|Year : 2022 | Volume
| Issue : 3 | Page : 843--844
Secondary Trigeminal Neuralgia- Surgery vs. Radiosurgery: Which is better?
P Sarat Chandra
Professor, Department of Neurosurgery, All India Institute of Medical Sciences (AIIMS), New Delhi, India
P Sarat Chandra
Department of Neurosurgery, All India Institute of Medical Sciences (AIIMS), New Delhi
|How to cite this article:|
Chandra P S. Secondary Trigeminal Neuralgia- Surgery vs. Radiosurgery: Which is better?.Neurol India 2022;70:843-844
|How to cite this URL:|
Chandra P S. Secondary Trigeminal Neuralgia- Surgery vs. Radiosurgery: Which is better?. Neurol India [serial online] 2022 [cited 2022 Aug 17 ];70:843-844
Available from: https://www.neurologyindia.com/text.asp?2022/70/3/843/349723
Trigeminal neuralgia (TN), is the most common form of severe facial pain. It may often be confused with other conditions. It has been described as one of the most painful conditions. The lifetime prevalence for TN is approximately 0.3%, and other facial pains are about 0.03%. TN is 15–20 times more common in persons with multiple sclerosis. While TN is often a straightforward diagnosis, opera good is essential, and not uncommonly, it may be confused with other conditions. One study found that migraine headache occurs in almost 60% of their patients, trigeminal autonomic cephalalgias (TAC) in approximately 12%, and of those with facial pain, almost nearly all had persistent idiopathic facial pain (PIFP). It is thus essential to think of concomitant conditions while considering TN. There are three major types of the non-odontogenic head or facial pain to be considered as a differential diagnosis. These include (1) trigeminal autonomic cephalalgias (TAC), e.g., Cluster headaches, (2) post-herpetic neuralgia (PHN), and (3) persistent idiopathic facial pain (PFIP). Myofascial pain in head and neck muscles could be a potential explanation for a subset of PIFP, as well as an exacerbating factor for TN. All these have to be ruled out while diagnosing TN or maybe even considered co-existing with TN.
Pharmacotherapy is the initial treatment of choice almost always. The goal is to reduce the hyperexcitable bursts of nerve discharges. Carbamazepine is generally considered the drug of choice. It is effective in 60–100% of cases, at least for a time, though the failure rate of long-term treatment can be as high as 50%, Furthermore, there are significant adverse side effects associated with carbamazepine. Oxcarbazepine, considered to have fewer side effects than carbamazepine, is often used instead of carbamazepine, although there is little experimental data as opposed to clinical experience to support its use. These drugs target voltage-gated sodium channels. There is low-quality evidence for the benefit of other anticonvulsant drugs such as lamotrigine and gabapentin. Newer pharmaceuticals, such as eslicarbazepine, an active metabolite of oxcarbazepine, and a Nav1.7 channel blocker vixotrigine, are being evaluated as treatments.
Several surgical therapeutic options are available depending on their availability in that center and the preference and expertise of the treating physician. These include interventions such as percutaneous rhizotomy, radiofrequency thermocoagulation, balloon compression, gamma knife radiosurgery, and microvascular decompression. In addition, Botulinum toxin type A (BTxA) has a beneficial role in the treatment not only for TN but also for other types of neuropathic pains. It has both antinociceptive and anti-inflammatory activity, the two mechanisms being dissociated. Botulinum toxin A acts at both peripheral and central sites. Peripherally, it blocks the docking of intraneuronal vesicles to the inner membrane of the nerve terminal, inhibiting the release of neuropeptides and neurotransmitters. A non-randomized, uncontrolled, unblinded study of 27 subjects evaluated the effect of BTxA over six months. A total of 88.9% had pain relief by more than 50% at the end of 6 months. About 50% required a second injection and 25% a third injection. Overall, BTxA offers an effective form of treatment for those individuals for whom oral medication such as oxcarbazepine has failed or for whom interventional therapies such as peripheral nerve ablations or microvascular decompression are not suitable.
In the current literature, there is a knowledge gap regarding the efficacy of radiosurgery vs. surgery for secondary TN due to tumors like meningiomas or vestibular neurinomas. A recently performed systemic meta-analysis identified 330 potential studies regarding TN due to secondary causes treated with stereotactic radiosurgery (SRS). Of these, 13 studies were found suitable for the meta-analysis. They found that about 50% (range 36-65%) of the patients had complete relief of pain and were medication-free with SRS and a lesser degree of pain control was a reported in about 41% (range 29-52%) of the patients (Barrow neurological institute- BNI pain intensity score of 1, see footnote). These included patients having some to occasional pain requiring no or adequate medication (BNI 1-III). The pathologies causing TN included meningiomas, vestibular neurinomas, epidermoid, Trigeminal schwannoma, arteriovenous malformations, and others. Overall, complications were rare. The most common complication was facial numbness beside numbness, transient tinnitus, and diminished hearing (in the context of vestibular neurinomas). Interestingly, there were no cases reported of corneal anesthesia or anesthesia Dolorosa. Other complications included balance problems, masseter weakness, abducens palsy, and ipsilateral hemispheric stroke.
Regarding the comparison of MVD vs. radiosurgery for treating TN, a systematic review of studies published between 2000-2015 found better quality of life (QOL) scores for patients undergoing MVD compared to radiosurgery at a seven-year follow up. In addition, those undergoing MVD had a significantly higher rate of pain relief and a considerably lower rate of complications and recurrence. Another systematic meta-analysis performed a year later concluded that MVD is more efficacious compared to gamma knife. However, the dilemma regarding treatment choice remains, especially for patients, like the elderly and those in whom no vascular compression has been found during surgery.
Further studies are needed to elucidate the unequivocal treatment plan under these circumstances. One study compared the cost-effectiveness of radiosurgery vs. microvascular decompression (MVD) in the US health care system and found MVD to be the most cost-effective. The current paper published in this issue had a cohort of 47 patients with small petrous apex meningiomas split into equal proportions of patients undergoing SRS and surgery. The patients included in this study included those with <3cm size of tumors, tried at least two medications, pathologically proven meningioma for the surgically resected group, and imaging characteristics for patients undergoing gamma knife. The patients undergoing surgery had a lower BNI pain intensity score than those who underwent SRS. Overall, those undergoing surgery had good BNI scores (I-III) compared to those who underwent SRS. Postoperative paraesthesia showed no significant difference between both groups. In terms of local tumor control, this was equal between both groups. Surgery was more cost-effective than SRS in this study. Complications, however, were higher in the surgery group (13% vs. 9%). There has been only one study published earlier comparing SRS with surgery for small petroclival meningiomas. They too concluded that surgery could be more effective than gamma knife surgery in providing prompt, medication-free pain relief from TN for small petroclival meningiomas. The main shortcoming of the current study is the short follow-up. However, overall, the study demonstrates that surgery is more efficacious for small petroclival meningiomas than SRS. It is also more cost-effective. But again, the decision to provide SRS depends on the patient's choice and the presence of co-morbidities that may preclude surgery. A more extensive study is warranted.
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