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Motor Syndromes

Motor
  Differential diagnosis
  Hereditary

Amyotrophic lateral sclerosis
  Hereditary
  Sporadic
  ALS variants
    EOM & Extrapyramidal change
    Primary lateral sclerosis (PLS)
    Primary muscular atrophy (PMA)
    Pseudobulbar paralysis (PBP)
    Western Pacific ALS
Disorders
Amyotrophy
  Lower extremity, benign
  Monomelic
Diabetic amyotrophy
Hand weakness
Hopkins
Infections
Insulinoma
Mitochondrial: SCO2
Motor Neuron Disorders
  Hereditary
  Bulbar
  Lower motor neuron
  Upper motor neuron
  Asymmetric
  Symmetric
  FOSMN
Motor Neuropathy
  Distal
    Hereditary
    Antibodies
      IgG vs GM1
      IgM vs GM1
      IgM vs GalNAc-GD1a
      IgM vs NS6S
  Multifocal motor (MMN)

Myopathies
Painful
Paraneoplastic
  Lymphoma
  Breast
Poliomyelitis & Post-polio syndrome
Rapid onset
  Acute Axonal Motor Neuropathy
  Acute flaccid myelitis
  Poliomyelitis
  Porphyria
Spinal muscular atrophy: Hereditary
  SMN (5q)
  Androgen Receptor (Bulbar SMA)
  Distal SMA (Distal HMN)
  Hexosaminidase A (Tay-Sachs)
  Scapuloperoneal
  Spinal muscular atrophy 2
  X-linked Infant & Arthrogryposis
Spastic paraparesis
Toxic
Motor Neuron Cell Bodies

From: Quain


Motor Neuron Disorders: Differential Diagnoses

Upper & Lower Motor neurons
Before & after concept of synapses established 18

1886

1899
Gowers: A manual of diseases of the nervous system

Motor Neuron & Axon

From: Quain 1912

Motor Unit

Ramon y Cajal

Paraneoplastic Motor Neuropathy

  • Onset: After diagnosis of tumor
  • Epidemiology: Majority male & > 50 years
  • Clinical
    • Weakness
      • Asymmetric; Arms > Legs
      • Mild
      • Lower motor neuron only
      • Normal bulbar
    • Cramps: Painful
    • Painless in some patients
    • Course: Progressive then stabilizes or improves
  • Associated with
  • Laboratory
    • CSF: No cells; Mildly increased protein
    • MRI: Spinal cord normal
    • ? Neuronopathy
  • Animal model: Similar disorder in mice 2° murine leukemic virus
  • Also see: Paraneoplastic Lower Motor Neuron Syndrome
 

Paraneoplastic Lower Motor Neuron Syndrome 8


HOPKINS' SYNDROME: Acute post-asthmatic amyotrophy


Post-Polio Syndrome

  • Diagnostic Criteria: Clinical
    • History of polio
      • Partial or complete neurological & functional recovery
      • Stable function > 15 years
    • Onset of
      • Fatigue
      • Muscle pain
      • Functional loss
        • Usually 2° Musculoskeletal disorder
        • New weakness is rare
    • Neurological examination
      • Lower motor neuron syndrome (confirmed by EMG or MRI)
        • Measurable loss of strength is rare
      • Decreased or absent tendon reflexes
      • No sensory loss
    • Other
      • No other explanation for symptoms
      • Joint pain & cold intolerance may accompany the syndrome
  • Laboratory features
    • CK: Elevated
    • Electrophysiology
    • Muscle pathology
      • Near full recovery of strength & stable
        • Type I muscle fiber predominance
      • Persistent or new weakness
        • 50% type I fibers
        • Angular fibers; Atrophy + Hypertrophy
      • New weakness & high CK
  • Recommended exercise
    • Mild paresis: Resistance training
    • Moderate paresis: Submaximal endurance
    • Severe paresis: None; Joint bracing

Old Polio
Asymmetric atrophy & weakness
  Atrophic right leg (arrow) in patient
    with paralytic polio 70 years in past

Monomelic Amyotrophy


Amyotrophy: Benign Lower Extremity (Crural) 11

Benign lower limb amyotrophy: MRI

From: M Al-Lozi
Legs: Involvement of posterior muscle groups

From: M Al-Lozi
Thigh: Long head of biceps involved

MND: Finger extension weakness + Downbeat nystagmus (FEWDON-MND) 22


"Primary Muscular Atrophy" (PMA) 15

  • Epidemiology
    • Frequency: 7% to 11% of ALS-like disorders
    • Male in 74%: vs 55% in ALS
  • Lower Motor Neuron Syndrome: Widespread
    • Weakness: Distribution
      • Distal & Proximal: Either may be more prominent
      • Asymmetric
      • Often involves paraspinous & respiratory muscles
      • Often spares bulbar musculature
    • Spontaneous motor activity
      • Cramps: Common in legs, at night
      • Fasciculations
    • Upper motor neuron signs
      • Not present at diagnosis
      • After 5 years: 20%
        • More with younger onset age
        • 50% develop in 1st year after diagnosis
    • Pain: Related to immobility
    • Time course
      • Progressive
      • Survival
        • Mean = 4 years: vs 3 years in ALS
        • Range vs typical ALS: Similar, Faster, or Slower  
        • Overall mortality: 68%
  • Laboratory
  • Treatment: No evidence for response
  • Differential diagnosis
  • Pathology
    • Loss of motor neurons in anterior horn of spinal cord
    • Shrinkage of remaining motor neurons
    • Inclusion bodies: Intracytoplasmic, Hyaline

Gowers
Primary muscular atrophy
Wasting: Includes
  paraspinous muscles.

Putnam

Primary Lateral Sclerosis (PLS) 2

Dominant, Adult onset
  4p16
  c9orf72
  FIG4: 6q21
  SPG7
PLS + FTD
  TBK1: 12q14
Recessive, Childhood onset
  ALS2
  ERLIN2
  SIGMAR1
  SPG11
Sporadic, Adult onset
  Mills (Asymmetric) syndrome





From Bramwell: Diseases of the Spinal Cord

PLS: "Sclerosis" of pyramidal tracts
  (Upper thoracic cord)

"About the Case of primary systematic Degeneration of the
Pyramidal tracts with Symptoms of a general spastic Paralysis"

Deutsche Zeitschrift für Nervenheilkunde 1894;5:225246

PLS : Sporadic, Adult onset 14
Pseudobulbar Paralysis, Selective
PLS: Recessive, Juvenile onset 9
  Alsin (ALS2) ; Chromosome 2q33.1; Recessive
PLS: Dominant, Adult onset (PLSA1)
  Chromosome 4p16; Dominant
PLS with Frontotemporal dementia 12
  Sporadic
Patient information

Return to Polyneuropathy Index

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11/17/2020