TAM (Treatments and Medicines) NHS HighlandChronic 'length dependent neuropathies' is the most common neuropathy.
Presentation is in adults over 50 years old who have a symmetrical, slowly progressive neuropathy. The symptoms begin in feet and work their way upwards. There may be mild weakness of feet, dysasthesia and mild proprioceptive problems. It can be due to a number of underlying disorders. It is often due to diabetes (including impaired glucose tolerance which can cause a mild and painful neuropathy) but may be idiopathic if blood tests looking for causes prove negative.
LENGTH DEPENDENT NEUROPATHIES (Guidelines)
Warning
Nerve conduction studies in these patients are unlikely to be useful because they will show an axonal neuropathy in the vast majority (and won't explain the underlying cause of the neuropathy.)
A set of 'screening' blood tests is below. Some tests are 'general health bloods' which may point to a systemic issue causing the neuropathy rather than direct pathology. In addition (in those who may be at risk) checking HIV, syphilis and borrelia serology may be helpful.
| Blood Test | Looking for | Outcome |
| Full blood count | General health screen MCV - vitamin B12 deficiency | Investigate underlying abnormality. |
| Renal function | General health screen Neuropathy can be caused by chronic renal failure | Investigate underlying abnormality. Consider renal failure as cause in those with long standing renal failure |
| Liver function | General health screen | Investigate underlying abnormality. Can be associated with hepatitis B infection. Can be associated with hepatitis C infection due to cryoglobulinaemia(refer patient) |
| Thyroid function | Hypothyroidism | Treat. |
| Vitamin B12 | Low vitamin B12 | Investigate and treat. Consider trial of treatment in those with a low normal vitamin B12 level. |
| Immunoglobulin protein, electropheresis and plasma viscosity | Monoclonal gammopathy is more common in those with peripheral neuropathy, particularly IgM paraprotein. IgG (light chain usually lambda) associates with POEMs. | Follow local haematology guidelines. Refer/discuss cases if it is unclear whether result is relevant to neuropathy. |
| Plasma viscosity and CRP | Elevated - consider vasculitis or active autoimmune condition | ANA, ANCA, rheumatoid factor in those with an unexplained elevates plasma viscosity and refer patient. |
| Serum glucose HbAlC | Diabetes | Treat which may slow progression of neuropathy. |
| Glucose tolerance test | Even 'pre-clinical diabetes' can cause a mild, usually painful neuropathy | Healthy lifestyle may slow progression neuropathy and diabetes. |
In addition ask
- Drug history - some do cause neuropathies/ neuritis.
- Family history - if there are first degree relatives with unexplained neuropathies and there are concerns that this is an inherited neuropathy, refer.
There are many causes of neuropathy, two ways of trying to work out the underlying cause is to look at speed of onset and the predominant problem ie weakness or sensory symptoms.
| Diagnosis on the basis of symptom onset. | ||
| Acute | Relapsing | Subacute/Chronic |
| Guillian Barre syndrome Vasculitis Paraneoplastic sensory neuropathy Diabetic lumbosacral radiculoplexus neuropathy (used to be known as diabetic amyotrophy) | Chronic inflammatory demyelinating polyneuropathy (CIDP) Vasculitis Porphyria | Vitamin B12 deficiency Uraemic neuropathy Neuropathy due to hypothyroidism Neuropathy associated with paraproteins Diabetes and impaired glucose tolerance Hereditary neuropathies eg Charcot Marie Tooth |
| Diagnosis on basis of most prominent symptom | |||
| Pure motor weakness. No sensory symptoms or signs on examination | Mixes sensory and motor neuropathy | Predominantly proprioceptive loss causing sensory ataxia | Predominantly pain |
Multifocal motor neuropathy Consider other causes: | Most common - see blood screening for more common causes | Paraneoplastic (check paraneoplastic antibodies and look for underlying cancer) Sjogrens syndrome Cisplatin toxic neuropathy Pyridoxine toxicity IgM paraprotein demyelinating neuropathies (check anti GD1b antibodies) Guillian Barre syndrome uncommonly | Diabetes or impaired glucose tolerance Vasculitic neuropathy Guillian Barre syndrome HIV related neuropathy Toxic neuropathy eg arsenic Amyloid (familial or primary) Fabry's disease Inherited syndromes |
Refer/ discuss with neurology (or if acute issue to medical team)
- Rapidly progressive neuropathy.
- 'Neuropathy' which only has motor and no sensory symptoms/ signs.
- Neuropathy where proprioceptive loss is the prominent symptom.
- Asymmetrical neuropathy, particularly if mononeuritis multiplex is considered.
- Patient with hepatitis C, elevated plasma viscosity or paraproteins.
- Strong family history.
Urgent referral
Any neuropathy which is worsening on a daily or weekly basis should be referred to neurology clinic as urgent. If there is a concern the neuropathy may be Gullain Barre syndrome due to rapid worsening; refer to medical team for in-patient assessment.
If a patient has neuropathic pain; amitriptyline, nortriptyline, gabapentin, pregabalin or duloxetine could be trialled. Seeformulary
Physiotherapy for review of mobility and consideration of aids may be useful and give an opinion as to whether aids eg foot splints may be useful for patients with foot drop.
References:
Overell J. Peripheral neuropathy: pattern recognition for the pragmatist. Practical neurology 2011; 11: 62-70
Sumner CJ, Sheh S, Griffin JW, et al. The spectrum of neuropathy in diabetes and impaired glucose tolerance. Neurology 2003; 60: 108-11
| Abbreviation | Meaning |
| MCV | Mean corpuscular volume |
| CRP | C-reactive protein |
| HbA1C | Hemoglobin A1c |