Motor Neuron Disorders Flashcards
What is a motor neuron disease?
Degeneration of the motor neurons (anterior horn cells) in the spinal cord
Clinically presents by progressive wasting and weakness of affected muscles
NO sensory, cerebellar, or mental changes
What acquired motor neuron dx is associated w/ asthma?
Hopkins Syndrome
What are the motor neuron diseases?
Amyotrophic Lateral Sclerosis (ALS) Progressive Bulbar Palsy (PBP) Spinal Muscular Atrophy (SMA) Primary Lateral Sclerosis (PLS) Atypical ALS (w/ frontotemporal dementia)
What is Amyotrophic Lateral Sclerosis also referred to as?
Lou Gehrig’s Dx
What do the parts of Amyotrophic Lateral Sclerosis mean? (Break it down)
A = without Myo = muscle Trophic = nourishment Lateral = side of the spinal cord Sclerosis = hardening/scaring
Are there any definite risk factors for ALS?
No, but some theories are developing
How prevalent is ALS worldwide?
5/100,000
1/20,000
Amyotrophic Lateral Sclerosis is associated w/ mixed U and L motor neuron signs. What are they?
Upper (spasticity, hyperreflexia, Babinski sign)
Lower (atrophy, fasciculations)
What’s the patho-phys of ALS? Age distribution?
Degeneration of anterior horn cells and lateral and ventral corticospinal tracts
- pyramidal Betz cells
- brainstem motor nuclei of the lower cranial nn
- corticospinal/corticobulbar tracts
Etiology unknown
- familial in 5% of cases
Ages 20-60
What’s the clinical presentation of ALS?
Gait disorder
Limb weakness
Speech or swallowing difficulty
Wt loss d/t loss of muscle bulk (50+ lbs)
Cramps
Fasciculations,
Tongue atrophy
What are some of the lab results that contribute to an ALS dg?
EMG: widespread denervation and reinervation
CPK (serum creatinine): normal to slightly inc
CSF: normal
Imaging studies: normal
Muscle biopsy: not req
Important diagnostic negatives of ALS include:
No sensory sxs
Normal mentation
- Steven Hawking still kicks ass at science
No extra-ocular m involvement
Bowel Bladder sxs not prominent
Decubiti rare
- pressure ulcer
What’s the prognosis of ALS?
Poor
Relentlessly progresive (LE = 2-5 years)
No remissions, relapses, or stable plateaus
Death d/t: resp failure, pneumonia (aspirations), pulmonary embolus (d/t immobility)
What’s a tx option in ALS?
Riluzol (Rilutek), glutamate inh
- 3-6 months LE extension
- expensive
What’s the presenting sx in 20% of MND?
Progressive Bulbar Palsy
How does Progressive Bulbar Palsy present?
Involvement of motor nuclei in lower cranial nn
Dysarthria, dysphagia, chewing and resp difficulty
Does Progressive Bulbar Pasly progress to ALS?
Yes, often
How many pts presenting with MND have Progressive Spinal Muscular Atrophy (SMA)?
10%
Are males or females more affected by SMA? What’s the age of onset?
Males
64
What deficits occur in Spinal Muscle Atrophy? Will it progress to ALS?
Lower motor neuron
- weakness, atrophy, resp difficulty, fasciculations
NO upper motor neuron
Can (rarely)
- Better survival rate vs ALS
What’s the focal difference between Spinal Muscular Atrophy and Primary Lateral Sclerosis?
SMA = lower motor neuron involvement
PLS = upper motor neuron involvement
What are the attributes of Primary Lateral Sclerosis?
In 2-4% of pts that present w/ MND
Onset 50-55 yo
UMN (weakness, spasticity, hyperreflexia, Babinski +
Can evolve to ALS
- better survival rate
An infant presents w/ hypotonia, arreflexia, poor suck and difficulty breathing. Diagnosis? Prognosis
Infantile Spinal Muscular Atrophy
Poor, death in 6-12 months
When does Juvenile Spinal Muscular Atrophy present?
Adolescence
