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Showing posts with label motor neuron disease. Show all posts
Showing posts with label motor neuron disease. Show all posts

What is Kennedýs Disease?

It is an X-Linked Spinobulbar Muscular Atrophy .
Symptoms begins in males in midadult life
The main clinical manifestations are 
  • Lower motor neuron disorder in which there is progressive weakness and wasting of limb and bulbar muscles 
  • Features of androgen insensitivity manifested by gynecomastia and reduced fertility  .
Difference with ALS 
Two findings distinguishing this disorder from ALS are
  • The absence of signs of pyramidal tract disease (spasticity) 
  • The presence of a subtle sensory neuropathy in some patients. 
  • Gynecomastia is also a differentiating features 
Genetic abnormality
The underlying molecular defect in kennedy disease is an expanded trinucleotide repeat (-CAG-) in the first exon of the androgen receptor gene on X chromosome..There is an inverse correlation  between the number of -CAG- repeats and the age of onset of this disease. Genetic abnormality is detected with DNA testing 

What is the prognosis of ALS?

Average survival is 3-5 years after the onset of first symptom
Cause of  death are respiratory failure and insufficiency
Bulbar onset MND has worst prognosis, median survival is 20 months and 5% survive 5 years after the onset
Spinal onset MND has median survival  of 29 months and 15% survive 5 years after the onset
Short survival is associated with the following
Survival in ALS is depended on clinical and laboratory values
Clinical factors that determine the prognosis
  • Increasing age 
  • Recent significant weight loss 
  • Short time from onset to diagnosis 
  • Rapid rate of strength & respiratory loss during 6 months after diagnosis 
  • Respiratory failure 
  • No gastrostomy 
Laboratory factors that determine the prognosis are 
  • Poor pulmonary function < 60% of predicted 
  • Serum chloride: Falling; relation to poor nutrition 
  • EMG 
  • Low CMAPs 
  • Decrement on RNS 
  • EMG: Marked jitter; Low fiber density 

What is the pathology of MND

  • In MND there is  loss of large motor neurons in spinal cord & brainstem
  • Gliosis
  • Spheroids are interwoven disorganized neurofilaments in proximal axons
  • Bunina bodies are intracytoplasmic inclusion bodiesi neurons
  • There is  loss of giant Betz cells , other neuronal loss in DRG & Clarkes’ nucleus
  • 1/3 of motoneurons are destroyed before muscle atrophy becomes apparent
  • Peripheral nerve shows secondary degeneration of axons & myelin
  • Surviving motoneurons will develop collaterals branches
  • Atrophy of the degenerated muscles is a prominent finding

What is motor neuron disease?

Motor neuron disease is a terminal neurodegenerative disease
Motor neurone disease is suspected in the following condition
  • Progressive neurological illness
  • Incurable
  • Rare occurance
  • Group of related diseases
  • Motor neurones are affected
  • Patient usually present with upper and lower limb weakness, speech and swallowing difficulties and breathing difficulties
Every person develops the disease in a different way
Symptoms experienced by a given patient depends on the area of nervous system affected 
90% - 95% of people have the sporadic form. 5-10% have Familial.
This is an adult Illness with most people are over 50. Onset and progression of MND is variable.
Average survival is 2-5 years from onset of first symptoms. 
There is no cure but symptom management and medication   may improve quality or prolong life.
Individual lifetime risk is 1 in 400
Men affected 1.5 times as often as women