Signs & symptoms

Symptoms

Symptoms vary in severity.
While some (most) people are and remain asymptomatic, others experience mild symptoms and others could experience prolonged disability.

It is important to know that the nervous system in people with HNPP is still able to recover.
However, 50% of the patients do not fully recover, while the other half of the patients recover 100%. 

HNPP can cause episodes of numbness, tingling and weakness or paralysis in various parts of the body. These episodes can last from a few minutes to several hours, days or even several months. For some people the weakness/paralysis will last longer and they might not experience improvement. These episodes are often brought on by mild physical activities that do not cause symptoms in healthy people.
The activities include (cfr. general advice - compression, by sitting with legs crossed or leaning on elbows, repetitively doing the same movements (stereotypic movements) for a prolonged period, and over-stretching of the arms or legs.

The most common problem sites involve nerves in the wrists, elbows, and knees. The fingers, hands, shoulders, ankles, feet and scalp can also be affected, since they are also part of the peripheral nervous system.

Some people experience fatigue, generalized weakness, muscle cramps, pain in the muscles or bones, or lower back pain.

The cranial nerves can also be afflicted by HNPP. For instance, partial hearing loss and facial numbness have been reported by patients with HNPP.

Overview (non-exhaustive list)

Sensory loss

- Focal sensory loss (f.e. When  leaning against something => sensory loss in a piece of skin)

Muscles

- Focal weakness (muscle weakness)
- Tingling
- Loss of muscle function (palsy)
- Muscle cramps
- Muscle weakness (difficulty performing daily activities):
  examples: not being able to lift arms above head
- Carpal tunnel syndrome (impairing the ability to use the fingers, hands, and wrists)
- Foot drop/wrist drop
- Brachial plexopathy (lack of  movement/feeling in shoulder)
(https://pubmed.ncbi.nlm.nih.gov/34565753/: Hatake S, Shimizu F, Oishi M, Kimura K, Kanda T. [An 18-year-old man of hereditary neuropathy with liability to pressure palsies presenting with bilateral brachial plexopathy during military training]. Rinsho Shinkeigaku. 2021 Oct 28;61(10):676-680. Japanese. doi: 10.5692/clinicalneurol.cn-001619. Epub 2021 Sep 25. PMID: 34565753.): sometimes discovered during military training (carrying heavy back pack)
- Paresthesia (abnormal sensations: tingling, shooting pains)
- Pregnancy can influence the symptoms:
 Hormone levels
 Weight gain
 Delivery: prolonged position during delivery can cause problems

Pain

Although a lot of sources claim that pain is not a part of HNPP, recent research and patient testimonies have proved otherwise.
Note from Doctor Jun Li (video conference 22nd of March 2024): The pain that people feel is not necessarily neuropathic pain.
For instance: If one ankle is weak and the other is strong, this could cause pain or problems. Pain can be caused by other reasons.
Pain is quite common in people with HNPP.


Pain that can occur (non exhaustive list):
- Pain in the limbs
- (Lower) back pain
- Lancinating pain (feeling like electrical shocks)
- Diffuse pain
- Pain at the sites of entrapment
- Pain as if something is bruised
- Pain during activities

Sources:
https://pubmed.ncbi.nlm.nih.gov/31536037/, Dukefoss TT, Kleggetveit IP, Helås T, Jørum E. Pain and small-fiber affection in hereditary neuropathy with liability to pressure palsies (HNPP). Scand J Pain. 2019 Dec 18;20(1):61-68. doi: 10.1515/sjpain-2019-0090. PMID: 31536037.  https://bestfoot4wardblog.com/2020/02/20/hnpp-the-latest/

General fatigue

Fatigue is common and severe among patients with HNPP whose disabilities are minimal by conventional outcome measures. Therapeutic interventions targeting fatigue have the potential to improve quality of life and may serve as a robust outcome measure to show longitudinal changes for patients with HNPP.
The patients wore a wrist-worn device that captured fatigue ratings five times a day.
(Source: Fatigue in patients with hereditary neuropathy with liability to pressure palsies. https://pubmed.ncbi.nlm.nih.gov/32856791/: Fritz NE, Chen Y, Waters L, Saba S, Hackett M, Mada FC, Li J. Fatigue in patients with hereditary neuropathy with liability to pressure palsies. Ann Clin Transl Neurol. 2020 Aug;7(8):1400-1409. doi: 10.1002/acn3.51133. Epub 2020 Jul 28. PMID: 32856791; PMCID: PMC7448142.)

Note from Doctor Jun Li (video conference 22nd of March 2024): Surprisingly the fatigue score is higher than in people with MS.

Rare symptoms

Rare symptoms (non-exhaustive list)

- Partial hearing loss (https://pubmed.ncbi.nlm.nih.gov/15891642/: Verhagen WI, Huygen PL, Gabreëls-Festen AA, Engelhart M, van Mierlo PJ, van Engelen BG. Sensorineural hearing impairment in patients with Pmp22 duplication, deletion, and frameshift mutations. Otol Neurotol. 2005 May;26(3):405-14. doi: 10.1097/01.mao.0000169769.93173.df. PMID: 15891642.)

 
- Facial numbness (Bells Palsy alike)
Sources: (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8635109/pdf/fneur-12-726437.pdf: De Kock L, Van der Cruyssen F, Gruijthuijsen L and Politis C (2021) Facial Paresthesia, a Rare Manifestation of Hereditary Neuropathy With Liability to Pressure Palsies: A Case Report. Front. Neurol. 12:726437. doi: 10.3389/fneur.2021.726437  and https://n.neurology.org/content/51/1/320?ijkey=0d03cc9d70ba1482ebb17076007d525eb0bf69ac&keytype2=tf_ipsecsha: Poloni TE, Merlo IM, Alfonsi E, Marinou-Aktipi K, Botti S, Arrigo A, Taroni F, Ceroni M. Facial nerve is liable to pressure palsy. Neurology. 1998 Jul;51(1):320-2. doi: 10.1212/wnl.51.1.320. PMID: 9674839. )
 

Misdiagnoses that might occur (non-exhaustive list)

A lot of patients that were diagnosed with HNPP have been looking for a diagnoses for a (very) long time.
Most patients get misdiagnosed because of the variability of the symptoms and because the disease is not well-known in a lot of regions.
Even neurologists don't always know the disease.

Misdiagnoses that might occur:


(Sources: https://bestfoot4wardblog.com/2020/02/20/hnpp-the-latest/, https://pubmed.ncbi.nlm.nih.gov/36197172/: Zhu J, Tong X, Li Y, Li G, Pi Z. Hereditary neuropathy with liability to pressure palsies misdiagnosed as Guillain-Barré Syndrome: A case report. Medicine (Baltimore). 2022 Sep 23;101(38):e30768. doi: 10.1097/MD.0000000000030768. PMID: 36197172; PMCID: PMC9509038. , https://www.cmtausa.org/understanding-cmt/types-of-cmt/hereditary-neuropathy-with-liability-to-pressure-palsies/)