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Post herpetic Ophthalmic Neuralgia occurring as a sequela to Herpes Zoster Ophthalmicus is not rare and is characterised by severe burning and lancinating pain often associated with allodynia. There is no effective treatment for intractable post herpetic neuralgia. Here we report such a case where regional nerve blocks helped in the management of severe acute pain and prevention of chronic neuralgia.

Varicella zoster virus causes Herpes zoster with chicken pox as primary disease and shingles involving a posterior nerve root as a secondary event especially in an immunosuppressed host.

Herpes zoster ophthalmicus is said to occur when eye and face are affected due to involvement of ophthalmic division of trigeminal nerve. Here the chief focus of infection is the gasserian ganglion from where the virus travels down one or more of its branches affecting always supraorbital, supra trochlear and infratrochlear nerves and frequently the nasal branch. The infraorbital nerve is rarely affected. It is very rarely bilateral. If nasociliary branch is affected, it is likely that eye will also be involved because nasociliary is the main sensory nerve of the eye (Hutchinson’s sign).

Neuralgia frequently follows an attack of herpes zoster ophthalmicus. This is characterized by allodynia which could become a chronic problem. Patients who have intractable neuralgia are observed to have high concentrations of interleukin-8 in their cerebrospinal fluid. Interleukin-8 is usually associated with inflammatory pain.^5,6 There are anecdotal reports that methyl prednisolone acetate administration provided lasting pain relief in patients with post herpetic neuralgia. However the effectiveness of methyl prednisolone is offset by several serious potential neurological complications such as tranverse myelitis, cauda equina syndrome chronic arachnoiditis, chemical meningitis and urinary retention,^8,9 attributable to sensitivity to preservatives used.

Gabapentin, an anticonvulsant drug, is said to have immediate and appreciable pain relief in post herpetic neuralgia. It has no side effects. However it requires further studies to determine its efficacy.

Neural blockade is an important therapeutic alternative for well-selected patients with severe pain and thus an important focus for the anesthesiologist with specialized training in pain management. It requires careful patient selection and attention to technique. Peripheral neurolytic blocks by alcohols and phenols etc. require that the localization of needles must be undertaken with great precision and certainty. Also they produce non-selective, indiscriminative tissue damage, the consequences of which are lasting. They are therefore preferred only in patients with predictably short life expectancies. The neurotoxicty of intrathecal or epidural steroids can be avoided by giving them either systemically or locally. In this context, local anesthetic neural blockade with steroids and oral adjuvants deserves special attention, as useful, practicable and safe alternative which could be performed as an outpatient procedure.

Intractable pain consequent to post herpetic neuralgia can be safely and successfully managed with primary and secondary analgesics in combination with regional nerve blocks using steroids and local anaesthetics.

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