysphagia, nasal
regurgitation, atrophied fasciculated tongue)
Investigation:
MRI, or CT scanning (including the foramen
magnum region to show if there is associated
Chiari malformation) confirms the diagnosis.
They will show cavitation inside the cord that not
take enhancement; a feature differentiate it from
intramedullary spinal tumors
Treatment: is surgical.
Prognosis: is bad because surgical treatment is
disappointing, i.e. condition frequently reoccur
after correct surgery!!
MRI show syringomyelia in 2 patients (Left: T1 weighted of
a case, Right: T2 weighted of other case)
Familial Spastic Paraplegia
• In its pure form, FSP is usually transmitted as an
autosomal trait.
• Most adult-onset cases are dominantly inherited
• It arises in the third or fourth decade
• there is degeneration of the corticospinal tracts
• There is progressive spastic paraparesis beginning in
the distal lower extremities eventually lead to paraplegia
• Late in the illness there may be urinary urgency and
incontinence and sometimes fecal incontinence;
• sexual function tends to be preserved
• Treatment is symptomatic.
Multiple systems atrophy (MSA)
• Sporadic disease
• Usually affect middle-aged and elderly
• Parkinsonism, often without tremor, are combined with
varying degrees of autonomic failure, cerebellar
involvement and pyramidal tract dysfunction
• Combination of parkinsonism with autonomic failure was
called the Shy-Drager syndrome
• Degeneration is more widespread than Parkinson’s
disease
• There is disappointing response to levodopa and other
anti-parkinsonian drugs
• Falls are much more common than in idiopathic
Parkinson's disease. As a result from this:
• life expectancy, is considerably reduced.
• Treatment is just symptomatic