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CLINICAL REVIEW: Luke Bennetto, Nikunj K Patel, and Geraint Fuller Trigeminal neuralgia and its management BMJ 2007; 334: 201-205 [Full text]

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Peripheral Surgery is still an imortant option in the management of Trigeminal Neuralgia

Niall M H McLeod   (31 January 2007)

High quality studies are required to verify the role of all surgical treatments in trigeminal neuralgia

Luke Bennetto, Nikunj Patel and Geraint Fuller   (11 February 2007)

Peripheral Surgery is still an imortant option in the management of Trigeminal Neuralgia 31 January 2007
Niall M H McLeod, SpR Oral & Maxillofacial Surgery Queen Alexandra Hospital, Portsmouth Send response to journal: Re: Peripheral Surgery is still an imortant option in the management of Trigeminal Neuralgia	It is disappointing that Bennetto et al have completely ignored the role of peripheral surgery in their otherwise concise review.(1) Whilst it is entirely appropriate to manage most patients initially with medication, there is a significant cohort of patients do not get satisfactory pain relief or are unable to tolerate medical management. Some of these patients will be suitable for neurosurgical options such as Microvascular Decompression (MVD), however there remains a significant number of patients who cannot tolerate medication and are unsuitable for or unwilling to consider MVD. These patients may undergo neuroablative procedures at the Gasserian ganglion or in the posterior cranial fossa. These often offer temporary pain relief (potentially for 5 years or more) but still carry some risks.(2) Another treatment option is so called peripheral surgery which involves neuroablative procedures where the peripheral branches of the trigeminal nerve become more accessible, for example at the infra-orbital or mental foramina. Various techniques are described the most common of which are injection of alcohol or glycerol,(3) cryotherapy(4) and neurectomy.(5) All have minimal risks and complications, and their duration of effect ranges from 9-24 months. These procedures are mostly carried out in the United Kingdom by Oral & Maxillofacial Surgeons. Most units offer to see patients within 48 hours and are often able to offer peripheral surgical treatment either immediately or within a few days, due to their relative ease of administration and need for little specialist equipment. Peripheral surgery may therefore not only be used for patients who are unable to have other treatments but also those who are waiting for MVD. There is no evidence that alcohol injections impede the result of neurosurgical treatments.(6) With regards to medical management, Oxcarbazepine has been available as an alternative to Carbamazepine for many years and there is reasonable evidence to support its use. Its principal advantage is that it does not cause liver toxicity and therefore can be used where patients are unable to tolerate Carbamazepine due to liver enzyme derangement. Its other side effects are similar and limit its use otherwise in patients who cannot tolerate Carbamazepine.(7) 1. Bennetto L, Patel NK, Fuller G. Trigeminal Neuralgia and its management. BMJ 2007; 334: 201-5 2. Zakrzewska JM. Trigeminal Neuralgia. In: Zakrzewska JM, Harrison SD, ed.: Assessment and management of orofacial pain. London: Elsevier, 2002: 267-370. 3. Fardy MJ, Zakrzewska JM, Patton DW. Peripheral Surgical Techniques for the management of trigeminal neuralgia – Alcohol and Glycerol injection. Acta Neurochir (Wien) 1994: 129: 181-185. 4. Zakrzewska JM , Nally FF. The role of cryotherapy (cryoanalgesia) in the management of paroxysmal trigeminal neuralgia: a six year experience. Br J Oral Maxillofac Surg 1988: 26: 18-25. 5. Oturai AB, Jensen K, Eriksen J, Madsen F. Neurosurgery for Trigeminal Neuralgia: Comparison of Alcohol Block, Neurectomy and Radiofrequency Coagulation. Clin J Pain 1996: 12:311-315. 6. McLeod NMH, Patton DW. The role of peripheral alcohol blocks in the management of trigeminal neuralgia. Oral Surg Oral Med Oral Path Oral Rad Endo: In press. 7. Zakrzewska JM, Patsalos PN. Oxcarbazepine – a new drug in the management of trigeminal neuralgia. J Neurol Neurosurg Psychiatry 1989: 52: 472-476. Competing interests: None declared
High quality studies are required to verify the role of all surgical treatments in trigeminal neuralgia 11 February 2007
Luke Bennetto, Neurology SpR Frenchay Hospital, Bristol, BS16 1LE, Nikunj Patel and Geraint Fuller Send response to journal: Re: High quality studies are required to verify the role of all surgical treatments in trigeminal neuralgia	We read McLeod’s response with interest and would like to thank him for bringing the role of peripheral neuro-ablative procedures in trigeminal neuralgia management to the attention of readers. Peripheral neuro-ablative procedures lesion the trigeminal nerve distal to the gasserian ganglion rather than the ganglion lesions we discussed in our review. In the first instance it is probably worth sharing our editorial brief with the reader – this review was aimed at the non-specialist and there were significant restrictions on word counts and references. Whilst further detail is available on the web version this inevitably cannot cover every aspect of trigeminal neuralgia and McLeod is correct in identifying the omission of peripheral neuro-ablative procedures. The evidence suggests that invasive ablative procedures which target the gasserian ganglion result in pain freedom at 12 months in 70-87%(1) of patients whereas ablation of the peripheral branches of the trigeminal nerve typically achieves pain freedom at 12 months in 30-40% of patients(2;3). The natural history of trigeminal neuralgia is unknown and it is therefore difficult to have complete confidence in an invasive procedure, which is not without risk(4) and likely to have a powerful placebo effect(5), without the support of randomised sham controlled studies. Whilst this is also true of all the surgical treatments of trigeminal neuralgia the relative inefficacy of peripheral surgery compared to gasserian lesions on current evidence makes distinction from placebo less certain. This should not be read as an attempt to dismiss the potential role of peripheral surgery but rather to encourage properly controlled studies of all the surgical treatments of trigeminal neuralgia so that in future we can more confidently answer the question: ‘What would you have done doctor?’ Reference List 1. Bennetto L, Patel NK, Fuller G. Trigeminal neuralgia and its management. BMJ 2007;334:201-5. 2. Zakrzewska JM. Cryotherapy in the management of paroxysmal trigeminal neuralgia. J Neurol Neurosurg Psychiatry 1987;50:485-7. 3. Pradel W, Hlawitschka M, Eckelt U, Herzog R, Koch K. Cryosurgical treatment of genuine trigeminal neuralgia. Br.J Oral Maxillofac.Surg. 2002;40:244-7. 4. Willy PJ, McArdle P, Peters WJ. Surgical emphysema and Collet- Sicard syndrome after cryoblockade of the inferior alveolar nerve. Br.J Oral Maxillofac.Surg. 2003;41:190-2. 5. Brown WA. The placebo effect. Sci Am. 1998;278:90-5. Competing interests: None declared