Ch 5 - EDX: Motor Neuron Disease (MND) Flashcards
What is affected in motor neuron disease?
Progressive degeneration of the motor neurons in the spinal cord, brainstem, or motor cortex
What are examples of lower motor neuron diseases?
Spinal muscle atrophy (SMA)
Poliomyelitis/Post-polio
syndrome
What are examples of lower and upper motor neuron diseases?
Amyotrophic lateral sclerosis
ALS
What are examples of upper motor neuron diseases?
Primary lateral sclerosis (PLS)
Hereditary spastic paraplegia
What are signs of lower motor neuron diseases?
Atrophy
Flaccidity
Hyporeflexia
Fasciculations
What are signs of upper motor neuron diseases?
Weakness
Spasticity
Hyperreflexia
Upgoing plantar response
What should be evaluated on EDX in motor neuron disease?
Evaluation of at least 1 upper and 1 lower limb
Start with most severely affected muscles
What should be ruled out on EDX of motor neuron disease?
Treatable neuropathies such as multifocal motor neuropathy
What is seen on SNAP in motor neuron disease?
Typically normal
Can be ABN with hereditary spastic paraplegia and
spinobulbar muscular atrophy
What is seen on CMAP in motor neuron disease?
ABN in weak muscles with asymmetry side to side
Dec CV
Prolonged latencies
What is seen on EMG in motor neuron disease?
Active denervation with reinnervation must be found in 3 of 4 body segments (craniobulbar, cervical, thoracic, and lumbosacral). At least 2 muscles with different innervations should be abnormal.
Which motor neuron diseases will have Fibs and + sharp waves on EMG?
- SMA Type I
- SMA Type II
- SMA Type III
- Amyotrophic lateral sclerosis (ALS)
- Poliomyelitis
Which motor neuron diseases will have fasiculations on EMG?
- ALS
- Poliomyelitis
- Post-polio syndrome
Which motor neuron diseases will have complex repetitive discharges on EMG?
• SMA Type III
Where should a monopolar needle be placed during EMG to evaluate the diaphragm?
Inserted through the eighth or ninth intercostal space at the anterior axillary line
What is evaluated on EMG during expiration?
MUAP of the intercostal muscles is recruited during expiration and is higher in amplitude
than the diaphragm
What is evaluated on EMG during inspiration?
Diaphragm recruitment
What is the inheritance and onset of SMA Type I (Werding-Hoffman disease)?
Autosomal recessive
3 to 6 months
What is the course of SMA Type I (Werding-Hoffman disease)?
Rapid, fatal respiratory failure
Death by 2 to 3 yo
Worst prognosis
What is the clinical presentation of SMA Type I (Werding-Hoffman disease)?
• Floppy baby/ hypotonia • Unable to reach milestones • Progressive weakness • Absent MSR • Difficulty feeding • Weak cry • Frog-legged position • Tongue fasciculations • Paradoxical breathing • Never sits independently
What is spared in SMA Type I (Werding-Hoffman disease)?
- Facial muscle affected least
- Extraocular muscles intact
- Sphincter muscles are spared
What is seen on labs and muscle biopsy in all SMA types?
Increase CPK levels
Hyper/atrophic fibers
What is the inheritance pattern and onset of SMA Type II (Chronic Werding-Hoffman disease)?
Autosomal recessive
2 to 12 months
What is the course of SMA Type II (Chronic Werding-Hoffman disease)?
Slower, fatal respiratory failure
WC by 2-3yo
Death ~10 yo
What is the clinical presentation of SMA Type II (Chronic Werding-Hoffman disease)?
• Floppy baby/ hypotonia • Gradual progressive limb weakness; upper > lower • Absent MSR • Face least affected • Kyphoscoliosis • Equinus deformity of the feet • ± Tongue fasciculations • Progressive pulmonary involvement
What is the expected function of SMA Type II (Chronic Werding-Hoffman disease)?
• Independent sitting
• Assistive devices for
standing and walking
• WC by 2-3 yo
What is the inheritance pattern and onset of SMA Type III (Kugelberg-Welander disease)?
Autosomal recessive/dominant
2 to 15 years
What is the course of SMA Type III (Kugelberg-Welander disease)?
Slow
Normal life expectancy
Wheelchair by 30 years of age
What is the clinical presentation of SMA Type III (Kugelberg-Welander disease)?
• Symmetric weakness: lower limb then upper limb • Abnormal MSR • ± Gowers’ sign • ± Calf pseudohypertrophy • ± Dysphagia • ± Dysarthria • Tongue fasciculations—late onset
What is the expected function of SMA Type III (Kugelberg-Welander disease)?
• Normal intelligence
• Independent
standing/walking
• WC by 30 yo
What is the pathology of ALS?
Degeneration of the
anterior horn cell
What is the onset of ALS?
Most commonly in men after the sixth decade
What are the first signs of ALS?
Asymmetric atrophy
Weakness
Fasciculations
What are the pseudobulbar signs of ALS?
Difficulty chewing, swallowing, speech along with unprovoked emotional
outbursts
What is typically spared in ALS?
- Bowel and bladder
- Sensation
- Extraocular muscles
What is the prognosis of ALS?
50% die w/in 3 years
30% live for 5 years
10% live for 10 years
WC by 12-18 months
What are predictors of survival of ALS?
Younger is better
Severity of onset
Pulmonary function
ABN sniff test=poor survival
What is the anatomic pathology of Poliomyelitis?
Degeneration of the anterior horn cell
What is the etiology of Poliomyelitis?
Picornavirus orally enters the body and spreads via lymphoid system leading to orphaned muscle fibers
What are signs of initial infection with Poliomyelitis?
Fever Malaise Sore throat Vomiting Headache Back and neck pain/ stiffness
What is the clinical presentation of Poliomyelitis?
- Weakness
- Absent MSR
- Bulbar palsies
- Sensation spared
- Autonomic dysfunction can occur
What is the prognosis of Poliomyelitis?
– 25%: Severe disability
– 25%: Mild disability
– 50%: Complete recovery
What is the mortality rate of Poliomyelitis?
1%-4% chance in children
10% chance in adults with bulbar and respiratory involvement
What is the anatomic pathology of Post Poliomyelitis syndrome?
Loss of the anterior horn cell
What is the etiology of Post Poliomyelitis syndrome?
Death of the motor neuron due to aging
Burnout of motor unit from increased metabolic demand
What is the Halstead-Ross criteria of Post Poliomyelitis syndrome?
- Hx of a previous dx
- Recovery of function
- Stability for ~15 years
- Return of sx
- No other medical problems to explain new sx (weakness, atrophy)