Updated: 12/8/2020

Huntington Disease

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Snapshot
  • A 20-year-old man presents with a two-year history of motor restlessness that has progressed to uncontrollable choreiform movements. He has moderate dementia with a severe gait disturbance as well as agitation and problems with his mood. MRI scan of the brain shows atrophy of the cerebral cortex and caudate nucleus.
Introduction
  • An autosomal dominant disorder characterized by
    • choreiform movements
    • progressive intellectual deterioration
    • exhibits genetic anticipation
  • Epidemiology
    • demographics
      • symptoms usually begin to appear in the 3rd-5th decade of life
      • both sexes are affected equally
    • incidence
      • 0.38 cases per 100,000 per year
  • Genetic 
    • inheritance
      • autosomal dominant
    • mutation
      • CAG triplet repeat expansion in huntingtin gene (chromosome 4  
        • HUNT 4 an animal, put it in a CAGe
      • demonstrates anticipation
      • mutation leads to atrophy of striatum (especially caudate nucleus) with neuronal loss and gliosis 
      • decrease in the levels of GABA and ACh 
  • Pathophysiology
    • changes in neurotransmitters with Huntington's disease
      • ↑ dopamine (in ventral tegmentum and substantia nigra) and ↓ GABA (in nucleus accumbens) and ACh (in basal nucleus of Meynert)
        • high dopamine can act on the nigro-striatal pathway to result in hyperkinesis
        • high dopamine can act on the meso-limbic pathway to result in psychotic symptoms
Presentation
  • Symptoms
    • progressive choreiform movements of all limbs
    • ataxic gait
    • dementia
    • depression
    • grimacing
Evaluation
  • MRI
    • shows atrophy of caudate
Treatment
  • Pharmacologic
    • no known cure
    • medications used to treat Huntington's disease include 
      • amine-depleting agents (inhibit VMAT, involved in monoamine transport)
        • reserpine
          • ↓ release of amines (dopamine)
        • tetrabenazine
          • ↑ degradation of amines (dopamine)
      • antipsychotics
        • haloperidol
          • dopamine receptor antagonist
          • ↓ effect of excess dopamine resulting in psychotic symptoms
          • antipsychotics
      • muscle relaxants
        • benzodiazepines
Prognosis, Prevention, and Complications
  • Death inevitable
  • Suicide common cause of death
 

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(M1.NE.15.4671) A 32-year-old woman is brought to your office by her husband. The husband says that she had been acting strange lately. She has been forgetful, and she sometimes becomes angered for no reason, which is highly unusual for her. She has also been having random, uncontrollable movements, which are also new. On examination, she appears withdrawn and flat. On further questioning, she reveals that her father died at age 45 from a movement disorder. Which of the following is the pathological hallmark of the patient's condition?
Tested Concept

QID: 107128
FIGURES:
1

Substantia nigra pars compacta

8%

(14/177)

2

Alpha-synuclein intracellular inclusions

8%

(15/177)

3

Loss of neurons in the caudate nucleus and putamen

69%

(123/177)

4

Lipohyalinosis

1%

(2/177)

5

Beta-amyloid plaques

11%

(19/177)

M 2 D

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