Motor Neuron Disease

Posted by e-Medical PPT
Motor neuron diseases:
 Progressive degeneration and loss of motor neurons in the spinal cord with or without similar lesions in the motor nuclei of the brainstem or the motor cortex
Motor neuron disease = Amyotrophic lateral sclerosis
Spinal muscular atrophy:
 Only lower motor neuron signs

Amyotrophic lateral sclerosis (ALS)
Also known as Lou Gehrig’s disease
Degeneration of UMN and LMN
Accuracy of clinical diagnosis ~ 95%

Clinical Manifestations
Weakness : legs, hands, proximal arms, oropharynx
Often hands are affected first, usually asymmetrically
Muscle cramps (hypersensitivity of denervated muscle)
Weight loss
Respiration is usually affected late
Sensation is not clinically affected
Bladder function is spared 
Combination of overactive reflexes with Hoffmann signs in arms with weak, wasted, and fasciculating muscles is virtually pathognomonic of ALS
Course is relentless and progressive without remissions, relapses, or even stable plateaus
Death from respiratory failure, aspiration pneumonitis, or pulmonary embolism
Mean duration of symptoms is about 4 years (27-43 months) ; 20% live > 5 years

Clinical Classification:
Primary Lateral Sclerosis
 Purely UMN
Pseudobulbar Palsy
 Bilateral involvement of corticobulbar pathways
 Pseudobulbar affect
Progressive bulbar palsy
 Prominent dysarthria and dysphagia (LMN)
Progressive Spinal Muscular atrophy
 LMN in limbs; anterior horn cell degeneration

No effective drug therapy
Riluzole (Rilutek)
 Glutamate inhibitor
 Prolongs life by 3 to 6 months
 No visible effect on function or quality of life
Symptomatic (sialorrhea, dysphagia, tracheostomy)
Emotional support
Immunosuppressive therapy
 Only for lymphoproliferatlve disease, monoclonal gammopathy, conduction block or high titers of antibodies to GM, or MAG

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