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Health condition

Hereditary neuropathy with pressure palsies

HNPP is an inherited condition in which nerves are unusually vulnerable to pressure, causing recurrent episodes of numbness or weakness after everyday activities like leaning on an elbow.

Key points

What matters most, at a glance.

The essentials in plain English - symptoms, when to seek help, who to see and what treatment looks like.

  • Episodes of painless numbness or weakness follow minor pressure or stretch - crossing legs, leaning on elbows, carrying bags

  • Caused by deletion of one copy of the PMP22 gene; usually inherited from a parent

  • Most episodes recover over days to weeks, though some leave residual symptoms

  • Diagnosis: nerve conduction studies showing focal slowing at entrapment sites, confirmed by genetic testing

  • Management is mainly protective - padding, avoiding sustained pressure, and workplace adjustments

Understanding it

About Hereditary neuropathy with pressure palsies, and what to do next.

In HNPP the nerves lack a normal cushion against mechanical stress, so compressions that most people would never notice - a night with an arm under the pillow, an afternoon kneeling laying flooring - can produce foot drop, a numb hand or wrist weakness lasting days to weeks. Many people accumulate several such episodes, and carpal tunnel syndrome and ulnar neuropathy at the elbow are common companions.

The diagnosis is often missed for years because each episode is treated as an isolated entrapment. The clue is recurrence at multiple sites, sometimes with a family history. Nerve conduction studies show a characteristic pattern of slowing at compression points, and a genetic blood test for the PMP22 deletion confirms it. Treatment is sensible protection rather than medication - elbow pads, avoiding leg-crossing and repetitive strain, care with positioning during surgery - and most people live entirely normal lives once they understand the condition. A neurology assessment brings the pieces together and opens genetic counselling for relatives.

A quiet reminder

This guide is for information, not medical advice.

Your GP knows your history and can tell you which parts apply to you. If in doubt, see them.

Frequently asked

Common questions about Hereditary neuropathy with pressure palsies.

Quick, plain-English answers to what people ask us most.

  • What is hereditary neuropathy with liability to pressure palsies (HNPP)?

    HNPP is a rare genetic nerve condition that causes increased susceptibility to nerve damage from relatively minor pressure or compression, such as leaning on an elbow or crossing legs for a period, leading to temporary or sometimes prolonged weakness or numbness in the affected area. It is related to, but generally milder than, the more well-known Charcot-Marie-Tooth disease. Episodes often occur after seemingly minor pressure that would not affect most people.

  • What causes HNPP?

    It is caused by an inherited deletion affecting the PMP22 gene, which is important for maintaining the protective myelin covering of peripheral nerves, and is inherited in an autosomal dominant pattern, meaning each child of an affected parent has a 50% chance of inheriting the condition. This genetic change makes nerves more vulnerable to pressure-related damage than in people without the condition. Genetic testing can confirm the specific diagnosis.

  • What are the symptoms of HNPP?

    Symptoms include episodes of numbness, tingling, or weakness in a specific area following relatively minor pressure or compression to a nerve, commonly affecting areas such as the wrist (causing symptoms similar to carpal tunnel syndrome), elbow, or leg. Symptoms usually develop after a seemingly minor trigger, such as prolonged leaning on an arm or crossing legs, that would not typically cause problems in someone without the condition. Recovery is often, though not always, complete, sometimes taking days to weeks or occasionally longer.

  • Is HNPP dangerous?

    HNPP itself is not life-threatening, but recurrent nerve compression episodes can, over time, lead to more persistent nerve damage in some people, particularly with repeated pressure to the same nerve. Being aware of the condition and taking simple precautions to avoid prolonged pressure on vulnerable nerve sites can help reduce the frequency and severity of episodes. Most people with HNPP live full, active lives with appropriate awareness and, where needed, occupational adjustments.

  • Is HNPP hereditary?

    Yes, it is an autosomal dominant genetic condition, meaning each child of an affected parent has a 50% chance of inheriting it. Genetic testing can confirm the diagnosis, which is helpful both for the individual and for informing family members who may also carry the genetic change. A family history of similar recurrent, pressure-related nerve symptoms is often an important clue supporting the diagnosis.

  • How is HNPP managed?

    Management focuses on avoiding prolonged pressure on vulnerable nerve sites, such as using cushioned supports, adjusting sitting or sleeping positions, and being mindful of activities known to trigger symptoms for that individual. There is no specific medication to reverse the underlying genetic susceptibility, so prevention and awareness are the main management strategies. Physiotherapy or occupational therapy input can help with practical strategies, particularly if certain activities or work tasks are frequently triggering episodes.

  • Can HNPP be cured?

    There is no cure for the underlying genetic condition, since it reflects a fixed genetic susceptibility present from birth. With good awareness and practical prevention strategies, most people manage very well with only occasional, usually recoverable episodes. Ongoing awareness and adaptation, rather than a specific medical treatment, form the mainstay of long-term management.

  • HNPP vs Charcot-Marie-Tooth disease — what is the difference?

    HNPP and one type of Charcot-Marie-Tooth disease are related, both involving the same PMP22 gene, but HNPP is caused by a deletion of this gene leading to episodic, pressure-related nerve symptoms, whereas the related form of Charcot-Marie-Tooth disease is caused by a duplication of the same gene, leading to a different, generally more progressive pattern of nerve damage. HNPP symptoms tend to be episodic and often substantially or fully recover between episodes, while Charcot-Marie-Tooth disease more typically causes gradually progressive weakness and sensory changes. Genetic testing distinguishes clearly between these related but distinct conditions.

  • When should I see a specialist about possible HNPP?

    See a neurologist if you have recurrent episodes of numbness or weakness following relatively minor pressure to a nerve, particularly with a family history of similar symptoms. A private neurology assessment, including nerve conduction studies and possibly genetic testing, can typically be arranged within about one to two weeks. Getting an accurate diagnosis helps guide practical prevention strategies and provides reassurance about the generally good long-term outlook for this condition.