What are the symptoms of HNPP?

HNPPranges in severity some people get no symptoms at all or find it a minor nuisance, while others are so badly affected they can't even move the affected limb.

Most people with HNPP have attacks of numbness, tingling and muscle weakness in:

• the leg or foot which can make walking, climbing stairs and driving difficult or impossible, and can result in foot drop (inability tolift the front part of the foot because of muscle weakness)
• the elbow, wrist or hands which can result in "wrist drop" and loss of sensation in the index finger and thumb (symptoms similar to those of carpal tunnel syndrome ), making fine movements such asfastening buttons impossible

These symptoms happen because the layer of proteincovering and protectingthe nerve(the myelin sheath) is faulty. For more information, see What's the cause?

Some episodes last just a few minutes, while others can last months.

Triggers

Symptomscan betriggered by simple actions, usually:

• squashingthe nerve by leaning on an affected arm, for example
• repetitive movement youmay be able to do an activity one day without problems, but find it increasingly difficult if the same activity is continued many days in a row (you're thought to be damaging more and more fibres inside the nerve each time)
• stretching the vulnerable limb

Progression of the disease

HNPP is not life-threatening.How severe it is and the way it progresses can differ greatly from person to person.

Symptoms usually start in theteenage years or 20s-30s, although they can sometimes develop later in life or in childhood.

Some people start off with mild symptoms, or episodes in one particular area that come and go.

About half of peoplewith HNPP fully recover after experiencing symptoms, never to have another episode, as the nerves have rebuilt their protective covering.

But the nerves don't completely recover for everyone with HNPP. For some people, the nerve only partially heals after being damaged, and they are left with recurrent or permanent nerve symptoms and muscle problems. However, these symptoms are usually mild, and it's unusual to be left with asevere disability.