Therapeutic Failure in Trigeminal Neuralgia: from a Clarification of Trigeminal Nerve Somatotopy to a Targeted Partial Sensory Rhizotomy

doi:10.1016/j.wneu.2018.05.211

World Neurosurgery

Volume 117, September 2018, Pages e138-e145

https://doi.org/10.1016/j.wneu.2018.05.211 Get rights and content

Highlights

•
We refine the somatotopy of CNV in juxtapontine portion after an extensive literature review.
•
We bring new anatomic landmarks for targeted partial sensory rhizothomy (TPSR).
•
In this retrospective study of 22 patients, pain relief was achieved in 100% and complete in 86.4% of the patients.
•
TPSR is an interesting alternative to other destructive procedures for pharmacoresistant TN without vascular compression.

Background

Trigeminal neuralgia (TN) is a severe unilateral facial pain involving 1 or more branches of the trigeminal nerve (CNV). Microvascular decompression is a standard curative treatment of pharmacoresistant classic TN. Alternative procedures used for secondary or idiopathic TN usually lead to a high rate of pain recurrence and sensitive deficits. Partial sensory rhizotomy (PSR) is one of these ablative procedures. However, the lack of anatomic knowledge about the somatotopy of CNV lead to variable results in pain relief and hypoesthesia.

Objective

To refine the somatotopy of CNV and bring new anatomic landmarks for PSR, studying a cohort of patients treated by a targeted PSR (TPSR).

Methods

Retrospective and consecutive cases of adult patients treated in our institution between March 2000 and June 2015 for pharmacoresistant TN without vascular compression were collected. Our surgical procedure was performed using a precision map of the somatotopy of CNV. We compared our results with other surgical and nonsurgical therapies.

Results

Twenty-two patients had undergone TPSR. Fourteen had an idiopathic TN without compression of the nerve root, 6 had a secondary TN caused by multiple sclerosis, and 2 had a trigeminal conflict by inoperable tumor. Complete pain relief was achieved in 86.4% of the patients. Postoperative hypoesthesia was partial and focalized (22.7%). TN recurrence rate at 5 years was 31.5% (standard deviation, 10.9%).

Conclusions

We clarified the functional somatotopy of CNV in its juxtapontine portion. TPSR is an interesting alternative to other ablative procedures to treat pharmacoresistant TN without vascular compression.

Introduction

Trigeminal neuralgia (TN) is a severe unilateral facial pain involving 1 or more branches of the fifth cranial nerve (CNV), often provoked by stimuli on the face such as light touch, eating, talking, or shaving.¹ The pain is characterized by electric shock–like paroxysms, which makes the TN one of the worst neuropathic pains, leading to significant social disability.1, 2 The estimated annual incidence of TN is 12.6/100,000.² Three categories can be distinguished³: classic TN, consecutive to vascular compression of CNV at the root entry zone; secondary TN, consecutive to several diseases such as multiple sclerosis, pons infarction, or masses compressing CNV in the cerebellopontine angle; and idiopathic TN, in which the cause is unknown.

Although most of the time pain relief is obtained with medical treatment by carbamazepine or other antiepileptic drugs, some patients require invasive procedures either when TN becomes pharmacoresistant or when drug side effects are too debilitating.⁴ Surgical treatment can be divided into nonablative and ablative procedures. Microvascular decompression (MVD) is the only nonablative surgical procedure. This procedure usually offers the best rates of long-term complete pain relief without hypoesthesia.4, 5 However, this technique is proposed only to patients with classic TN.6, 7, 8, 9

Ablative procedures, such as radiofrequency thermal rhizotomy, retrogasserian glycerol rhizotomy, trigeminal balloon compression, partial sensory rhizotomy (PSR), and sterotactic radiosurgery, are usually proposed to patients with secondary or idiopathic TN. However, these procedures produce a high rate of facial sensory loss, in addition to a trigeminal motor dysfunction and incomplete pain relief with pain recurrence.4, 6, 7

PSR has been well known since the first operation by Dandy in 1929.¹⁰ However, the technical heterogeneity of this procedure (i.e., from one procedure to another, the rhizotomy of the pars major of CNV can involve from 10% to 100% of the nerve and is performed either within the juxtapontine portion or not) and the lack of anatomic knowledge about the somatotopy of CNV lead to variable results in pain relief and hypoesthesia, as well as to a higher risk of impaired corneal reflex. The hazardous results of this technique explain why it was gradually abandoned.

The most recent anatomic studies regarding the somatotopy of CNV date from 1971. In our view, the functional nerve somatotopy previously described is not entirely accurate and could be clarified. Here, we propose to refine the somatotopy of CNV in its juxtapontine portion, based on an extensive review of the literature by focusing on electrophysiologic data, anatomic data, and surgical outcomes.

We developed a revisited procedure called targeted PSR (TPSR) (ventrolateral two thirds rhizotomy of the pars major in its juxtapontine portion) according to new precisions of the somatotopy of CNV. We then present a retrospective series of 22 patients with secondary or idiopathic TN treated by TPSR from March 2000 to June 2015. We then discuss the role of the somatotopic organization of sensory fibers in the juxtapontine trigeminal root to explain our results.

Section snippets

Data Collection

We retrospectively collected, between March 2000 and June 2015, imaging and medical data of patients meeting the following criteria: 1) TN diagnosed according to the new classification³; 2) severe pharmacoresistant pain; 3) no vascular conflict characterized on magnetic resonance imaging (MRI); 4) no impairment of the proprioceptive facial sensibility before surgery; and 5) absent or moderate pain in V1 territory.

Surgical Procedure

The patients were placed under general anesthesia and in the park-bench position.

Results

A total of 155 patients were surgically treated for TN in our institution from March 2000 to June 2015. A total of 133 patients (85.8%) had undergone MVD. Twenty-two patients (14.2%) fitting the criteria described earlier had undergone TPSR. The mean follow-up time was 67.3 months (range 6–252 months). Among these 22 patients, 3 had died from extraneurologic causes, and 2 were no longer to be found after a mean follow-up of 52 months from the surgical procedure. The area of numbness was

Discussion

Our study, based on a standardized and revisited procedure (ventrolateral two thirds rhizotomy of the pars major in juxtapontine portion) seems to be a privileged alternative to treat pharmacoresistant TN with no vascular compression. Unlike MVD, which remains the preferred treatment for TN with neurovascular compression because of its safe and effective treatment with a high rate of long-term success,4, 12 pharmacoresistant TN with no vascular compression is treated with numerous invasive

Conclusions

TN is one of the worst neuropathic pains, leading to significant social disability. Such patients should never be in a therapeutic impasse. We propose a new insight into the somatotopy of the trigeminal nerve in its juxtapontine portion, based on our results and on an extensive literature review of electrophysiologic, anatomic, and historic surgical outcome.

As a result, the section of the ventrolateral two thirds of the pars major of the trigeminal nerve at the pons provides excellent outcomes

Acknowledgments

We would like to thank Prof. Marc Sindou for his valuable assistance and his personal experience feedback on trigeminal rhizotomy.

References (30)

J.S.H.A. Koopman et al.
A nationwide study of three invasive treatments for trigeminal neuralgia
Pain
(2011)
M. López de Armentia et al.
Electrophysiological properties of identified trigeminal ganglion neurons innervating the cornea of the mouse
Neuroscience
(2000)
A. Nakamura et al.
Morphological and immunohistochemical characterization of the trigeminal ganglion neurons innervating the cornea and upper eyelid of the rat
J Chem Neuroanat
(2007)
G.R. Nugent
Patient reports of satisfaction after microvascular decompression and partial sensory rhizotomy for trigeminal neuralgia
Neurosurgery
(2006)
G. Cruccu et al.
Trigeminal neuralgia: New classification and diagnostic grading for practice and research
Neurology
(2016)
F.G. Barker et al.
The long-term outcome of microvascular decompression for trigeminal neuralgia
N Engl J Med
(1996)
P.J. Jannetta
Neurovascular compression in cranial nerve and systemic disease
Ann Surg
(1980)
B.C. Lopez et al.
Systematic review of ablative neurosurgical techniques for the treatment of trigeminal neuralgia
Neurosurgery
(2004)
B.C. Lopez et al.
Stereotactic radiosurgery for primary trigeminal neuralgia: state of the evidence and recommendations for future reports
J Neurol Neurosurg Psychiatry
(2004)
J.S. Cheng et al.
A review of percutaneous treatments for trigeminal neuralgia
Neurosurgery
(2014)

G. Broggi et al.

Microvascular decompression for trigeminal neuralgia: comments on a series of 250 cases, including 10 patients with multiple sclerosis

J Neurol Neurosurg Psychiatry

(2000)

W.E. Dandy

An operation for the cure of tic douloureux. Partial section of the sensory root at the pons

Arch Surg

(1929)

R.H. Dworkin et al.

Advances in neuropathic pain: diagnosis, mechanisms, and treatment recommendations

Arch Neurol

(2003)

M. Sindou

Trigeminal neuralgia: a plea for microvascular decompression as the first surgical option. Anatomy should prevail

Acta Neurochir (Wien)

(2010)

W.E. Dandy

The treatment of trigeminal neuralgia by the cerebellar route

Ann Surg

(1932)

Cited by (14)

Intraoperative Mapping of the Sensory Root of the Trigeminal Nerve in Patients with Pontocerebellar Angle Pathology
2023, World Neurosurgery
The aim of the present study was to determine the position of the 3 sensory branches of the trigeminal nerve in the preganglionic tract using intraoperative neurophysiological mapping.
We included consecutive adult patients who underwent neurosurgical treatment of cerebellopontine angle lesions. The trigeminal nerve was antidromically stimulated at 3 sites along its circumference with different stimulus intensities at a distance of ≤1 cm from the brainstem. The sensory nerve action potentials (SNAPs) were recorded from each main trigeminal branch (V1 [ophthalmic branch], V2 [maxillary branch], and V3 [mandibular branch]).
We analyzed 13 patients. The stimulation points at which we obtained the greatest number of congruous and exclusive SNAPs (SNAPs only on the stimulated branch) was the stimulation point for V3 (20.7%). The stimulation intensity at which we obtained the highest number of congruent and exclusive SNAPs with the stimulated branch was 0.5 mA.
Using our recording conditions, trigeminal stimulation is a reliable technique for mapping the V3 and V1 branches using an intensity not exceeding 0.5. However, reliable identification of the fibers of V2 is more difficult. Stimulation of the trigeminal nerve can be a reliable technique to identify the V3 and V1 branches if rhizotomy of these branches is necessary.
Can fifth nerve mapping guide rhizotomy for recurrent trigeminal neuralgia? Case report
2022, Neurochirurgie
Citation Excerpt :
Furthermore, they recognize a topographic somatotopy for the pars major fibers with V1 occupying their posterior and medial portion, whereas V2 and V3 the anterior and lateral ones. In their series, Terrier et al. report intact corneal reflex in all the cases, but a 9% of anesthesia dolorosa of the hemitongue [13]. Unfortunately, their series account for only one patient with previous MVD surgery.
Microvascular decompression (MVD) is usually considered the first-line treatment for trigeminal neuralgia (TN) when medical treatments fail. Recurrence is rare and best treatment option is controversial. MVD was proposed as a feasible and effective technique for recurrent TN by many authors. Nevertheless, in a substantial number of cases, not any impingement or deterioration are found intraoperatively and partial selective rhizotomy is then advised. The rhizotomy site is mostly guided by anatomical landmarks, but variations due to scarring and adhesions are common pitfalls in these second surgeries. Intraoperative monitoring is infrequently used during MVD for trigeminal neuralgia. We describe the use of nerve mapping in a case of recurrence, revealing an unexpected rootlet distribution and thus safely guiding partial rhizotomy.
A 53-year-old woman had suffered from bilateral trigeminal neuralgia for 10 years. Symptoms began on the right side. MVD resolved her symptoms but, after a few months, she developed left TN which persisted after left MVD, radiofrequency and radiosurgery. She was referred to our center for a second MVD on the left side. Intraoperative inspection detected no relevant findings, and nerve mapping followed by partial selective rhizotomy was performed. Complete pain relief was achieved. There were no complications.
Rhizotomy is seldom employed for refractory trigeminal neuralgia. The effects of previous treatments can jeopardize anatomical landmarks. Nerve mapping seems a promising tool to improve results.
Clinical outcomes of partial sensory root rhizotomy on patients with recurrence of multiple sclerosing trigeminal neuralgia after percutaneous balloon compression
2022, Multiple Sclerosis and Related Disorders
Citation Excerpt :
The main cause of classical TN is the compression of abnormal arteries or veins on nerve root entry zone (REZ), and microvascular decompression (MVD) can treat this disease from the etiology with favorable clinical outcomes, fewer complications, and low recurrence rate (Bick and Eskandar, 2017). Secondary TN is mostly caused by tumors of the cerebellopontine angle, aneurysms, multiple sclerosis (MS), etc (Cruccu et al., 2016, Terrier et al., 2018). MS is a chronic inflammatory disease of central nervous system demyelination and axon degeneration with neuropathic pain as its common symptom, called TN-MS. The incidence of TN in MS patients is significantly higher than that in general population.
To investigate the clinical outcomes of partial sensory root rhizotomy (PSR) on patients with recurrence of multiple sclerosing trigeminal neuralgia(TN-MS) after percutaneous balloon compression (PBC).
21 patients with recurrence of TN-MS after PBC were treated with PSR between January 2012 and July 2018. The visual analogue score (VAS) of participants before and after PBC/PSR were observed, and the postoperative recurrence rate of PBC/PSR were recorded, and the postoperative complications were also followed up.
The VAS score reducing to 0-3 points after treatment was defined as effective and ≥4 points as invalid or recurrence. The effective rates of PSR at 1 day, 6 months, 12 months and 18 months after operation were 100%, 100%, 95% and 81%, respectively. The VAS scores of participants after PBC/PSR were significantly lower than those before PBC/PSR (all P<0.05), and the VAS scores at 1 day, 6 months, 12 months and 18 months after PSR were lower than those after PBC (all P<0.05). The postoperative recurrence rates at 6 months, 12 months and 18 months after PSR were significantly lower than those after PBC (all P<0.05). After PSR, all 21 patients had facial sensation loss, and one patient had intracranial infection, and none occurred decrease in masticatory muscle strength, weakened corneal reflex, intracranial hemorrhage, facial paralysis and cerebrospinal fluid leakage.
PSR had a lower pain recurrence rate and a more significant reduction in VAS score compared with PBC, and it could be recommended to treat patients with recurrence of TN-MS after PBC.
Intracranial nociception
2021, Revue Neurologique
Citation Excerpt :
the pars minor, conveying motor fibers coming from the mesencephalic nucleus, is found in the medial part of the trigeminal root. This functional arrangement explains that selective trigeminal rhizotomy lesioning only the lateral pars major may induce facial analgesia without inducing tactile anesthesia [49]. The trigeminal nuclear complex consists of one motor (mesencephalic) nucleus and three sensitive nuclei, all three located in the dorsolateral aspect of the brainstem (Fig. 3): the mesencephalic nucleus, dedicated to the proprioceptive sensitivity; the pontine nucleus, dedicated to the tactile sensitivity; and the spinal nucleus, dedicated to the nociceptive sensitivity.
Understanding intracranial nociceptive innervation is essential to understand the pathophysiology of headaches. Our knowledge about human intracranial nociception comes from sparse observations during neurosurgical procedures performed in awake patients, from human anatomical studies and from experimental studies in animals. In this article we review the anatomical and functional organization underlying nociceptive innervation. Intracranial nociception is mainly mediated by the trigeminal system, except in the posterior cranial fossa that is innervated by the first cervical roots. For decades, the dura mater, its vessels and major cerebral blood vessels were considered as the only intracranial pain-sensitive structures. Recent animal and human studies have suggested that smaller brain arteries and potentially pia mater might also be pain sensitive. Nociceptive neurons innervating intracranial blood vessels project via the ophthalmic division (V1) to the trigeminal ganglion and store several neurotransmitters including glutamate, substance P and calcitonin gene-related peptide (CGRP). The trigeminal ganglion, root and brainstem nuclei have a specific topographic and functional somatotopy. Progressive transition between the trigeminal spinal nucleus and the dorsal horn of the cervical spinal cord, and convergence of nociceptive inputs from the face, intracranial structures and the occipital area on the so-called “trigemino-cervical complex” may explain some headache features, relations between facial and occipital pain, and efficacy of occipital nerve stimulation in headache. The specific anatomic organization of the trigeminal system, from the primary-order neuron in the trigeminal ganglion, to the second-order neuron is the trigeminal nuclei, may explain a part of the various characteristics of headaches.
Treatment Outcomes in Trigeminal Neuralgia–A Systematic Review of Domains, Dimensions and Measures
2020, World Neurosurgery: X
Citation Excerpt :
The IMMPACT Outcome Domains are as follows: 1) Pain; 2) Physical functioning; 3) Emotional functioning; 4) Participant ratings of global improvement/satisfaction; 5) Symptoms and adverse events; and 6) Participant disposition. With the exception of 8 papers, all studies used pain as an outcome domain (Figure 2 and Table 1).13-459 Symptoms and adverse events also were described in a high number of papers (n = 386); however, the impact of treatment on physical and emotional functioning was significantly less evaluated, in 46 and 17 studies, respectively (Tables 2 and 3).460-464
Trigeminal neuralgia (TN) is a painful disorder characterized by sudden electric shock–like pain. It is a rare condition for which multiple treatments are available, including medical and surgical. The best treatment option is yet to be defined, and this is related to the lack of definition in the treatment outcomes and outcome measures. The aim of this systematic review was to summarize all the outcomes and outcomes measures that have been published to date and highlight variability in their use.
We have conducted a literature search using a wide range of databases (1946–2019 for medical and 2008–2019 for surgical treatment), for all intervention studies in TN. Four hundred and sixty-seven studies were selected for data extraction on TN classification, data collection method, intervention, and treatment outcomes mapped to the Initiative on Methods, Measurement, and Pain Assessment in Clinical Trials (IMMPACT guidelines).
Most studies collected data on pain (n = 459) and side effects (n = 386) domains; however, very few collected data on the impact of treatment on physical (n = 46) and emotional functioning (n = 17) and on patient satisfaction (n = 35). There was high variability on outcome measures used for pain relief (n = 10), pain intensity (n = 9), and frequency of pain episodes (n = 3).
A clear definition of what are the important outcomes for patients with TN is essential. The choice of standardized outcome measures allowing for consistent reporting in TN treatment will allow for comparison of studies and facilitate treatment choice for patients and clinicians thus, improving health outcomes and reducing health care cost.
Trigeminal Neuralgias: A Neurosurgical Illustrated Guide
2023, Trigeminal Neuralgias: A Neurosurgical Illustrated Guide

View all citing articles on Scopus

: Conflict of interest statement: The authors declare that the article content was composed in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

View full text

Original ArticleTherapeutic Failure in Trigeminal Neuralgia: from a Clarification of Trigeminal Nerve Somatotopy to a Targeted Partial Sensory Rhizotomy

Highlights

Background

Objective

Methods

Results

Conclusions

Introduction

Section snippets

Data Collection

Surgical Procedure

Results

Discussion

Conclusions

Acknowledgments

Pain

Neuroscience

J Chem Neuroanat

Patient reports of satisfaction after microvascular decompression and partial sensory rhizotomy for trigeminal neuralgia

Neurosurgery

Trigeminal neuralgia: New classification and diagnostic grading for practice and research

Neurology

The long-term outcome of microvascular decompression for trigeminal neuralgia

N Engl J Med

Neurovascular compression in cranial nerve and systemic disease

Ann Surg

Systematic review of ablative neurosurgical techniques for the treatment of trigeminal neuralgia

Neurosurgery

Stereotactic radiosurgery for primary trigeminal neuralgia: state of the evidence and recommendations for future reports

J Neurol Neurosurg Psychiatry

A review of percutaneous treatments for trigeminal neuralgia

Neurosurgery

Microvascular decompression for trigeminal neuralgia: comments on a series of 250 cases, including 10 patients with multiple sclerosis

J Neurol Neurosurg Psychiatry

An operation for the cure of tic douloureux. Partial section of the sensory root at the pons

Arch Surg

Advances in neuropathic pain: diagnosis, mechanisms, and treatment recommendations

Arch Neurol

Trigeminal neuralgia: a plea for microvascular decompression as the first surgical option. Anatomy should prevail

Acta Neurochir (Wien)

The treatment of trigeminal neuralgia by the cerebellar route

Ann Surg

Original Article
Therapeutic Failure in Trigeminal Neuralgia: from a Clarification of Trigeminal Nerve Somatotopy to a Targeted Partial Sensory Rhizotomy