Anterior Horn Cell Disease

Question 1

motor neuron dz- is what?

Answer 1

• disorders that cause degeneration of motor neurons (ant horn cells)
• characterized clinically- progressive wasting, weakness of affected m’s (w/o sensory, cerebellar, or mental changes)

Question 2

motor neuron dx- diff dx

Answer 2

• idiopathic
• toxins- heavy metals
• infections- polio, west nile virus, HIV
• metabolic- alpha-glucosidase (acid maltase) def (Pompe dz)
• familial (rare)
• mult radiculopathies

Question 3

Motor neuron dz- idiopathic- types

Answer 3

• ALS (amyotrophic lateral sclerosis)
• PBP (progressive bulbar palsy)- lower CN’s
• SMA (spinal muscular atrophy)
• PLS (primary lateral sclerosis)- only CST involved

Question 4

Monomelic (1 limb) Amyotrophy

Answer 4

• UE (Hirayama’s dz)

- LE

Question 5

ALS

Answer 5

(amyotrophic lateral sclerosis/ Lou Gehrig’s dz)

• A= without
• Myo= muscle
• trophic= nourishment
• lateral= side of spinal cord
• sclerosis= hardening/scarring

Question 6

ALS- what is it?

Answer 6

• no definite risk factors; 5/100,000
• mixed upper (spasticity, hyperreflexia, babinski sign) and lower (atrophy, fasciculations) motor neuron signs
• may also be bulbar involvement

Question 7

ALS- pathophysiology

Answer 7

• degeneration of ant horn cells and lateral and ventral CSTs
• etiology unknown!:
• genetic
• head trauma
• environmental- Guam
• virus- HIV
• professional athletes

Question 8

ALS- in who? characterized by?

Answer 8

• 20-60 yo
• degeneration of pyramidal (Betz) cells, ant horn cells, brainstem motor nuclei of lower CNs, and corticospinal and corticobulbar tracts (alone or in combo)
• usually sporadic! (familial- 5%)

Question 9

ALS- clinical presentation

Answer 9

• gait disorder, limb weakness, speech or swallowing difficulty- initial complaints
• unexplained weight loss (loss of m bulk), cramps, fasciculations
• tongue atrophy and fasciculations

Question 10

ALS- dx testing

Answer 10

• EMG- widespread denervation and reinnervation
• CPK- normal or slightly inc
• CSF- normal
• imaging studies- normal
• m bx- only in confusing cases

Question 11

ALS- Rule of Thumb Diagnostic Negatives

Answer 11

• no sensory sx’s
• normal mentation
• no extraocular m involvement
• bowel or bladder sx’s not prominent
• Decubiti rare (numbness/cant feel P on skin)

Question 12

ALS- prognosis

Answer 12

• progressive dz
• death- resp failure, pneumonia (aspiration), PE
• mean survival duration from dx- 2-5 yrs
• tx- supportive (feeding tubes, ventilatory support, sx meds)
• Riluzol (Rilutek)- glutamate inhibitor- prolongs life by 3-6 months (expensive)

Question 13

PBP (progressive bulbar palsy)

Answer 13

• presenting sx in 20% of MND cases
• motor nuclei of lower CNs
• dysarthria, dysphagia, chewing diff, resp diff
• often progresses to generalized involvement (ALS)

Question 14

(Progressive) Spinal Muscular Atrophy

Answer 14

• 10% of pts w MND
• M>F, onset is 64 yo
• LMN deficits- degeneration of ant horn cells
• no UMN involvement
• weakness, atrophy, resp difficulty
• can progress to ALS- usually doesnt
• survival rate better than ALS

Question 15

Primary Lateral Sclerosis

Answer 15

• 2-4% of MND pts
• age at onset 50-55 yo
• UMN (corticospinal) deficit
• weakness, spasticity, hyperreflexia, Babinski signs
• slow progression- can evolve into ALS
• survival rate better than ALS

Question 16

Childhood motor neuron dz

Answer 16

• Infantile SMA (Werdnig-Hoffman dz)- hypotonia, arreflexia, poor suck, breathing diff, death in 6-12 months
• Intermediate SMA (chronic Werdnig-Hoffman dz)
• Juvenile SMA (Kugelberg-Welander dz)- milder than Werdnig-Hoffman