Coupon Accepted Successfully!


Disorder of Muscle Membrane Excitability

  1. Calcium Channel Disorder Of Muscle :
    1. Hypokalemic Periodic Paralysis (AD)
      1. It is precipitated in some patients by hyperaldosteronism or hyperthyroidism by administration of amphotericin B, or by injection of licorine
      2. Meals high in carbohydrate or sodium can also provoke the attacks
      3. In childhood periodic paralysis is often an episodic event. Patient are unable to move after awakening and gradually recover muscle strength during the next few minutes or hours
      4. Muscles that remain active in sleep such as the diaphragm and cardiac muscle are not affected.
      5. Patients are normal between attacks, but in adult life the attacks become more frequent and the disorder causes progressive myopathy with permanent weakness even between attacks.


  1. ↓ serum K+ during attack with ECG changes
  2. during attack muscle biopsy shows vacoulcer myopathyQ 

2.  Sodium Channel Disorder Of Muscle :

  1. Hyperkalemic Periodic Paralysis (AD)
    1. Causes episodic weakness of limb muscle, cranial and respiratory muscle rarely involvement
    2. The term hyperkalemic is misleading, since patients are often normokalemic during attacks. It is the fact that attacks are precipitated by potassium administration that best defines the disorders
    3. Diagnosis is suggest by modest elevation of the serum potassium level during attacks. In nearly half of patient.
    4. Random serum potassium measurement my suggest the diagnosis, since potassium level elevation are frequent during attack free intervals. EMG evidence of mytonia and finding of vacuoles on muscle biopsy provide supporting data.
  2. Paramyotonia Congenita
    1. It is a temperature related myotonia that is aggravated by cold and relived by warm external temperature
    2. It is characterized by paradoxical myotonia (i.e. myotonia worsening with activity) 

3. Chloride Channel Disorder Of Muscle :

  1. Myotonia Congenita (Thomsen Disease)
    1. It is characterized by weakness and generalized muscular hypertrophy so that affected children resemble body builders
    2. Myotonia is prominent and many develop at age 2 – 3 years.

Test Your Skills Now!
Take a Quiz now
Reviewer Name