Trigeminal neuralgia and neuropathy in large sporadic vestibular schwannomas

The efficacy of surgery over stereotactic radiosurgery in the management of tumor-related trigeminal neuralgia

Tumor-related trigeminal neuralgia (TN) is a deeply debilitating condition that severely impacts patient quality of life. Two principal treatment methods in use are open surgical resection of the causative tumor or the use of stereotactic radiosurgery (SRS). In this letter, we aim to evaluate the use of both treatment methods and highlight that in patients with commensurate anatomy, open surgical resection continues to provide greater rates of symptomatic relief, lower rates of recurrence, and complication compared to stereotactic radiosurgery.

Surgical and radiosurgical outcomes for Koos grade 3 vestibular schwannomas

This study aimed to reveal the preferred initial treatment for Koos grade 3 vestibular schwannomas (VS). We performed a two-institutional retrospective study on 21 patients with Koos grade 3 VS undergoing resection at Yokohama Medical Center and 37 patients undergoing radiosurgery at Yokohama Rosai Hospital from 2010 to 2021. Tumor control, complications, and functional preservation were compared. The median pre-treatment volume and follow-up duration were 2845 mm3 and 57.0 months, respectively, in the resection group and 2127 mm3 and 81.7 months, respectively, in the radiosurgery group. In the resection group, 16 (76.2%) underwent gross total resection, and three patients (14.3%) experienced regrowth; however, no one required additional treatment. In the radiosurgery group, the tumor control rate was 86.5%, and three cases (8.1%) required surgical resection because of symptomatic brainstem compression. Kaplan-Meier analyses revealed that tumors with delayed continuous enlargement and large thin-walled cysts were significantly associated with poor prognostic factors (p = 0.0027, p < 0.001). The pre-radiosurgery growth rate was also associated with the volume increase (p = 0.013). Two cases (9.5%) required additional operation due to complications such as post-operative hematoma and cerebrospinal fluid leaks in the resection group, whereas temporary cranial neuropathies were observed in the radiosurgery group. Two patients (9.5%) had poor facial nerve function (House-Brackmann grading grade 3) in the resection group, while no one developed facial paresis in the radiosurgery group. Trigeminal neuropathy improved only in the resection group.Radiosurgery can be considered for the treatment of Koos grade 3 VS for functional preservation. However, resection may also be considered for patients with severe trigeminal neuropathy or a high risk of volume increments, such as large thin-walled cysts and rapid pre-treatment growth.

Delayed Facial Nerve Dysfunction Following CyberKnife® Radiosurgery for Vestibular Schwannoma

OBJECTIVE

The incidence and risk factors for facial nerve dysfunction (FND) following CyberKnife® therapy for vestibular schwannoma (VS) remain poorly understood. This study investigates whether differential radiation doses to vulnerable segments of the facial nerve may be associated with FND outcomes.

METHODS

Patients were identified who underwent CyberKnife® radiosurgery for VS at a single institution. Basic demographics, tumor characteristics, and facial nerve function were collected. Total radiation doses to tumor, internal auditory canal (IAC), and labyrinthine segment of facial nerve (LSFN) were evaluated.

RESULTS

Six out of 64 patients experienced FND following CyberKnife® treatment for VS (9.38%, 6/64). Patients with FND were compared to those without FND (control). Of the 64 patients, complete radiation records were obtained for 30 patients (6 FND vs. 24 control). There were no significant differences in demographic or tumor characteristics between control and FND cohorts. More severe FND (HB ≥ 4) had significantly larger tumors (3.74 vs. 1.27 cm3, p = 0.037) with directionally decreased time to FND (3.50 vs. 33.5 months, p = 0.106) than patients with HB < 4, respectively. There were directionally, nonsignificant differences between maximum radiation doses to the LSFN (2492.4 vs. 2557.0 cGy, p = 0.121) and IAC (2877.3 vs. 2895.5 cGy, p = 0.824) between the control and FND cohorts, respectively.

CONCLUSIONS

FND may represent an underrecognized sequelae of CyberKnife® radiosurgery for VS that can occur many months following treatment. Further studies are needed to elucidate the effect of differential radiation exposure to the facial nerve with FND following treatment.

LEVEL OF EVIDENCE

III (Retrospective Cohort Study) Laryngoscope, 2024.

Open surgery vs. stereotactic radiosurgery for tumour-related trigeminal neuralgia: A systematic review

BACKGROUND

Secondary trigeminal neuralgia is a facial pain in trigeminal nerve dermatome caused by an underlying disease, such as cerebellopontine angle tumours. Treatment options to relieve the pains were surgical tumour resection and stereotactic radiosurgery of the tumour or trigeminal nerve. This study aims to review the efficacy of open surgery and stereotactic radiosurgery and recommend the treatment of choice for secondary trigeminal neuralgia due to cerebellopontine angle tumours.

METHOD

The inclusion criteria were studies covering patients with trigeminal neuralgia associated with cerebellopontine angle tumours that were treated with either open surgery or stereotactic radiosurgery and reported pain outcomes after treatment. Non-English articles or studies with a population of less than five were excluded. We systematically searched studies from PubMed, Ebscohost, and Cochrane Library from inception until December 20, 2021. Several works of literature from manual search were also added. Selected articles were appraised using a critical appraisal tool for prognostic studies.

RESULT

Included articles were 26 retrospective studies and one prospective study comprising 517 patients. Of 127 schwannomas, 226 epidermoids, 154 meningiomas, and ten other tumours, 320 cases received surgical tumour excision with or without MVD, 196 had tumour-targeted radiosurgery, and 22 underwent nerve-targeted radiosurgery. In surgical series, 92.2 % gained pain improvement, 2.8 % were unchanged, and 4.5 % had recurrence; none of the patients had worsened outcomes. In cases treated with tumour-targeted radiosurgery, the improvement rate was 79.1 %, unchanged at 14.3 %, recurrence at 26.5 %, and worse symptoms rate after the intervention was 6.6 %. Six patients with recurrent pain after tumour-targeted radiosurgery received secondary nerve-targeted radiosurgery with improved outcomes. Only one patient in our review underwent primary nerve-targeted radiosurgery, and the result was satisfactory. One study treated 15 patients with a single session of tumour-targeted and nerve-targeted radiosurgery, with an improvement rate of 93.3 % and a recurrence rate of 21.4 %.

CONCLUSION

Open surgery releasing the nerve root from compressive lesions is advocated to be the first-line treatment to gain satisfactory outcomes. Total removal surgery is recommended if possible. Nerve-targeted radiosurgery should be reserved as a secondary treatment for recurrent cases.

Trigeminal Sensory Neuropathy Predicts Chemosensory Dysfunction After Skull Base Surgery

BACKGROUND

Trigeminal sensory neuropathy, characterized by diminished or exaggerated/painful sensation along the distribution of trigeminal branches, is one of the complications after skull base surgery. These procedures can also affect chemosensory functions and compromise the patients' quality of life.

OBJECTIVE

To examine those postoperative complications in chemosensory and facial cutaneous sensory functions as well as their interaction.

METHODS

A total of 61 patients being operated for various pathologies in the vicinity of trigeminal pathway (17 with trigeminal neuralgia, 20 with meningiomas, and 24 with vestibular schwannomas) and 50 healthy controls were enrolled in this case-control study. Postoperative trigeminal neuropathic symptoms were evaluated. The olfactory, gustatory, and intranasal trigeminal functions were assessed using the Sniffin' Stick olfactory test, lateralized taste strip test, and the lateralized intranasal trigeminal CO 2 detection thresholds, respectively.

RESULTS

Patients with trigeminal neuralgia and meningioma had relatively decreased olfactory function, whereas those with vestibular schwannoma had a relative decrease in taste function. As for the relationship between the distribution of trigeminal neuropathy and chemosensory dysfunction, we found that V3 involvement predicted lower side-specific taste function. In addition, V2/V3 involvement predicted relatively lower side-specific intranasal trigeminal function.

CONCLUSION

The present results suggest a differential involvement of the chemical senses in relation to the site and pathology of the lesions after surgery. The presence of trigeminal neuropathy is associated with taste and intranasal trigeminal dysfunction. The results serve as a basis for consultation regarding outcome prediction and patient education.

Emerging roles of lncRNAs in the pathogenesis, diagnosis, and treatment of trigeminal neuralgia

Trigeminal neuralgia (TN) is one of the most common neuropathic pain disorders and is often combined with other comorbidities if managed inadequately. However, the present understanding of its pathogenesis at the molecular level remains lacking. Long noncoding RNAs (lncRNAs) play crucial roles in neuropathic pain, and many studies have reported that specific lncRNAs are related to TN. This review summarizes the current understanding of lncRNAs in the pathogenesis, diagnosis, and treatment of TN. Recent studies have shown that the lncRNAs uc.48+, Gm14461, MRAK009713 and NONRATT021972 are potential candidate loci for the diagnosis and treatment of TN. The current diagnostic system could be enhanced and improved by a workflow for selecting transcriptomic biomarkers and the development of lncRNA-based molecular diagnostic systems for TN. The discovery of lncRNAs potentially impacts drug selection for TN; however, the current supporting evidence is limited to preclinical studies. Additional studies are needed to further test the diagnostic and therapeutic value of lncRNAs in TN.

A Historical Note on the Treatment of Trigeminal Neuralgia

Trigeminal neuralgia, otherwise known under the French denomination of tic douloureux, is a chronic painful condition of a particular severity. Its descriptions are numerous and date back to centuries before. Although the anatomy of the trigeminal nerve has been well known, the pathophysiology and hence the treatment of this disease has been largely fortuitous. Disparate pharmacological and surgical approaches have been tried, some of them heralding a much-required therapeutic success. The authors make a brief description of the first sources that have systematized the disease, along with all therapies documented in a written form, especially from indexed journals of the two last centuries. Very few remnants of the previous therapies, actually considered obsolete, have survived to the proof of time; one of them relies on the possible role of the autonomic nervous system and anticholinergic therapies, later replaced from modern conservative and interventional approaches. Anticonvulsants have been, since 1940, the mainstay of the therapy, however, progressions in neurosurgery and mini-invasive procedures have substantially improved the quality of life and the prognosis of an otherwise very painful and chronic condition.

Right medium-sized vestibular schwannoma with trigeminal neuralgia post-fractionated radiotherapy

A patient with trigeminal neuralgia secondary to a vestibular schwannoma underwent fractionated radiotherapy without relief of her pain. She was then effectively treated with microsurgical resection of her tumor. Early identification of the lower cranial nerves and the origin of the facial and vestibulocochlear nerves is key to determining the operative corridors for vestibular schwannoma resection. To effectively treat trigeminal neuralgia, the trigeminal nerve root entry zone and motor branch are clearly identified and decompressed. Fractioned radiotherapy does not effectively treat trigeminal neuralgia secondary to vestibular schwannoma compression.

The video can be found here: https://stream.cadmore.media/r10.3171/2021.7.FOCVID21112

A case of vestibular schwannoma with oral burning sensation: surgical complication or burning mouth syndrome?

BACKGROUND

Despite improvements in surgical techniques, the removal of vestibular schwannoma is related to some complications. Recovery from surgical complications of vestibular schwannoma is often difficult and complications sometimes lead to permanent deficits. However, treatable trigeminal symptoms may be missed in atypical cases.

CASE PRESENTATION

A 46-year-old woman complained about burning sensation on her tongue and maxilla for four years before her first visit to our clinic. She visited the neurosurgery department in a university hospital because her facial pain and burning sensation of her tongue were suddenly aggravated. She was diagnosed with vestibular schwannoma and tumour resection was performed. However, her oral pain persisted after surgery. Two months before the initial visit to our clinic, the oral pain became more severe than ever before. When the patient visited a psychiatrist due to a panic attack, the psychiatrist diagnosed her as having somatic symptom disorder and depression and referred her to our clinic. Based on the characteristics of the pain, she was diagnosed as burning mouth syndrome and treated for the same. Within 1.5 months, the pain and burning sensation of the tongue and maxilla almost completely remitted with low dose amitriptyline.

CONCLUSIONS

Our case suggests that there are exceptional cases in which burning mouth syndrome and vestibular schwannoma occur simultaneously. Burning pain after vestibular schwannoma surgery cannot always be considered a complication of surgery.

[Trigeminal radiculopathy in vestibular schwannomas]

OBJECTIVE

To evaluate the correlation of trigeminal radiculopathy with anatomical relationships of trigeminal nerve root, brainstem, tumors and vessels in patients with vestibular schwannomas.

MATERIAL AND METHODS

A retrospective analysis included 153 patients (106 females and 47 males aged 22-82 years) with vestibular schwannomas who underwent surgery via retromastoid approach. Preoperative trigeminal radiculopathy (facial pain and sensory disturbances) was examined after microsurgical resection. Brainstem compression was analyzed by comparison of transverse size of contralateral to vestibular schwannoma half of brainstem and ipsilateral side.

RESULTS

Tumor-induced brainstem and trigeminal nerve compression was found in 115 cases. Sixty-four of these patients had trigeminal radiculopathy symptoms. Degree of brainstem compression was significantly higher in trigeminal radiculopathy group. Facial hypoesthesia was found in 61patients, trigeminal neuralgia - in 5 cases, neuropathic pain - in 3 patients. Thirty-seven patients without brainstem compression had no trigeminal nerve involvement. One patient had trigeminal neuralgia following compression by superior cerebellar artery. Total resection with brainstem and trigeminal nerve decompression were performed in all cases. Isolated or combined compression of trigeminal nerve root was noted in 9 patients with trigeminal neuralgia and neuropathic pain, in 2 with facial numbness and in 2 patients without trigeminal symptoms. In case of trigeminal neuralgia following compression by superior cerebellar artery, vascular decompression was performed only in patients with facial pain and numbness. Facial pain completely resolved in all patients. Complete or partial sensory restoration was noted in 25 cases. No facial sensory disorders were noted in 26 cases, transient sensory deterioration - in 10 patients.

CONCLUSION

Trigeminal radiculopathy is caused by severe brainstem compression following vestibular schwannomas and usually results sensory disturbances and rarely facial pain. The impact of tumor on trigeminal nerve root and brainstem trigeminal pathways can be accompanied by vascular compression by superior cerebellar artery. Regression of trigeminal radiculopathy symptoms after resection of vestibular schwannoma is caused by decompression of trigeminal nerve root and brainstem. In case of concomitant neurovascular syndrome, vascular decompression is indicated.

Radiosurgery for Epidermoid Tumors: Dramatic Pain Relief from Trigeminal Neuralgia

Purpose 

The purpose of this study is to discuss the long-term effects of radiosurgery for epidermoid tumors, including the symptoms of trigeminal neuralgia and/or facial spasm, which we have originally reported before.

Background

Intracranial epidermoids are slow-growing tumors that can become symptomatic once they develop into large tumors. The mainstay of the treatment is surgery. However, eradicating the whole tumor is often difficult and some tumors may recur. In addition to their mass effects on the brain, these tumors are often associated with hyperactive nerve dysfunction syndromes such as trigeminal neuralgia, glossopharyngeal neuralgia, and/or facial spasm.

Cases and methods 

We report 13 cases of epidermoid tumors, 12 of which were located in the cerebellopontine angle (CPA), which were treated using 14 radiosurgery procedures. The inclusion criteria for radiosurgery were the presence of well-localized small tumors and/or severe associated neuralgia or facial spasms. The mean target volume ranged from 0.17 to 9.5 cm³ with a mean of 2.85 cm³. The lesions were treated with a mean maximum and a marginal dose of 28.2 Gy and 14.2 Gy, respectively.

Results

Among the 14 gamma knife procedures that were performed in 13 patients, dose planning to ensure total and partial coverage for relief from hyperactive cranial nerve dysfunction (HCND) was performed. Six cases were totally and another eight were partially covered at the dose planning. The irradiated tumors showed a minor decrease or no remarkable changes during a mean follow-up period of 86.1 months. Tumor progression requiring a second surgery was seen in two cases. The trigeminal neuralgias either improved or disappeared soon after the procedure, enabling the discontinuation of the medication.

Conclusion 

Radiosurgery led to a dramatic improvement in HCND. In fact, the immediate cure of neuralgia after the radiosurgery was observed in several cases, even after partial coverage with radiosurgery. The interface between the tumor and the nerve was the main target. The definite mechanisms for this favorable outcome have not been verified yet, but the functional modulation by the radiosurgery could be one. Electrophysiological alteration at the interface between the tumor and nerve has been considered. When the tumors were totally covered with radiosurgery, persistent tumor control was expected. Sufficient tumor control is possible if the tumor can be covered entirely with radiosurgery. Functional modulation of trigeminal neuralgia and facial spasms can also be attained even by partial dose planning for the nerve-tumor interface.

[Anatomical rationale for surgical treatment of trigeminal neuralgia combined with cerebellopontine angle tumors]

Trigeminal neuralgia (TN) can be combined with tumors of the cerebellopontine angle (CPA). The optimal surgical management in these cases depends on the anatomical relationship of the trigeminal nerve root (TNR) with tumors and vessels. The purpose of this study is to evaluate variants of the anatomical relationship between the TNR and the surrounding structures as well as to analyze the results of using various surgical techniques for treatment of TN in CPA tumors.

MATERIAL AND METHODS

We performed a retrospective analysis of 51 patients (38 females and 13 males aged 22 to 77 years) with TN and ipsilateral CPA tumors. Space-occupying lesions were represented by 29 meningiomas of the petrous apex, 11 epidermoids, 9 vestibular schwannomas, 1 hemangioma, and 1 cavernoma.

RESULTS

Intraoperatively, we identified 6 types of the anatomical relationships among the TNR, tumors, and CPA vessels: type I - the TNR is completely surrounded by the tumor (4 epidermoids); type II - the tumor compresses and displaces the TNR (21 meningiomas, 4 schwannomas, and 6 epidermoids); type III - the tumor occurs inside the TNR (1 cavernoma); type IV - the tumor together with the vessel compresses the TNR (3 meningiomas and 1 epidermoid); type V - the tumor displaces the TNR towards the vessel (5 meningiomas and 5 schwannomas); type VI - the tumor does not contact the TNR that is compressed by the vessel (1 hemangioma). Preoperative MRI and intraoperative findings revealed compression and deformity of the brain stem at the TNR entry level in all but two patients. Vascular compression of the TNR (usually by the superior cerebellar artery) was found in 15 of 51 patients. Microvascular decompression (MVD) was performed using various techniques: interposition of implants between vessels and the TNR, transposition of the compressing vessels from the TNR, or transposition of the nerve root. In all patients, except 1, pain syndrome regressed immediately after tumor removal and MVD. In 1 case, the pain syndrome did not regress after total removal of epidermoid and MVD, and TN was resolved by percutaneous radiofrequency rhizotomy. Long-term postoperative follow-up results showed complete elimination of TN in all cases; there were no persistent neurological complications and postoperative mortality.

CONCLUSION

TN may result from direct compression and deformation of the TNR and brain stem by CPA tumors. In some cases, the cause of TN is combined compression of the TNR by the tumor and vessels. Assessment of the neurovascular relationships requires detailed examination of the entire TNR after tumor removal. In the case of vascular compression of the TNR, various MVD techniques can be used for treatment of TN.

Trigeminal neuropathy in vestibular schwannoma: a treatment algorithm to avoid long-term morbidity

BACKGROUND

Trigeminal neuropathy (TGN) can occur as a presenting feature of vestibular schwannoma (VS) or as an adverse effect of radiosurgery. This study was designed to evaluate a treatment algorithm for presenting symptoms of TGN in patients with VS, and a new radiosurgery dosimetric tolerance to avoid TGN after treatment. Outcome was measured after microsurgery (MS), stereotactic radiosurgery (SRS), hypofractionated stereotactic radiotherapy (HSRT), and fractionated radiotherapy (FRT).

METHODS

A prospectively held VS database was retrospectively analysed from 2011 to 2016 at a tertiary university hospital. All patients who underwent MS from 2011 and all patients who underwent radiotherapy (SRS, HSRT, FRT) from 2015 were studied. Patients on surveillance and neurofibromatosis type 2 patients were not included. Patient demographic data, tumour characteristics, presenting symptoms, and post-treatment outcomes were analysed.

RESULTS

Eighty-eight patients were included in the study (43 microsurgery, 45 radiotherapy). Twenty-seven (31%) patients presented with TGN symptoms. The median age of patients included was 56.5 (range 6-72 years), with a median follow-up for MS and SRS of 38 and 20 months, respectively (range 10-80 months). All 27 patients with TGN were offered MS as per protocol. Three patients declined, or were not fit for surgery, and received FRT. Complete resolution of TGN symptoms was achieved in all 24 patients who underwent MS and 33% (1/3) of patients with FRT. Eleven patients experienced transient post-operative complications (pseudomeningocele (6), meningitis (3), venous sinus thrombosis, cerebellar haemorrhagic contusion, and posterior fossa haematoma). Of the 45 patients in the radiotherapy cohort, 36 were suitable for SRS, of which 30 patients who met the dose-volume constraints for trigeminal nerve underwent single-fraction SRS and 6 patients who did not meet the constraints received HSRT. Nine patients (20%) received FRT including three patients with pre-treatment TGN. None of the patients developed new TGN symptoms following SRS or HSRT.

CONCLUSIONS

Our algorithm to select the optimal treatment modality appears to achieve comparable or better long-term outcome. Microsurgical resection in our cohort resulted in complete resolution of symptoms in all patients. None of our SRS- or HSRT-treated patients developed TGN during the follow-up period. The adherence to strict trigeminal nerve dose-volume constraints for SRS remains critical to minimise TGN post treatment. Fractionated radiotherapy is an alternative for patients who refuse surgery or those who are unfit for surgery.