Peripheral neuropathy

Published on 05/05/2015 by admin

Filed under Internal Medicine

Last modified 22/04/2025

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55 Peripheral neuropathy

Instruction

Examine this patient’s legs.

Carry out a neurological examination of this patient’s legs.

Salient features

History

• Progressive and symmetrical numbness in the hands and feet that spreads proximally in a glove and stocking distribution

• Distal weakness, which also ascends

• History of diabetes, alcohol, connective tissue disorder, malignancy.

Examination

• Bilateral symmetrical sensory loss for all modalities with or without motor weakness

• Proceed by looking for evidence of the following (mnemonic: DAD,RUM):

• Diabetes mellitus (diabetic chart, insulin injection sites, insulin pump)
• Alcoholic liver diease (palmar erythema, spider naevi, tender liver)
• Drug history
• Rheumatoid arthritis
• Uraemia
• Malignancy.

• Palpate for thickened nerves and look for Charcot’s joints

• Tell the examiner that you would like to do the following:

• Look for anaemia and jaundice (vitamin B12 deficiency)
• Check urine for sugar
• Take a history of alcohol consumption and a drug history.

Diagnosis

This patient has symmetrical, bilateral sensory loss for touch and pain (lesion) caused by diabetes mellitus (aetiology).

Questions

How are polyneuropathies classified?

• Polyneuropathies can be classified as demyelinating or axonal

• Demyelinated: acute inflammatory demyelinating polyradiculoneuropathy (subtype of Guillain-Barré syndrome), diphtheria, chronic inflammatory polyradiculoneuropathy, Charcot-Marie-Tooth disease type 1
• Axonal: acute motor axonal neuropathy, acute motor and sensory axonal neuropathy, multifocal motor neuropathy, associated with HIV, diabetic, medications, toxins.

• They can also be classified according to the diameter of the affected nerve fibre. Larger fibres are heavily myelinated and, therefore, most subject to processes that damage myelin.

• Most polyneuropathies, including the diabetic type, are axonal.

Mention a few causes of thickened nerves

• Amyloidosis

• Charcot–Marie–Tooth disease

• Leprosy

• Refsum disease (retinitis pigmentosa, deafness and cerebellar damage)

• Déjérine–Sottas disease (hypertrophic peripheral neuropathy).

What are the causes of motor neuropathy?

• Guillain–Barré syndrome

• Peroneal muscular atrophy

• Lead toxicity

• Porphyria

• Dapsone toxicity

• Organophosphorous poisoning.

What are the causes of mononeuritis multiplex?

Mononeuritis multiplex is a neuropathy affecting several nerves and causes include (mnemonic: WARDS, PLC):

• Wegener’s granulomatosis

• Amyloidosis

• Rheumatoid arthritis

• Diabetes mellitus

• SLE

• Polyarteritis nodosa

• Leprosy

• Carcinomatosis, Churg–Strauss syndrome.

Mention a few causes of predominantly sensory neuropathy

• Diabetes mellitus

• Alcoholism

• Deficiency of vitamins B12 and B1

• Chronic renal failure

• Leprosy.

What are the types of neuropathy described in diabetes mellitus?

• Symmetrical, mainly sensory, polyneuropathy

• Asymmetrical, mainly motor, polyneuropathy (diabetic amyotrophy)

• Mononeuropathy

• Autonomic neuropathy.

Be aware there are different classifications (Fig. 55.1).

image

Fig. 55.1 Different clinical presentations of diabetic neuropathies.

What drugs are used for painful peripheral neuropathy of diabetes?

Tricyclic antidepressants, phenytoin, carbamazepine and topical capsaicin.

Advanced-level questions

What are the other effects of alcohol on the central nervous system?

• Wernicke’s encephalopathy (ophthalmoplegia, nystagmus, confusion and neuropathy)

• Korsakoff’s psychosis (recent memory loss and confabulation)

• Cerebellar degeneration

• Marchiafava–Bignami disease (symmetrical demyelination of corpus callosum)

• Central pontine myelinolysis

• Amblyopia

• Epilepsy

• Myopathy and rhabdomyolysis.

K Wernicke (1848–1904) worked in Poland.

SS Korasakoff (1853–1900), a Russian neuropsychiatrist.

J Churg (b. 1910) qualified in Poland and was Professor of Pathology in New York.

L Strauss, a pathologist in New York.

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55 Peripheral neuropathy

Instruction

Examine this patient’s legs.

Carry out a neurological examination of this patient’s legs.

Salient features

History

• Progressive and symmetrical numbness in the hands and feet that spreads proximally in a glove and stocking distribution

• Distal weakness, which also ascends

• History of diabetes, alcohol, connective tissue disorder, malignancy.

Examination

• Bilateral symmetrical sensory loss for all modalities with or without motor weakness

• Proceed by looking for evidence of the following (mnemonic: DAD,RUM):

• Diabetes mellitus (diabetic chart, insulin injection sites, insulin pump)
• Alcoholic liver diease (palmar erythema, spider naevi, tender liver)
• Drug history
• Rheumatoid arthritis
• Uraemia
• Malignancy.

• Palpate for thickened nerves and look for Charcot’s joints

• Tell the examiner that you would like to do the following:

• Look for anaemia and jaundice (vitamin B12 deficiency)
• Check urine for sugar
• Take a history of alcohol consumption and a drug history.

Diagnosis

This patient has symmetrical, bilateral sensory loss for touch and pain (lesion) caused by diabetes mellitus (aetiology).

Questions

How are polyneuropathies classified?

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