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What is Lou Gehrig's disease or ALS amyotrophic lateral sclerosis

In this video Dr Joe Jabre board certified Neurologist discusses ALS also known as Lou Gehrig's disease.

Lou Gehrig’s disease, also known as Amyotrophic Lateral Sclerosis (ALS), is a progressive neurodegenerative disease that affects nerve cells in the brain and spinal cord, leading to loss of muscle control.

What is involved?

Motor Neurons (both Upper and Lower Motor Neurons)

Location

  • Upper Motor Neurons in the brain (motor cortex)
  • Lower Motor Neurons in the brainstem and spinal cord
  • Disease affects motor neurons throughout the nervous system

Common symptoms

  • Progressive muscle weakness, usually starting in hands, feet, or limbs
  • Muscle twitching (fasciculations) in arms, legs, shoulders, or tongue
  • Muscle cramps
  • Slurred speech (dysarthria)
  • Difficulty swallowing (dysphagia)
  • Difficulty breathing as disease progresses
  • No sensory loss (sensation remains intact)
  • No bowel or bladder problems initially
  • Cognitive function usually preserved (though some patients develop frontotemporal dementia)

Onset

  • Usually gradual onset over weeks to months
  • Average age of onset: 55-75 years
  • Can present as limb-onset (70%) or bulbar-onset (25%)
  • Limb-onset: weakness starts in arms or legs
  • Bulbar-onset: speech and swallowing difficulties appear first

Risk factors

  • Age (most common in people 40-70)
  • Slightly more common in men than women
  • Family history (5-10% of cases are familial)
  • Genetic mutations (SOD1 gene and others)
  • Military service (possibly due to environmental exposures)
  • Smoking
  • Lead exposure

Exam

Signs of both Upper Motor Neuron (UMN) and Lower Motor Neuron (LMN) involvement:

Lower Motor Neuron Signs

  • Muscle weakness and atrophy
  • Fasciculations (visible muscle twitching)
  • Hyporeflexia or areflexia in weak, atrophied muscles

Upper Motor Neuron Signs

  • Spasticity (increased muscle tone)
  • Hyperreflexia (brisk reflexes) in non-atrophied muscles
  • Pathological reflexes (Babinski sign, Hoffman sign)
  • Pseudobulbar affect (inappropriate laughing or crying)

Key Examination Points

  • Check for weakness in multiple myotomes
  • Look for fasciculations at rest
  • Assess speech and swallowing
  • Test reflexes throughout
  • Check for tongue atrophy and fasciculations

EMG

EMG is essential for diagnosis and must show widespread denervation.

El Escorial Criteria for EMG

Evidence of LMN degeneration must be present in at least three of four regions:

  1. Bulbar (tongue, face)
  2. Cervical (neck, arm, hand, diaphragm)
  3. Thoracic (back, abdomen)
  4. Lumbosacral (back, leg, foot)

Findings

  • Active denervation (fibrillation potentials, positive sharp waves) in multiple regions
  • Chronic denervation (large motor unit potentials, reduced recruitment)
  • Fasciculation potentials
  • Normal sensory nerve conductions (critical for diagnosis)
  • Motor nerve conductions may show reduced amplitudes but normal or near-normal velocities
  • No conduction block (distinguishes from multifocal motor neuropathy)

Recommendations

  • Multidisciplinary care team (neurologist, pulmonologist, speech therapist, nutritionist, physical therapist)
  • Riluzole (FDA-approved, may slow progression modestly)
  • Edaravone (Radicava) - may slow functional decline in some patients
  • Respiratory support (BiPAP, eventually ventilator if desired)
  • Nutritional support (feeding tube when swallowing becomes unsafe)
  • Physical therapy to maintain mobility
  • Speech therapy and communication devices
  • Hospice and palliative care discussions
  • Genetic counseling for familial cases

What else could it be?

IMPORTANT: Rule out treatable conditions that can mimic ALS:

  • Cervical spondylotic myelopathy - can cause upper and lower motor neuron signs in limbs
  • Multifocal Motor Neuropathy (MMN) - treatable with IVIG, shows conduction block on EMG
  • Kennedy’s Disease (SBMA) - X-linked, slower progression, sensory involvement, gynecomastia
  • Inclusion Body Myositis - progressive weakness, especially finger flexors and quadriceps
  • Primary Lateral Sclerosis (PLS) - pure UMN disease, slower progression
  • Spinal Muscular Atrophy - pure LMN disease
  • Lead poisoning - can cause motor neuropathy
  • Thyroid disorders - can cause weakness and fasciculations
  • Paraneoplastic syndrome - motor neuron disease can be paraneoplastic
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