| Treatment of Neuropathic pain |
| Causes of Painful polyneuropathy |
 | Metabolic
 | Diabetes being the most common: DCCT trial: 69% reduction of neuropathy
in patients receiving intensive insulin therapy
|
| Hypothyroidism |
| Uremia |
| Thiamin, Vit B compound deficiency
|
| Alcohol |
|
| Drug toxicity
| Chemotherapeutic agents: Vincristine, Cisplatin, Taxol
|
| HIV med: dideoxyctidine(ddC) |
|
| Other causes
| HIV infection |
| Eosinophilia-myalgia syndrome |
| Hepatitis |
| Cancer |
| Systemic vasculitis, Connective tissue disorder |
| Hereditary Sensory neuropathy type I
|
|
|
| Principles of Treatment |
| Titrate 1 drug at a time |
| Initiate each drug with the lowest possible dose, slowly titrate up
|
| titrate the dose upward until
| significant pain relief or |
| intolerable side effect |
|
| Continue medications if
| significant pain relief |
| tolerable side effects |
| increased activity & function
|
|
|
| Antidepressants |
| Tricyclics
| Amitryptyline, Nortriptyline, Desipramine all been established as better
than placebo |
| For diabetic neuropathy: 30% of patients will have >50% pain relief
|
| Contrary to past teaching: help both the constant burning and lancinating
pain. |
| Start with the lowest available dose, watch for side effects
|
|
| SSRI: mixed result, overall result is poor
| Controlled study of Fluoxetine on Diabetic neuropathy: no better than
placebo |
| Paroxetine: some benefit |
|
| Venlafaxine (Effexor)
| Reuptake inhibition of Serotonin & NE, minimal anticholinergic,
histaminergic effect |
| Uncontrolled case series reported good pain relief in Diabetic neuropathy |
|
|
| Anticonvulsant |
| Phenytoin: studies reported effective in diabetic neuropathy &
Fabry's disease |
| Carbamazepine: studies reported efficacy in diabetic neuropathy |
| Gabapentin (Neurontin)
|
| Lamotrigine: no controlled study |
| Clonazepan, Valproate: not well studied |
|
| Antiarrhythmic |
| Mexiletine
| Controlled study indicated efficacy |
| Others report intolerable side effects: nausea, anxiety |
| Starting dose 150 mg qd, titrate up |
| May worsen preexisting cardiac arrhythmia, contraindicated in 2nd and 3rd
degree AV block |
| Review
- Drugs Oct 98 |
|
|
| Sympatholytic |
| Clonidine: Clonidine TTS3 may help in some patients with diabetic
neuropathy |
|
| Dextro-methorphan |
| Same component as in cough syrup, effective in painful polyneuropathy |
| Mean dose to be effective high: 381mg/day |
| Side effect frequently encountered at this dose |
|
| Opioids |
| Methadone 1 to 15 mg/day
|
| Other slow release form of opiod |
|
| Topical agents |
| Capsacin: mixed result |
| Lidocaine skin patch - Lidoderm ? may be effective |
| Lidocaine gel: penetrate skin poorly |
|
| Further reading |
| Galer, BS. Neuropathic Pain Syndromes.
Neurology Clinics. Vol 16: 4. Nov 1998. |
