To assess the clinical effects of botulinum toxin type A injections in patients with refractory idiopathic trigeminal neuralgia.

Botulinum toxin type A (BTX-A) has been reported as being effective in the management of TN when injected sub-cutaneously along the trigeminal branches  or into trigger points  or below the zygomatic arch in doses ranging from 25 to 170 units.

We had 5 patients with refractory idiopathic TN, all female, with ages ranging from 27 – 61 years of age. The mean duration of pain was 98 months (8.1 years). All patients had increased sensitivity to touch over the maxillary region of the face, with disabling pain, despite receiving appropriate treatments for TN. 2 patients were considered candidates for decompression surgery, but preferred not to proceed.

A maximum of 35 units of BTX-A was injected intra-dermally with 10 units being injected just below the zygomatic arch and the other 25 units into painful facial triggers points in a grid-like fashion, approximately 2 cm apart. - "ZAPTed" injection protocol. 

The patients’ response to BTX-A was evaluated using the Numerical Rating Scale (NRS) and also the number of attacks per day, before and after BTX-A.

All patients obtained relief of pain and  reduced sensitivity to touch in the trigger points. The mean NRS was 8.6 at baseline and 1.0 at week 8. The mean number of paroxysms of pain reduced from 40 episodes of pain per day at baseline to 0.12 per day at week 8. The mean duration of effect was 16.8 weeks. Transient facial asymmetry was seen only in 1 patient after the first injection.

This study provides further support for the use of BTX-A in the treatment of TN. The effect can be long lasting and repeated, when required. The injections are well tolerated as the lower doses used.