Diagnosing HNPP

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There are a few things that are common to most of these variations that makes a doctor suspect HNPP:

1.) Everyone has times when an arm or leg "goes to sleep". That's normal. The most common symptom of HNPP is an arm or leg going to sleep also. But in HNPP it tends to lasts longer, sometimes much longer (normal is up to about a minute) and in some cases much more frequently. In individuals with very few symptoms the difference between normal and HNPP can be quite subtle.

2.) Absent or diminished ankle reflexes

3.) EMGs show slowing at the common entrapment sites of wrists elbow and knees. The EMG slowing at the wrist indicates Carpal Tunnel Syndrome which affects as many as 90% of people with HNPP

4.) Nerve biopsies, if done, show sausage-like swellings of myelin sheaths called ‘tomacula'. Tomaculous Neuropathy is usually ( but not 100%) associated with HNPP.



HNPP Should Be Considered in the Following:


Lupski, James R., Charcot-Marie-Tooth Diesease: A Gene-Dosage Effect, Hospital Practice, May, 1997


Once one person in a family has been positively diagnosed, usually via a genetic blood test, others can be diagnosed based on their symptoms and EMG results. I have heard that only the blod test is absolute. But the doctors can be fairly certain about others in the family, using symptoms and EMGs, once one has had the test.

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