What is the best approach to manage neurogenic pruritis in a patient?

Management of Neuropathic Pruritus

Start with gabapentin 300 mg at bedtime, titrating up to 900-3600 mg daily in divided doses, as this is the primary systemic treatment recommended by the British Journal of Dermatology guidelines for neuropathic pruritus. 1, 2

Diagnostic Confirmation

Before initiating treatment, confirm the neuropathic nature of the pruritus by identifying these key features:

• Patient describes a "deep" or "internal" sensation rather than superficial itching, which distinguishes neuropathic from inflammatory pruritus 1
• Accompanying sensory symptoms including burning, tingling, stinging, or paresthesia strongly suggest neuropathic origin 3, 1
• Localized distribution corresponding to a specific dermatome indicates nerve compression at that level 1
• Skin biopsy showing reduced intraepidermal nerve fiber density confirms small fiber neuropathy if diagnosis remains uncertain, though this is optional and not routinely required 1, 2

Treatment Algorithm

First-Line: Topical Therapy

• Apply topical menthol 0.5% or pramoxine 2-3 times daily to the affected area for immediate symptomatic relief 1
• Topical doxepin can be used but is limited to maximum 12 g daily for up to 8 days and 10% body surface area 2
• Topical capsaicin has demonstrated efficacy in neuropathic itch, though it may cause initial burning 4, 5
• Expect improvement within 1-2 weeks with topical agents 1

Second-Line: Systemic Gabapentinoids

• Gabapentin 300 mg at bedtime, titrated to 900-3600 mg daily in divided doses, is the primary systemic treatment 1, 2
• Pregabalin serves as an alternative anticonvulsant if gabapentin is not tolerated 2, 6
• These medications work by modulating neuronal pathways involved in neuropathic itch transmission 7

Third-Line: Alternative Systemic Agents

If gabapentinoids fail or are not tolerated after 8-12 weeks:

• SSRIs (paroxetine or fluvoxamine) or mirtazapine can be considered 2, 8
• Naltrexone or other opioid receptor modulators may provide benefit 2, 8
• Tricyclic antidepressants have shown antipruritic efficacy in neuropathic conditions 9, 7

Adjunctive Non-Pharmacological Interventions

• Behavioral interventions including education on trigger avoidance, relaxation techniques, cognitive restructuring, and habit reversal training for distressed patients 2, 8
• Phototherapy (NB-UVB) may provide symptomatic relief in selected cases 2
• Transcutaneous electrical nerve stimulation (TENS) and physical therapy have value in specific cases 4

Critical Pitfalls to Avoid

• Never use antihistamines alone for neuropathic pruritus—they are ineffective and cause sedation/cognitive impairment, especially in elderly patients 1
• Avoid gabapentin in hepatic disease as it can worsen hepatic encephalopathy; gabapentin is specifically contraindicated for hepatic pruritus 2, 8
• Do not prematurely diagnose as psychogenic without thorough investigation for physical causes, as neuropathic itch can mimic psychiatric presentations 3, 9
• Avoid long-term sedative antihistamines except in palliative care due to potential dementia risk 8

When to Refer

• Refer to neurology if progressive neurological symptoms develop or if standard treatments fail after 8-12 weeks 1
• Reconsider diagnosis and refer to dermatology or neurology if no improvement after 12 weeks of appropriate therapy 1
• Cervical spine imaging may be necessary if mechanical nerve compression is suspected based on dermatomal distribution 1

Underlying Causes to Investigate

• Peripheral nerve compression causing postherpetic neuropathy, brachioradial pruritus, or notalgia paresthetica 3
• Central nervous system lesions from spinal cord tumors, neurofibromatosis type 1, or multiple sclerosis 3
• Small fiber neuropathy associated with diabetes mellitus, HIV, sarcoidosis, Guillain-Barré syndrome, or neurofibromatosis 3, 1
• Cervical spine pathology including nerve root compression from degenerative disease or disc herniation 1

Psychosocial Considerations

Up to one-third of patients with chronic neuropathic pruritus develop significant psychosocial morbidity including anxiety and depression 3, 2. Referral to liaison psychiatry or psychology may be beneficial, and patient support groups can provide additional benefit 2, 8. Chronic pruritus significantly reduces quality of life comparable to chronic pain, with deranged sleep patterns contributing to exacerbations 3.