Journal of Orofacial Sciences

ORIGINAL ARTICLE
Year
: 2016  |  Volume : 8  |  Issue : 2  |  Page : 86--91

Effectiveness of peripheral neurectomy in refractory cases of trigeminal neuralgia


Narayan Sharma Lamichhane1, Xiaoyan Du2, Shanchang Li1, Dhruba Chandra Poudel1,  
1 Department of Oral and Maxillofacial Surgery, School of Stomatology, Jiamusi University, Jiamusi, Heilongjiang, China
2 Department of Plastic and Reconstructive Surgery, School of Stomatology, Jiamusi University, Jiamusi, Heilongjiang, China

Correspondence Address:
Narayan Sharma Lamichhane
Department of Oral and Maxillofacial Surgery, School of Stomatology, Jiamusi University, Xuefu Street, Jiamusi 15400, Heilongjiang
China

Abstract

Context: Trigeminal neuralgia (TN) is a commonly diagnosed neurosensory disease of orofacial region involving the fifth cranial nerve. Patient refractory to pharmacotherapy or with clinical and/or laboratory side effects sufficient to demand drug cessation is subjected to surgical technique. Aims: The aim of this study is to investigate the efficacy of peripheral neurectomy in the management of refractory TN. Settings and Design: This retrospective study on forty patients refractory to carbamazepine was conducted in the department of oral and maxillofacial surgery in the Northeast part of China from September 2011 to September 2014. Patients and Methods: Patients treated with neurectomy were followed up at regular intervals to assess the duration of pain-free period, and the pain was assessed using visual analog scale and the success of the surgery was defined accordingly. Statistical Analysis Used: Descriptive statistical analysis was carried out using IBM SPSS-20. Results: The mean age of the patients was 67.92 years (46–86 years), with higher incidence in females (F:M = 1.6:1). The 3rd division of trigeminal nerve was most commonly affected by the disease. The right side was more common than the left side. Duration of postsurgical pain-free period varied from 12 to 36 months with mean pain-free duration of 23.25 months. Recurrent cases were treated with low dose of carbamazepine, and majority of them were relieved of symptoms. Conclusions: Peripheral neurectomy is a minimal invasive surgery; safe and effective for elderly patients, especially in rural areas where advanced neurosurgical facilities are not available and for those who are reluctant to major neurosurgical procedures.



How to cite this article:
Lamichhane NS, Du X, Li S, Poudel DC. Effectiveness of peripheral neurectomy in refractory cases of trigeminal neuralgia.J Orofac Sci 2016;8:86-91


How to cite this URL:
Lamichhane NS, Du X, Li S, Poudel DC. Effectiveness of peripheral neurectomy in refractory cases of trigeminal neuralgia. J Orofac Sci [serial online] 2016 [cited 2017 Apr 27 ];8:86-91
Available from: http://www.jofs.in/text.asp?2016/8/2/86/195908


Full Text

 Introduction



Trigeminal neuralgia (TN) is defined as “unilateral disorder characterized by brief electric shock-like pain, abrupt in onset and termination, and limited to the distribution of one or more divisions of the trigeminal nerve.”[1] Peripheral neurectomy is a simple, low-risk procedure that involves avulsion of the postganglionic portion of the branches of trigeminal nerve after it exits from cranium.

The aim of the study is to evaluate the efficacy of peripheral neurectomy as a surgical procedure in the treatment of refractory cases of TN, to evaluate the results thus obtained by the procedure and their recurrence in a period of 3-year follow-up.

 Materials and Methods



This was a retrospective study conducted in the department of oral and maxillofacial surgery, China, from September 2011 to September 2014. Forty patients refractory to carbamazepine were enrolled in the study. The diagnosis was based on a detailed history, clinical examination, and control of pain by carbamazepine. Orthopantomogram was taken for every patient to exclude any local pathology. All the patients were investigated preoperatively with computerized tomography scanning or magnetic resonance imaging (MRI) to rule out the underlying structural abnormalities such as tumors. Of the forty cases, MRI revealed compression of trigeminal nerve by superior cerebellar artery causing TN in three patients and anterior inferior cerebellar artery compressing trigeminal nerve in one patient.

We used International Headache Society (IHS) diagnostic criteria as well as Sweet's criteria for the diagnosis of classical TN. The IHS diagnostic criteria for the diagnosis of classical TN are as follows:

Paroxysmal attacks of pain lasting from a fraction of a second to 2 min, affecting one or more divisions of trigeminal nerve and fulfilling criteria B and C.Pain has at least one of the following characteristicsIntense, sharp, superficial, or stabbingPrecipitated from trigger areas or by trigger factorsAttacks are stereotyped in the individual patientThere is no clinically evident neurological deficitNot attributed to another disorder.[2]

Sweet's criteria have been commonly used worldwide for the diagnosis of TN. The criteria emphasize five major clinical features that in essence define the diagnosis of TN. They are described as follows:

The pain is paroxysmalThe pain may be provoked by light touch to the face (trigger zone)The pain is confined to trigeminal distributionThe pain is unilateralThe clinical sensory examination is normal.

We used the following criteria to differentiate classical TN from symptomatic trigeminal neuralgia, glossopharyngeal neuralgia, postherpetic neuralgia, sinusitis, etc.

The IHS diagnostic criteria for the diagnosis of symptomatic TN are as follows:

Paroxysmal attacks of pain lasting from a fraction of a second to 2 min, with or without persistence of aching between paroxysms, affecting one or more divisions of trigeminal nerve and fulfilling criteria B and CPain has at least one of the following characteristics Intense, sharp, superficial, or stabbingPrecipitated from trigger areas or by trigger factorsAttacks are stereotyped in the individuals patientA causative lesion, other than vascular compression, demonstrated by Special investigations and/or posterior fossa exploration.

IHS diagnostic criteria for classical glossopharyngeal neuralgia are as follows:

Paroxysmal attacks of facial pain lasting from a fraction of a second to 2 min and fulfilling criteria B and CPain has all the following characteristics:Unilateral locationDistribution within the posterior part of the tongue, tonsillar fossa, and pharynx or beneath the angle of the lower jaw and/or in the earSharp, stabbing, and severePrecipitated by swallowing, chewing, talking, coughing, and/or yawning Attacks are stereotyped in the individual patientThere is no clinically evident neurological deficitNot attributed to another disorder.

Postherpetic neuralgia

It is characterized by facial pain persisting or recurring ≥3 months after the onset of herpes zoster infection.

Diagnostic criteria

Head or facial pain in the distribution of a nerve or nerve division and fulfilling criteria C and DHerpetic eruption in the territory of the same nervePain preceded herpetic eruption by <7 daysPain persists after 3 months.

Postherpetic neuralgia is more often a sequel of herpes zoster as age advances, afflicting 50% of patients contracting zoster over the age of 60 years. Hypoesthesia or hyperalgesia and/or allodynia are usually present in the territory involved.

Sinusitis

An important diagnostic characteristic is that the pain is not located in one particular tooth, but tends to involve all molar and premolar teeth in that quadrant. The teeth may exhibit percussion sensitivity and often patients will complain of chewing discomfort and cold sensitivity. In addition, when the head is lowered to a level below the knees (a maneuver that results in gravitational shifting of fluid in the sinus), the pain is exacerbated. This may worsen during pregnancy and the patients tend to have recurrent episodes, especially in the spring and autumn seasons. These patients may complain of exaggerated pain upon changes in barometric pressure; thus high altitudes and flying will exacerbate their pain. There is also infraorbital tenderness upon palpation over the affected sinus. A Waters' radiograph may show an air–fluid level or thickened mucosa in the sinus. Other diagnostic approaches include the use of transillumination.

Okeson and Bell summarized the clinical characteristics of sinus or nasal mucosal toothache as follows:

Pressure below the eyesIncreased pain with lowering the headIncreased pain with pressure over the involved sinusLocal anesthesia of the tooth does not eliminate the painDiagnosis confirmed when air/fluid level seen on appropriate imaging studies.[2]

The branch of the nerve involved in classical TN was identified according to the site of the pain and confirmed with diagnostic block with 2% lignocaine with adrenaline at 1:200,000. All the patients who had become refractory to carbamazepine were considered for surgical treatment. The follow-up period covered by this study ranged from 1 to 3 years. The factors analyzed were demographic details of the patients (age and sex), side of involvement, branch of nerve involvement, procedure used, postoperative complications, and any additional procedures used in cases of recurrences.

The study was approved by the Institutional Ethical Board of School of Clinical Stomatology, China.

Inclusion criteria

The inclusion criteria were as follows:

Patients with persistence of pain after conservative treatment with carbamazepine (refractory to medical therapy)Intolerance to carbamazepine because of its side effectElderly patients unfit for major surgical procedures and patients who were reluctant for major neurosurgical treatment.

Exclusion criteria

The exclusion criteria were as follows:

Patients below 40 yearsPreviously treated cases of neurectomyPatients having contraindications for local anesthesia and general anesthesiaCases with atypical presentation such as bilateral involvement, uncommon distribution, and longer than usual painInsufficient records and/or follow-upPatients unwilling to give consent for the study.

Pain was assessed using visual analog scale (VAS), and success of the surgery was defined accordingly:

Excellent: total loss of pain, postsurgery carbamazepine not requiredGood: recurrence of mild-to-moderate pain, relieved with modest dose of carbamazepinePoor: no significant pain relief even after neurectomy.

Surgical technique

Infraorbital neurectomy

Access to infraorbital nerve was gained through a maxillary vestibular approach. Infraorbital foramen was visualized, and infraorbital nerve and its peripheral branches were identified. Avulsion of the nerve was then performed from the soft tissues and from infraorbital canal by reeling on a hemostat. The remnants of the nerve were cauterized deep in the foramen [Figure 1].{Figure 1}

Inferior alveolar neurectomy

A linear incision extending lingually and buccally was made along the anterior border of the ascending ramus, which was then deepened on its medial aspect by means of a blunt and sharp dissection. The temporalis and medial pterygoid muscles were split, and the nerve was located. Two heavy black linen threads were then looped around the nerve using nerve hook and then divided between the two threads. This was done as high as possible and the distal end was avulsed by reeling on hemostat. The remnants of the nerve were cauterized deep in the foramen [Figure 2].{Figure 2}

Dr. Ginwalla's incision is usually preferred for inferior alveolar neurectomy, in which an inverted Y-shaped incision is made along the anterior border of ascending ramus, but we preferred a linear incision along the anterior border and performed subsequent dissection to expose the inferior alveolar neurovascular bundle.[3] The linear incision was sufficient enough to provide access for the neurectomy procedure.

Supraorbital neurectomy

It was approached extraorally through the upper eyebrow incision; the nerve was identified and avulsed by reeling on a hemostat. The remnants of the nerve were cauterized. Double layer closure was done with 3-0 vicryl and 3-0 ethilon [Figure 3].{Figure 3}

Antibiotics and anti-inflammatory drugs were prescribed postoperatively, and the patients were followed up for 3 years.

Descriptive statistical analysis was carried out by using IBM SPSS software package version 20 (IBM Corporation, USA).

 Results



The study was conducted on forty patients who fulfilled the criteria. The age of the patients ranged from 46 to 86 years with a mean of 67.92 years (standard deviation: 10.39) at the time of presentation. Fifth and sixth decades of age were the common age group. Of the total patients, 25 (62.5%) were females and 15 (37.5%) were males (F:M = 1.6:1). The third division of trigeminal nerve (mandibular division/inferior alveolar nerve) was most commonly affected by the disease (20 patients [50%]). The second division (maxillary division/infraorbital nerve) was involved in 14 patients (35%). The second and the third divisions were involved in four patients (10%) and the first division (supraorbital nerve) was affected in two patients (5%). The right side of the face was affected in 27 patients (67.5%) whereas the left side in 13 patients (32.5%). Bilateral involvement was seen in none.

The mean follow-up period was 24.75 months (12–36 months). Following neurectomy, pain was relieved in all cases. The patients were followed up on 7th postsurgical day and thereafter, reviewed at 3 months, 6 months, 1 year, 1.5 years, 2 years, 3 years, or as soon as pain recurred. The pain-free period was thus evaluated. Postsurgical pain relief varied from 12 to 36 months. The assessment of pain was done by VAS.

Twenty-six patients (65%) had excellent pain relief lasting from 12 to 36 months without any medications as shown in [Table 1]. In ten patients (25%), there was recurrence of pain after 14–31 months of the peripheral neurectomy. These patients were again prescribed tablet carbamazepine but this time at a lower dose of 200 mg 12 hourly. Interestingly, those refractory to even higher doses of carbamazepine before neurectomy were relieved of symptoms at a low dose of carbamazepine in cases of pain recurrence following neurectomy. Four patients (10%) had poor pain relief lasting from 14 to 26 months. They did not respond even to higher doses of carbamazepine. Second neurectomy was done on two patients to relief the pain and the remaining two patients were referred to neurosurgeons for further surgical interventions.{Table 1}

The average pain-free period after neurectomy was 23.25 months (12–36 months). The earliest pain recurrence following neurectomy was observed on 14th month. We could not correlate any systemic illnesses to be associated with recurrences among the forty patients we studied. Some patients with systemic illnesses such as diabetes mellitus, hypertension, and cardiovascular diseases before neurectomy were having similar recurrences with patients without any systemic diseases.

In fact, 43 patients were evaluated for pain-free period, but one patient passed away after 13 months of treatment from other causes and two patients did not maintain regular follow-up, and they were excluded from the study.

There were no intraoperative complications. None of the patients had postoperative infections and suture dehiscence. There was some facial swelling and bruising in early postoperative period and expected loss of sensation in the appropriate distribution of trigeminal nerve.

 Discussion



Peripheral neurectomy was practiced for the first time in the 18th century with limited success. This procedure provides exact, complete, and long-lasting effect. It can be done on supraorbital, supratrochlear, infratrochlear, lacrimal nerves, infraorbital nerve, and inferior alveolar, lingual, and mental nerves. Neurectomy of the peripheral branches of trigeminal nerve is the simplest, safest, and minimally invasive surgical method that can be carried out as an outpatient procedure under local anesthesia.

Most of the studies done for neurectomy were published 20–50 years ago. In 1965, Quinn and Weil reported a retrospective case series of 63 patients with 112 neurectomies.[4] Pain relief period of 24–32 months was reported within a follow-up period of 0–9 years. In our study, the mean pain-free period was 23.25 months, which is not so varied with the above findings.

We found an average pain relief of 23.25 months in contrast to the study of Grantham and Segerberg with an average pain relief period of 33.2 months in a case series of 55 patients who had undergone 55 neurectomies with follow-up for 5 months to 8 years.[5] The difference may be attributed by the fact that their study reported 33.2-month pain relief period just for supraorbital and infraorbital nerves, but the findings of our study are on an average for all the three divisions of trigeminal nerve.

There was a difference of 3.25 month pain-free period between our findings and Freemont's study. Freemont studied on 146 patients, of whom 26 patients underwent neurectomy and noted an average of 26.5 months of pain-free period following a single peripheral neurectomy.[6] The difference may be attributed to the use of fatty tissue for packing the foramen following neurectomy in his study. In our study, the remnants of the nerve were just cauterized deep in the foramen. Our finding of patients with recurrence of pain being responsive to low doses of carbamazepine is consistent with Freemont's finding.

In our study, we found 26 (65%) patients having excellent pain relief from 12 to 36 months and 14 patients (35%) having recurrence from 14 to 31 months which is consistent with the previous study by Murali and Rovit.[7]

Our finding of 65% of the patients having excellent pain relief is comparable to Syed Amjad Shah's study on fifty patients with 70% of the patients having excellent pain relief lasting for 2–5 years without any medications. Similarly, 10% of the patients in our study had poor pain relief from 13 to 30 months which is consistent with the finding of the above study of having 12% recurrence uncontrolled even with medication.[8]

The pain-free duration of 12–36 months of our study following the first neurectomy contradicts with Cerovic et al's. finding of 12–18 months.[9] They reported that after the 1st operation on infraorbital nerve, the recurrence of pain was seen in 41% of the patients. After the 2nd operation, 35% of the cases had recurrence between 9 and 12 months. Subsequently, recurrence was seen in 44% of the cases after the third surgery with pain-free period no longer than 12 months. The authors concluded that the remission time after repetitive neurectomy decreases, hence there is no point in repeating the surgery on the same neural branch more than three times.

Comparable with the study of Agrawal and Kambalimath on 28 patients, our study also found low doses of tablet carbamazepine to be effective in patients having recurrence of pain following neurectomy.[3]

Neurectomies followed by obturation of the foramen with fat,[6] titanium screws,[10] gold foils,[11] and silicone [12] are also tried with variable success rates. A recent comparative study was done by Fareedi Mukram Ali and his group. Postsurgical pain relief varied between 15 months and 24 months in cases without placing stainless screws in the foramen. Those cases in which peripheral neurectomy was done along with placement of stainless screws in the foramina, none of the patients had painful symptoms even after 2 years of minimum follow-up.[12]

In our study, neuralgic pain attacks were observed in two patients along the same branch of the nerve after neurectomy in first 48 h but interestingly disappeared afterward. The similar finding was observed by Shah et al. in their study. In 1886, Geo R Flower pointed in his article that in cases of peripheral origin, after neurectomy, the pain would sometimes persist for few days and then gradually disappear.[13] This is explained by the fact that the morbid condition also involved some communicating or anastomosing twigs. As the process of degeneration goes on in these twigs, after resection, the symptoms slack off and finally cease together. However, further study is required to find out the exact cause.

The enigma regarding the etiology of TN still continues with the recurrence of pain following surgical procedures. The possible causes of recurrence of pain following neurectomy are as follows: (1) onset of symptoms in other branches of the same division of trigeminal nerve,[14] (2) from the intact collateral branches or the main ascending trunk remaining after the neurectomy [11] (3) neuroma formation in the excised nerve,[15] (4) and demyelination and central sensitization.[16] Demyelination (due to vascular compression, multiple sclerosis) leads to generation of ectopic impulses from demyelinated axons. There is sensitization of nociceptive nerve fibers due to an upregulation of sodium channels and adrenergic and nicotinic cholinergic receptors that result in a hyperexcitability of the involved nerve. In addition, ephaptic conduction or “cross-talk” between adjacent nerve fibers can take place leading to abnormal sensitivity and spontaneous activity of axons in the nerve, i.e., activity spreads from Aβ touch afferents to nociceptors which accounts for precipitation of attacks of neuralgia by light tactile stimulation of facial trigger zones. As ectopic peripheral nerve input continues, changes in neural structures involved in pain perception, i.e., the dorsal root ganglion, the dorsal horn of the spinal cord, thalamus, and sensory cortex start to take place. This results in an increased excitability of neurons in adjacent spinal segments and cortical areas, also called “central sensitization.”

 Conclusion



TN is the most common neuralgic cause of facial pain. Surgical treatment should only be considered if patients become refractory to drug therapy or adverse effect sufficient to mandate drug cessation. Peripheral neurectomy is a minimal invasive form of surgery, safe and effective for elderly patients, for those living in rural places who cannot avail major neurosurgical facilities and for those patients who are reluctant to major neurosurgical procedures. Although recurrence is associated with a majority of cases, peripheral neurectomy seems to be promising for a considerable period of time with minimal mortality, morbidity, and postoperative complications.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

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