Ch 5 - EDX: Motor Neuron Disease (MND) Flashcards by Chris Garrison

What is affected in motor neuron disease?

Progressive degeneration of the motor neurons in the spinal cord, brainstem, or motor cortex

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What are examples of lower motor neuron diseases?

Spinal muscle atrophy (SMA)
Poliomyelitis/Post-polio
syndrome

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What are examples of lower and upper motor neuron diseases?

Amyotrophic lateral sclerosis

ALS

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What are examples of upper motor neuron diseases?

Primary lateral sclerosis (PLS)

Hereditary spastic paraplegia

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What are signs of lower motor neuron diseases?

Atrophy
Flaccidity
Hyporeflexia
Fasciculations

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What are signs of upper motor neuron diseases?

Weakness
Spasticity
Hyperreflexia
Upgoing plantar response

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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

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What should be ruled out on EDX of motor neuron disease?

Treatable neuropathies such as multifocal motor neuropathy

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What is seen on SNAP in motor neuron disease?

Typically normal
Can be ABN with hereditary spastic paraplegia and
spinobulbar muscular atrophy

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What is seen on CMAP in motor neuron disease?

ABN in weak muscles with asymmetry side to side
Dec CV
Prolonged latencies

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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.

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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

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Which motor neuron diseases will have fasiculations on EMG?

ALS
Poliomyelitis
Post-polio syndrome

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Which motor neuron diseases will have complex repetitive discharges on EMG?

• SMA Type III

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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

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What is evaluated on EMG during expiration?

MUAP of the intercostal muscles is recruited during expiration and is higher in amplitude
than the diaphragm

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What is evaluated on EMG during inspiration?

Diaphragm recruitment

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What is the etiology and onset of SMA Type I (Werding-Hoffman disease)?

Autosomal recessive

3 to 6 months

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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 etiology 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 etiology 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?

1. Hx of a previous dx 2. Recovery of function 3. Stability for ~15 years 4. Return of sx 5. No other medical problems to explain new sx (weakness, atrophy)