Comparative Efficacy of Carbamazepine Versus Oxcarbazepine in Treatment of Trigeminal Neuralgia- a Randomized Controlled Clinical Study

Trigeminal neuralgia is a neuropathic facial pain condition which is characterised by unilateral paroxysmal pain which is excruciating, short lasting in the distribution territory of trigeminal nerve.(1) Trigeminal neuralgia is oro-facial pain restricted to one or more divisions of the trigeminal nerve. With the exception of Trigeminal Neuralgia caused by Multiple sclerosis, the pain affects one side of the face. It is abrupt in onset and typically lasts only a few seconds (2 min at maximum).Patients may report their pain as arising spontaneously, but these pain paroxysms can always be triggered by innocuous mechanical stimuli or movements. Patients usually do not experience pain between paroxysms. If they do report additional continuous pain, in the same distribution and in the same periods as the paroxysmal pain, they are considered to have Trigeminal Neuralgia with continuous pain. (IASP)(1) Trigeminal neuralgia is mainly classified into three diagnostic categories i.e. Classical, Secondary and Idiopathic. This classification is mainly based on the etiology & pain characteristics. The etiology of Trigeminal Neuralgia is not well understood, but various theories such as Compression of sensory root of trigeminal nerve by arteries & bony exostoses.(4) ,focal demyelination of trigeminal afferents near the entry of the trigeminal root into pons(2)and alteration in the central neural function followed by injury to peripheral nerves (4) are widely accepted.

Trigeminal Neuralgia has a profound effect on quality of life of the patient & expenditure on health (4). Due to the severe intensity of pain, patients avoid touching face, washing face, thus making patient's life disturbing & miserable. Even after so many years of research, it is still a challenge to treat patients suffering from Trigeminal Neuralgia. Treatment can be sub- divided into pharmacological & invasive therapies .

The pharmacological therapy include drugs such as carbamazepine ( 200-1200mg) , oxcarbazepine (300-1800mg) , lamotrigine, Gabapentin , baclofen, eslicarbazepine, sumatriptan, vixotrigine. The pre- surgical procedures like botulinium toxin A & intranasal non-inhaled CO2 have also been sporadically used (1).

A review study discussing the pharmacological options to treat trigeminal neuralgia concluded that carbamazepine & oxcarbazepine are the first choice of drugs(1). Oxcarbazepine showed equal efficacy in reducing pain attacks with better tolerability & less side effects (1) .

A recently conducted study found that carbamazepine is associated with serious side effects including CNS disturbances, somnolence, unbalance, thrombocytopenia, increase level of transaminases while OXC showed similar efficacy with less side effects. CNS disturbances encountered in patients on CBZ were triple to those on OXC & withdrawal from the treatment was also more in patients on CBZ(27%) than on OXC (18%)(12).