Peripheral Neuropathy

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Peripheral neuropathies encompass disorders of peripheral nerve cells and fibers which manifest  secondary  to  a  wide  range  of  pathologies  that  can  affect  motor,  sensory,  and  autonomic  fibers.  Peripheral neuropathies can be classified as mononeuropathies, multifocal neuropathies, and poly- neuropathies. Further sub-classifications categorize peripheral neuropathies as axonal,  demyelinating, or mixed types, which is essential for treatment and management purposes.  

Clinical presentation

  • Numbness and paresthesis,
  • Neuropathic pain
  • Extremities weakness
  • Loss of coordination
  • Orthostatic hypotension
  • Cold, pale feet

Investigations 

  • FBP
  • Renal function tests
  • RBG and HbA1c (Diabetes is a common cause of neuropathy)
  • Testing for vitamin and mineral deficiencies such as copper, thiamine, pyridoxine, folate, B12.
  • Infectious workup for HIV, and
  • Thyroid function testing
  • Anti-body testing for specific autoimmune diseases known to cause peripheral neuropathies such
    SLE and rheumatoid arthritis 
  • Nerve conduction studies (NCS) and needle electromyography (EMG) to differentiate axonal from demyelinating neuropathies
  • MRI or CT scans in suspected nerve compression
  • Urine Test for Bence-Jones proteins
  • Genetic testing (for inherited neuropathies)
  • Nerve biopsy in selected cases where expertise and resources are available

Table 8.5 Guide to clinical diagnosis of peripheral neuropathies 

Type 

Clinical features 

Common causes 

Distal Symmetric  Polyneuropathy 
  • Length-dependent: diffuse 
    involvement
  • affects distal segments first 
  • Symptoms  occur  below  the  knees prior to affecting fingertips

Most common cause:     diabetes, Chronic Idiopathic     axonal polyneuropathy, Alcohol, chemotherapy induced. 

Mononeuropathy 
  • Symptoms restricted to distribution of single nerve, myotome, or dermatome
  • Asymmetric reflexes

Entrapment  neuropathies  e.g.,  carpal  tunnel,  peroneal  nerve  entrapment.  Post  traumatic  neuropathies, diabetes 

Mononeuropathy multiplex 

 Occurrence of several  concurrent
mononeuropathies 		Autoimmune vasculitic etiologies
Hereditary
neuropathies
  • Distal  calf  atrophy, hammertoes,  pes cavus
  • Motor deficits ≥ sensory deficits
  • Diffuse areflexia

Genetic diseases 

Pharmacological management 

  • Focus on the management of the underlying disease process if identified.
  • Ensure glucose control in diabetic neuropathy, alcohol cessation in alcoholic neuropathy and correction of vitamin or mineral deficiencies in nutrition related peripheral neuropathies.
  • For drug related neuropathies, stop the offending medicine and give a suitable substitute. e.g., substitute stavudine or didanosine with tenofovir or lamivudine.

Initial management of symmetric polyneuropathies and postherpertic neuralgia

D: pregabalin (PO) 150mg 12hourly for 4-12weeks 

OR 

A: amitriptyline (PO) 50-100mg 12hourly for 4-12weeks 

AND 

B: vitamin B1, B6, and B12 (FDC) (PO) 12hourly for 4-12weeks 

If the initial treatment is not effective, consider one of the combination therapies.

(1)    Gabapentanoid+Tricyclic Antidepressant

D: pregabalin (PO) 150mg 12hourly for 4-12weeks 

AND 

A: amitriptyline (PO) 25-50mg 12hourly for 4-12weeks 

AND 

B: vitamin B1, B6, and B12 (FDC) (PO) 12hourly for 4-12weeks 

(2) Gabapentanoid +Selective Serotonin Reuptake Inhibitors

D: pregabalin (PO) 150mg 12hourly for 4-12weeks 

AND 

S: fluoxetine (PO) 20mg 24hourly for 7days then titrate 12hourly for 4-12weeks 

AND 

B: vitamin B1, B6, and B12 (FDC) (PO) 12hourly for 4-12weeks 

In chronic demyelinating polyneuropathies add steroids 

A: prednisolone (PO) 20-60mg 24hourly for 6weeks (taper down based on response) 

Offer rescue therapy if required, to patients undergoing long term treatment. 

B: tramadol (PO) 50mg 8hourly for 7-14 days 

For localized symptoms, consider topical agents as adjunctive treatment. 

D: lidocaine 5% patches apply for 60minutes. 

For patients on isoniazid related neuropathies, start on 

B: pyridoxine (PO) 25–50 mg 8hourly for 3weeks, then 25mg 24hourly until completion of TB dose. 

Non-pharmacological management 

  • Transcutaneous electrical nerve stimulation (TENS) for pain relief.
  • Educate patients on increased risk of injury and infection due to loss of sensation
  • Recommend wearing socks with closed-toed shoes to decrease the risk of infection.
  • Offer support on cessation to patients with alcohol-induced neuropathy