Makindo Medical Notes.com

Related Subjects: |Analgesia and Pain management |Sedation and Analgesia on ITU |Neuropathic Pain Management |Codeine |Dihydrocodeine |Diamorphine |Morphine |Paracetamol (Acetaminophen)

Neuropathic pain is very challenging to manage because of the heterogeneity of its aetiologies, symptoms and underlying mechanisms

About

• The International Association for the Study of Pain (2011) defines neuropathic pain as ‘pain caused by a lesion or disease of the somatosensory nervous system

Aetiology

• Nerve compression/ entrapment neuropathies (eg carpal tunnel syndrome, thoracic outlet syndrome or piriformis syndrome
• Ischaemic neuropathy, nerve root compression
• Post traumatic neuropathy (trauma, surgery or injection)[3],
• Post-amputation stump and phantom limb pain
• Postherpetic neuralgia
• Complex Regional Pain Syndrome (CRPS)
• Diabetic neuropathy
• Cancer-related neuropathies

Clinical

• Burning, Shooting, Stabbing.
• Neuropathic pain can be spontaneous or evoked, continuous or intermittent
• It is often worse at the end of the day
• Can be made worse by hot or cold, touch or movement
• Patients are unresponsive to conventional analgesics
• Skin in painful area may look different from normal e.g. atrophic or cyanosed
• Patients may have
  • Allodynia – pain produced by a stimulus that does not normally produce pain e.g. touch, pressure, warmth
  • Dysaesthesia – an unpleasant, abnormal sensation
  • Hyperaesthesia – increased sensitivity to stimulation
  • Hyperalgesia – an increased response to a stimulus which is normally painful

Investigations

• May need imaging to exclude structural pathology

Management

• Specialist referral if diagnostic uncertainty, severe pain which significantly limits daily activities, underlying health condition has deteriorated, Continues to work through the medication management section whilst waiting for an appointment
• Manage mental health and other sequelae. Involve therapy who may help with physical therapy in some cases. Splinting and position may help. Exercising for just 30 minutes a day on at least three or four days a week will help some.
• Give Paracetamol +Amitriptyline, start at 10mg and increase by 10mg per week. Analgesic effect is separate from antidepressant effect. Best taken in the evening to reduce 'hangover effect' (6-8pm). Slowly titrate to reduce side effects. Ensure titration occurs even if dose is later reduced. Recommended doses are 25mg -75mg daily in the evening
• Give Paracetamol +Gabapentin: Week 1: 300 mg OD, Week 2 300 mg BD, Week 3 300 mg TDS. Slower titration may be required in the elderly, starting at 100mg and increasing by 100mg increments. Somnolence, peripheral oedema and asthenia may be more frequent in elderly patients

References

• The Pathophysiology of Neuropathic Pain
• NHS guidelines