HNPP causes episodes of numbness, tingling and/or weakness in response to nerve injury from pressure, stretching or repetitive use. Things that cause these symptoms usually would not affect a normal individual. When injured, the nerves demyelinate or lose their protective covering. This demyelination is what causes the episodes of numbness and weakness in the injured area. The numbness and weakness is referred to as a pressure palsy'. In time, the nerves recover, or partially recover and remyelinate.
These episodes of numbness and weakness can be as brief as a few minutes, or can last several days or even several months . Two to three months seems to be the most common duration of a 'long' pressure palsy, but 6-12 months is not unheard of. Numbness may be as mild as the individual noticing that an area or limb does not have quite the same feeling as surrounding areas or the other side/ Or the numbness may be so severe it feels like the are or limb has been shot full of Novocain. Weakness also can vary between slight and and so severe the individual is, depending on the location of the pressure palsy, unable to move a particular muscle group or an entire limb. A pressure palsy in a hand can result in not being able to hold a pen, much less write, not being able to hold a bar of soap, use a knife to cut, put on socks, button buttons, do zippers or any number of fine motor activities. A pressure palsy involving the arm may result in the arm being totally useless. Another whole arm problem can be not being able to use the arm if it is way from the body, such as for reaching, washing hair, eating, etc. A leg palsy can make walking, driving, or climbing stairs nearly or completely impossible.
The numbness and weakness may gradually go away or it may remain severe for quite some time and then rapidly get better. And sometimes, the numbness and weakness may only partially improve, meaning that there is permanent nerve damage. The amount of time the nerve is compressed seems to play a role in the severity of symptoms.
HNPP can vary greatly in severity and cause very different symptoms even within the same family. It can also cause different symptoms within the same individual! Symptoms can come and go. In approximately one third of people who are diagnosed with HNPP no other family members are recognized to have the disorder. HNPP is also a great imitator of common disorders acquired later in life such as carpal tunnel syndrome ( CMTnet Carpal Tunnel Information - this site lists several useful sources for basic information about Carpal Tunnel.) . It's no wonder that HNPP can be hard to diagnose and the majority of individuals do not even know they have it.
When most people are diagnosed, they are told to avoid crossing their legs, leaning on their elbows and any other activity that causes a pressure palsy. The following are some common activities that do cause them:
There are other symptoms which people with HNPP are reporting (Note: This does NOT mean that everyone with HNPP will develop these symptoms). Many of these are typical symptoms of anyone who has a generalized neuropathy.
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