Clinical Constellations

A look at the different faces of ALS

Amyotrophic Lateral Sclerosis (ALS) lies on the spectrum of disorders known as motor neuron diseases. ALS is not just one presentation or group of symptoms; it can manifest so differently from patient to patient that it can often look like an entirely different disease early on. Below is a brief breakdown of the different ways ALS can present:

For reference:

• UMN signs = upper motor neuron = spasticity, brisk or hyperactive reflexes
• LMN signs = lower motor neuron = decreased tone, twitching (fasciculations) and atrophy (wasting)
• Bulbar signs = trouble speaking (dysarthria), trouble swallowing (dysphagia), facial weakness
• PBA = pseudobulbar affect = emotional disturbances such as excessive or inappropriate laughing or crying

Typical/classic ALS

• Simultaneous UMN/LMN signs
• Weakness starts focally in one limb and then spreads to all four
• Weakness, atrophy, spasticity, fasciculations, cramps, +/- bulbar features and respiratory compromise as disease progresses

Upper motor neuron predominant ALS

• Weakness (without atrophy), cramps, spasticity, PBA, bulbar symptoms
• Lower motor neuron signs absent or restricted to one level (bulbar, cervical, thoracic, lumbar)
• Minimal respiratory involvement early on

Lower motor neuron predominant ALS (Progressive muscular atrophy)

• A pure LMN presentation most commonly considered a variant of ALS
• Slower progression of weakness, decreased muscle tone and fasciculations
• Can start in any body region but hands are usually involved first
• Males are more often affected than females

Lower extremity predominant ALS

• Isolated LE weakness at onset which may spread to the arms
• May have UMN features, LMN features or both

Upper extremity predominant ALS

• Isolated UE weakness at onset which may remain isolated or may spread to the legs
• Note the separate, more benign disease entity of Flail Arm Syndrome

Bulbar onset ALS

• Disease onset with either dysarthria or dysphagia
• 29 months median survival is reduced compared to limb onset ALS
• 25% of ALS cases

PLS (Primary Lateral Sclerosis)

• Sporadic, pure UMN but debated how much LMN is “allowed” on exam
• Slowly progressing symmetric ascending weakness in the LEs with associated cramps

Mill’s variant

• Hemiplegic ALS meaning purely lateralized weakness at onset
• Exceedingly rare

Respiratory onset ALS

• Respiratory weakness as presenting symptom
• Rare, about 2% of all ALS

Since no two patients with ALS are identical in their symptoms and progression of the disease, personalized care plans are crucial in treatment. Our team at Synapticure believes in an individualized approach, including medication regimens, rehabilitation, and access to clinical trials.

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