trigeminal neuralgia and neuropathy in large sporadic ... · clinical article j neurosurg...

CLINICAL ARTICLEJ Neurosurg 127:992–999, 2017

ABBREVIATIONS BNI = Barrow Neurological Institute; CPA = cerebellopontine angle; GKS = Gamma Knife surgery; SRS = stereotactic radiosurgery; TN = trigeminal neuralgia; VS = vestibular schwannoma.SUBMITTED February 29, 2016. ACCEPTED September 15, 2016.INCLUDE WHEN CITING Published online January 13, 2017; DOI: 10.3171/2016.9.JNS16515.

Trigeminal neuralgia and neuropathy in large sporadic vestibular schwannomasBrian A. Neff, MD,1 Matthew L. Carlson, MD,1 Megan M. O’Byrne, MA,3 Jamie J. Van Gompel,2 MD, Colin L. W. Driscoll, MD,1 and Michael J. Link, MD2

Departments of 1Otorhinolaryngology and 2Neurologic Surgery, School of Medicine, and 3Department of Biomedical Statistics and Informatics, Mayo Clinic, Rochester, Minnesota

OBJECTIVE The aim of this study was to evaluate the incidence, presentation, and treatment outcomes of trigeminal nerve–mediated symptoms secondary to large vestibular schwannomas (VSs) with trigeminal nerve contact. Specifically, the symptomatic results of pain, paresthesias, and numbness after microsurgical resection or stereotactic radiosurgery (SRS) were examined.METHODS The authors conducted a retrospective review of a database for concomitant diagnosis of trigeminal neural-gia (TN) or trigeminal neuropathy and VS between 1994 and 2014 at a tertiary academic center. All patients with VS with TN or neuropathy were included, with the exception of those patients with neurofibromatosis Type 2 and patients who elected observation. Patient demographic data, symptom evolution, and treatment outcomes were collected. Population data were summarized, and outcome comparisons between microsurgery and SRS were analyzed at last follow-up.RESULTS Sixty (2.2%) of 2771 total patients who had large VSs and either TN or neuropathy symptoms met inclusion criteria. The average age of trigeminal symptom onset was 53.6 years (range 24–79 years), the average age at VS diag-nosis was 54.4 years (range 25–79 years), and the average follow-up for the microsurgery and SRS groups was 30 and 59 months, respectively (range 3–132 months). Of these patients, 50 (83%) had facial numbness, 16 (27%) had TN pain, and 13 (22%) had paresthesias (i.e., burning or tingling). Subsequently, 50 (83%) patients underwent resection and 10 (17%) patients received SRS.Treatment of VS with SRS did not improve trigeminal symptoms in any patient. This included 2 subjects with unimproved facial numbness and 4 patients with worsened numbness. Similarly, SRS worsened TN pain and paresthesias in 5 pa-tients and failed to improve pain in 2 additional patients. The Barrow Neurological Institute neuralgia and hypesthesia scale scores were significantly worse for patients undergoing SRS compared with microsurgery.Resection alleviated facial numbness in 22 (50%) patients, paresthesias in 5 (42%) patients, and TN in 7 (70%) patients. In several patients, surgery was not successful in relieving facial numbness, which failed to improve in 17 (39%) cases and became worse in 5 (11%) cases. Also, surgery did not change the intensity of facial paresthesias or neuralgia in 6 (50%) and 3 (25%) patients, respectively. Microsurgery exacerbated facial paresthesias in 1 (8%) patient but, notably, did not aggravate TN in any patient.CONCLUSIONS Overall, resection of large VSs provided improved outcomes for patients with concomitant TN, facial paresthesia, and numbness compared with SRS. However, caution should be used when counseling surgical candidates because a number of patients did not experience improvement. This was especially true in patients with preoperative facial numbness and paresthesias, who frequently reported that these symptoms were unchanged following surgery.https://thejns.org/doi/abs/10.3171/2016.9.JNS16515KEY WORDS vestibular schwannoma; acoustic neuroma; trigeminal neuralgia; trigeminal neuropathy; surgery; radiosurgery; oncology; pain

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Trigeminal neuralgia in vestibular schwannoma

J Neurosurg Volume 127 • November 2017 993

Tumor-relaTed facial pain accounts for approxi-mately 1%–13% of patients with clinical trigeminal neuralgia (TN) symptoms.4,23 Many of these cases

are caused by trigeminal schwannomas or petroclival me-ningiomas, but trigeminal nerve symptoms are also seen with posterior fossa cerebellopontine angle (CPA) tumors such as vestibular schwannomas (VSs). VS-related TN and trigeminal neuropathy are thought to occur from direct tu-mor pressure on the trigeminal nerve, which causes de-myelination of the somatosensory and pain fibers or, less likely, from a tumor pushing the trigeminal nerve and an artery into contact.6,14,21 The incidence of TN and trigemi-nal neuropathy varies among publications, with higher rates observed in series containing larger VSs. A few VS studies report pretreatment TN and trigeminal neuropathy in 9.8%–15% of presenting patients.2,20

Currently, there is a paucity of reports on the best VS treatment approach for those patients who present with trigeminal symptoms. Small case series and expert opin-ion promote microsurgical tumor removal for treatment of the tumor while simultaneously providing decompres-sion of the fifth cranial nerve.34 A surgical bias is also probably present due to the fact that many patients with trigeminal symptoms tend to have larger tumors that are also causing brainstem compression and hydrocephalus, which require surgical treatment. It is for this reason that most radiosurgery centers will not perform stereotactic radiosurgery (SRS) for treatment of tumors > 3 cm.33,34 However, there are very few studies to guide treatment decisions in those tumors that are amenable to either SRS or surgery.

MethodsFollowing institutional review board approval, a pro-

spectively maintained VS clinical database was retro-spectively queried for concomitant diagnosis of TN or trigeminal neuropathy and VS between 1994 and 2014. The study population included patients with only sporadic VS because patients with neurofibromatosis Type 2–as-sociated VS can often develop trigeminal schwannomas or petroclival meningiomas during their clinical course, making VS causality of trigeminal symptomatology dif-ficult to determine. A total of 2771 patients with VSs were seen during that time, of whom 100 patients also had a concomitant diagnosis of TN.

Patients had typical (Type 1) TN or atypical (Type 2) TN. Typical TN was defined as a paroxysmal pain that was either lancinating, boring, stabbing, or an intense elec-trical zap in the trigeminal nerve distribution. Atypical TN was defined as typical TN symptoms with concomi-tant persistent facial pain between paroxysms.36 To have the pain symptoms attributed to the VS, only tumors with physical contact with the trigeminal nerve were included. For example, internal auditory canal tumors on the same side as the TN were excluded from analysis.

For the purpose of this study, paresthesia (dysesthesia) was defined as a sensation of pricking, tingling, itchy-pricking, or creeping on the skin, usually associated with irritation of a sensory nerve or nerve root. Numbness was defined as a reduced sensitivity to touch.36 The minimum

required length of follow-up to be included was 3 months. Of the 100 patients, only 60 met all study inclusion cri-teria, with the other 40 patients excluded due to the fol-lowing reasons: the neuralgia or numbness only occurred after treatment; no follow-up; tumor diagnosis and TN were unrelated (either tumor was too small to contact the trigeminal nerve or the conditions were present on oppo-site sides); incomplete charting on a few earlier entries; 3 cases were neurofibromatosis Type 2–associated VSs; and 5 patients elected tumor observation.

Retrospective data analysis included age at time of VS and TN diagnosis; sex; side; presence of pretreatment neuralgia, numbness, or paresthesias; Barrow Neurologi-cal Institute (BNI) neuralgia and numbness scale scores; coexisting headache or pain disorder; previous medical or TN treatments; surgical approach; tumor resection com-pleteness; inadvertent intraoperative fifth nerve injury (partial or complete transection); presence of a compres-sive vessel on the trigeminal nerve; concurrent microvas-cular decompression with tumor removal; postoperative neuralgia, numbness, or paresthesia outcome; time until symptom improvement; tumor size; cystic nature of tumor; pain medication reduction; SRS treatment details includ-ing treatment volume, central and marginal dose, number of isocenters, surgical and radiation complications (e.g., facial paralysis); and duration of follow-up (defined as the time from the date of treatment to the last follow-up visit that mentioned trigeminal symptom or sign outcomes).

The BNI neuralgia scale was used to classify TN out-come: Class I, no trigeminal pain, no medication; Class II, occasional pain, not requiring medication; Class IIIa, no pain with continued medication; Class IIIb, pain controlled with medication; Class IV, some pain, not adequately con-trolled with medication; and Class V, severe pain, no pain relief.28,31 For purposes of statistical comparison, Groups IIIa and IIIb were combined into a single Group III. The degree of hypesthesia was reported using the BNI facial hypesthesia scale: Class I, no facial numbness; Class II, mild facial numbness, not bothersome; Class III, facial numbness, somewhat bothersome; and Class IV, facial numbness, very bothersome.28

Descriptive statistics were used to summarize demo-graphic and clinical data. Patients who received SRS were compared with those who received surgery across several parameters, and only univariate results were reported. Or-dinal parameters, such as BNI pain (I–V, with V being worst) and postoperative change in pain (better, same, or worse), were analyzed with Mantel-Haenszel chi-square tests using ridit scores to account for the ordering of the levels.3 A significant p value from the ridit analysis can be interpreted as meaning that 1 treatment showed sig-nificantly better outcomes than the other, and this was un-likely to be due to chance alone. For unordered variables, Fisher’s exact tests were used. A p value < 0.05 was con-sidered significant for all tests. All analyses were run with SAS version 9.4 (SAS Institute).

ResultsA total of 2771 patients with the diagnosis of VS were

evaluated between 1994 and 2014. One hundred of these


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patients had a concomitant diagnosis of TN or trigeminal neuropathy. Of these 2771 patients, 60 (2.2%) had trigemi-nal nerve–related symptoms that could be directly attrib-uted to the tumor, whether they were neuralgia, paresthe-sia, hypesthesia, or a combination, prior to treatment with microsurgery or radiosurgery. In the microsurgery cohort, 37 patients perceived only 1 symptom, and 13 patients re-ported multiple symptoms, which are outlined in Table 1. Of the microsurgery patients, 44 of 50 (88%) perceived numbness, 12 of 50 (24%) suffered paresthesia, and 10 of 50 (20%) reported neuralgia. In the radiosurgery group, 7 patients experienced only 1 symptom prior to treatment, whereas 3 patients experienced multiple symptoms, which are summarized in Table 1. In the Gamma Knife Surgery (GKS)–treated cohort, 6 of 10 (60%) patients had numb-ness, 6 of 10 (60%) had neuralgia, and 1 of 10 (10%) had facial paresthesia.

Of these 60 patients, 50 were treated with microsur-gery (39 retrosigmoid, 11 translabyrinthine) and 10 pa-tients were treated with SRS. At our center, patients with a tumor > 2.5 cm were primarily counseled to undergo surgery; however, there were a few patients in this group who refused surgery and were treated with GKS. For cas-es in which tumors were ≤ 2.5 cm, the patient was given the choice between microsurgery or radiosurgery, unless medical comorbidities precluded microsurgery. The aver-age age at TN or neuropathy diagnosis was younger than the average age at VS diagnosis (53.6 years vs 54.4 years, respectively). There were 31 women and 29 men, with an average follow-up of 30 months for the microsurgery group and 59 months for the SRS group.

The average tumor size for all patients was 3.0 cm, us-ing the greatest CPA measurement from the axial or coro-nal MR images, and the average tumor size was signifi-cantly larger in the microsurgery group compared with the radiosurgery patients (3.2 cm vs 2.1 cm, respectively, p < 0.0001, range 2.0–4.5 cm vs 1.4–2.8 cm, respectively). Of the 60 patients with VS, 13 (22%) had macrocystic tumors on MRI, which were confirmed with surgical findings (Fig. 1). Eight of the patients who underwent GKS were treated to a marginal dose of 12–13 Gy, and 2 patients received higher marginal doses of 14 Gy and 18 Gy. No radiosurgery cases received a boost dose to the trigeminal nerve.

In the microsurgery group, 20 patients had complete tu-mor resection, 11 patients had near-total resection (defined as a tumor remnant < 5 × 5 × 2 mm), and 19 patients had a subtotal resection of their VS. All of the subtotal resec-tions were relatively aggressive, with > 90% of the tumor removed, and the brainstem was always decompressed. The main reason for leaving tumor in the subtotal and near-total groups was due to severe splaying of the facial nerve with unfavorable surgical planes. Other reasons, in descending order of frequency, included the following: un-favorable surgical plane with the brainstem; preservation of the fifth cranial nerve or lower cranial nerves; excessive tumor bleeding; and preservation of critical vasculature that could not be separated from the tumor.

There were 4 cases where tumor was left on the trigem-inal nerve to preserve neural function. In all of these cas-es, it was believed that removing the majority of the tumor

relieved the mass effect on the nerve, and 3 of 5 preexist-ing trigeminal-related symptoms in these 4 patients were improved postoperatively. This constituted too few cases to analyze whether this detrimentally affected symptom outcomes compared with removing the entire tumor from around the trigeminal nerve. There was only 1 case where the trigeminal nerve was thought to be partially transected (< 50% of the nerve). This was in a patient with preop-erative numbness, which did not improve or worsen after surgery. There was only 1 case where a vessel (superior cerebellar artery) was causing significant compression of the trigeminal nerve. In this instance, a microvascular de-compression with Teflon felt was performed after tumor removal.

Patient-reported outcomes for post-treatment symp-toms are reported in Figs. 2 and 3. Surgery was more likely to relieve numbness (22 of 44 [50%]) than GKS, in which group there was no patient improvement. Surgery was also more likely to relieve paresthesias (5 of 12 [42%]) and neuralgia (7 of 10 [70%]) than GKS, which did not result in any improvements in either symptom in any pa-tient. All of these results were statistically significant. The BNI provides a validated outcome scale for these subjec-tive symptoms, and the results are summarized in Figs. 4 and 5. Again, microsurgery provided statistically signifi-cant, greater symptom relief than GKS when evaluating the BNI scales. There were no cases, in either group, with recurrent trigeminal nerve symptoms (defined as a period of complete symptom relief followed by recurrence of tri-geminal symptoms).

Several demographic variables and patient factors were analyzed to assess whether anything was predictive of a poor symptom outcome after treatment, and the results

TABLE 1. Pretreatment symptoms in 60 patients with VS

Variable*Value (%)

Microsurgery Radiosurgery

Total no. of pts 50 10Numbness 31 3Paresthesia 0 1Neuralgia 6 3Numbness + neuralgia 1 3Numbness + paresthesia 8 0Numbness + paresthesia + neuralgia 4 0Total pts w/ numbness 44 (88) 6 (60)Total pts w/ paresthesia 12 (24) 1 (10)Total pts w/ neuralgia 10 (20) 6 (60)Mean age at trigeminal symptom onset, yrs

52.8 57.8

Mean age at tumor presentation, yrs 53.5 59.5Mean tumor size, cm in CPA† 3.2 2.1Range of tumor size, cm in CPA 2.0–4.5 1.4–2.8Length of follow-up, mos† 30 59

pts = patients.* The combination of paresthesia and neuralgia had 0 pts in the microsurgery or radiosurgery group. † Statistically significant difference.




are summarized in Table 2. Tumor size ≥ 3 cm, age of trigeminal symptom onset ≥ 55 years, and presence of pre-treatment numbness were the pretreatment predictors of persistent TN after microsurgery or GKS. Post-treatment numbness had several predictors, including tumor size ≥ 3 cm, age of trigeminal symptom onset ≥ 55 years, pres-ence of neuralgia prior to treatment, pain medication use before treatment, and previous TN treatment that failed (e.g., glycerol injection).

DiscussionA significant proportion of the existing data regard-

ing the radiosurgical management of tumor-related TN and facial pain is derived from subset analyses of series of benign intracranial tumors treated with SRS.31 In these mixed series, pain and numbness relief rates following SRS have ranged from 33% to 96%,13,24,26,33 and the rate of

persistent TN and trigeminal neuropathy has varied from 1.6% to 36%.2,12,16,25 Paradoxically, many VS SRS series report the onset of new TN or numbness in up to 1%–39% of patients,11,17,20,32 and the radiation dose seems to corre-late with the risk of developing this complication. Patients with VS receiving a < 13-Gy marginal dose are signifi-cantly less likely to develop such pain, paresthesias, or numbness.19,32,35 The large differences in trigeminal symp-tom SRS outcomes are probably related to patient selec-tion bias, variable tumor size exclusion (3–4 cm), failure to systematically inquire about patient symptoms (missing data), and the inclusion of variable marginal radiation dos-ages (12–18 Gy).

Persistent or worsened trigeminal symptoms after SRS are hypothesized to occur from a combination of factors. First, the treatment does not usually shrink the tumor and thus does not relieve the mass effect and compression on the trigeminal nerve. Second, many patients experience a

FIG. 2. Patient-perceived post-treatment neuralgia and paresthesia. FIG. 3. Patient-perceived post-treatment numbness.

FIG. 1. A–C: Left-sided, 4-cm cystic VS resulting in brainstem compression (white arrows) and left facial numbness. The fifth cranial nerve can be seen on thin-slice heavy T2-weighted images (white arrowhead). D–F: Following gross-total resection, the patient reported an improvement in preoperative trigeminal neuropathy and no associated neuralgia. The white arrowhead shows an intact and decompressed trigeminal nerve after tumor resection.


B. A. Neff et al.


transient post-treatment tumor swelling that can lead to a transient or permanent worsening of symptoms.22 Last, it has been postulated that pain and numbness can be permanently exacerbated from direct radiation-induced damage to the trigeminal nerve or the intra-axial trigemi-nal fibers within the pons, because a trigeminal nerve in contact with the tumor capsule will receive a radiation dose approximating the prescribed marginal dose to the tumor.10,30

The fate of trigeminal nerve dysfunction after micro-surgery for VS is even more sparsely reported than radio-surgery treatment series in the existing literature (Table 3). Karkas et al. found that 1 of 3 patients with VS-related TN improved after surgery and that 4 of 29 (14%) patients with facial numbness improved; however, the follow-up of 2 weeks for many patients was exceedingly short.15 It is hypothesized that surgery relieves trigeminal symptoms by removing the mass compression of the nerve. Another hypothesized mechanism for VS-related TN is that the tumor pushes the trigeminal nerve and an artery such as the superior cerebellar artery into contact, thus mimicking the neurovascular etiology seen in the typical TN that is not associated with tumor compression.1,14,29 In our series, the trigeminal nerve was routinely decompressed of as much tumor as possible, and a systematic inspection for a compressive artery was performed. In the vast majority of cases, we did not find that a vascular etiology of neuralgia was present.

To our knowledge, this is the first retrospective pre-treatment TN and trigeminal neuropathy outcomes report, dedicated to only patients with VS, comparing microsur-gery and radiosurgery. Microsurgery was significantly superior to GKS at treating VS and the trigeminal symp-toms. This was so despite a surgical selection bias for tu-mors > 2.5 cm or tumors causing significant mass effect on the brainstem. There were certainly other biases, given that this study did not randomly assign patients; however, the BNI scale outcomes were vastly different in favor of microsurgery. In all patients, the goal going into surgery was total tumor removal.

In cases with preoperative trigeminal symptoms, sub-total tumor resection was performed in 38% of our cases to preserve vital neurovascular structures and function. In nearly all of these cases, tumor remnants were left for facial nerve preservation, and in each subtotal resection,

> 90% of the tumor was removed to provide trigeminal nerve decompression even if a small tumor remnant was left along the trigeminal nerve. In addition, lysis of adhe-sions, if present, was always performed around the fifth cranial nerve as well as vascular decompression if it was believed that there was a vessel compressing the trigemi-nal nerve. Tumor was left along the trigeminal nerve in a minority of cases (4 of 50 [8%]), and only 1 case required a concomitant microvascular decompression.

There were no improvements in pretreatment neural-gia, paresthesias, or numbness in the GKS patient group,

FIG. 4. Bar graph showing results in this study according to the BNI neuralgia scale.

FIG. 5. Bar graph showing results in this study according to the BNI hypesthesia scale.

TABLE 2. Pretreatment predictors of post-treatment TN and hypesthesia

Post-treatment Outcome p Value

TN Predictive Tumor size ≥3 cm 0.0289 Age ≥55 yrs 0.024 Pretreatment numbness 0.024 Not predictive Sex 0.539 Pretreatment paresthesias 0.687 Comorbid headache diagnosis 1.00 Pretreatment use of pain medication 0.718 Failure of other TN treatments (e.g., glycerol injections) 0.718 Cystic tumor 0.091Hypesthesia Predictive Pretreatment neuralgia 0.004 Pretreatment use of pain medication 0.006 Age ≥55 yrs 0.001 Tumor ≥3 cm 0.0216 Failure of other TN treatments 0.009 Not predictive Sex 0.5906 Pretreatment paresthesias 0.302 Comorbid headache diagnosis 0.678 Cystic tumor 0.126




and 2 patients developed new, permanent neuralgia or paresthesias after treatment. There are 2 foreseeable bias factors that could have negatively influenced the GKS outcomes. First, the follow-up was longer for the radiosur-gery group, and thus it could be hypothesized that recur-rence of symptoms might be greater given the longer time period. However, this is unlikely to have influenced our results because none of the patients had temporary relief of symptoms followed by late symptom recurrence. Their symptoms were the same or worse at the first post-treat-ment follow-up, which was usually at 3 months, and the symptoms did not improve over an average of 59 months. Second, 2 patients received a marginal dose of > 13 Gy, which has been shown to increase the rate of post-GKS trigeminal symptoms in other reports.32 However, this still left 8 patients with unimproved symptoms after receiving contemporary dose plans (marginal dose 12–13 Gy).

Several studies have evaluated risk factors or predictors of trigeminal dysfunction after microsurgery and SRS for VS. Premicrosurgical risk factors mentioned in the litera-ture are tumor growth toward the brainstem in an upward direction and tumor cyst formation, although the latter was not statistically correlated with trigeminal nerve symp-toms in this present series.15,29 Conversely, another study failed to elucidate any peri-microsurgery risk factors for post-treatment trigeminal symptoms despite evaluating fifth nerve distortion, compression and nonvisibility of the ipsilateral trigeminal nerve preoperatively, and presence of residual tumor postoperatively.15

Radiosurgery studies have found variable risk factors. A few larger studies identified target volume and maxi-mum dose delivered to the trigeminal nerve as the only pretreatment predictors of adverse trigeminal SRS effects. Tumor volumes > 5 cm3 and a maximum trigeminal dose > 9 Gy had an increasingly greater chance of resultant tri-geminal nerve side effects.8,11 A second study demonstrat-ed that the length of the cranial nerve that was irradiated corresponded to the subsequent neuropathy.7,18 In contrast, a final study highlighted that the brainstem radiation dose

was the most significant predictor of trigeminal neuropa-thy.9,11,27

Our study was slightly different because it evaluated only patients with trigeminal nerve symptoms prior to therapy and then the fate of these symptoms after treat-ment. We identified the following risk factors for persis-tence of trigeminal symptoms in the combined cohort of 60 patients. (There were not enough patients in the SRS cohort to look at the groups separately, and the treatment itself caused poor outcomes that overrode the discovery of any patient factors.) We identified only a few risk factors for persistent post-treatment neuralgia, which were tumor size ≥ 3 cm, age at trigeminal symptom onset ≥ 55 years, and the presence of pretreatment numbness.

There were several risk factors for persistent post-treat-ment trigeminal neuropathy (numbness), which included the following: age at trigeminal symptom onset ≥ 55 years; tumor size ≥ 3 cm; use of pretreatment pain medication; a previous TN procedure that failed (e.g., glycerol injec-tion); and the presence of TN pretreatment. The overall risk of any level of persistent TN after microsurgery and SRS was 61% and 100%, respectively, and the risk of any level of numbness or paresthesias was 64% and 100%, re-spectively. Many of these microsurgery patients indeed had improved neuralgia and numbness/paresthesias (58% and 50%, respectively) despite some residual symptoms; moreover, none of the SRS patients had improvement of any of their trigeminal symptoms.

Patients with any of the identified risk factors should be counseled that their risk is even higher than these aver-ages. Overfitting is a potential weakness of this and any multivariable analysis. Overfitting a regression model can occur when attempting to estimate too many parameters from a small sample size. In other words, it is possible that some statistically significant factors in the regression model may not be significant in a much larger patient pop-ulation. This is because rather than reflecting the overall population, the regression model reflects random noise in a specific sample.

TABLE 3. Summary of recent microsurgery and radiosurgery series of patients with VS and TN

Authors & Year Intervention Findings

Cheng et al., 1993

Microsurgery Mixed population of tumors, which included 10 VSs. It was not clearly presented how many of these 10 pts underwent surgery. There was no report about trigeminal nerve symptom outcomes after surgery for these 10 pts w/ VS.

Samii & Mat-thies, 1995

Microsurgery Reported 9 cases of small VSs where tumor/nerve contact or compression was not believed to be the cause of TN. Vascular compression was found & treated, w/ good results in “most” cases.

Barker et al., 1996

Microsurgery Multiple tumor types in 26 pts. Only 8 pts had VSs with TN. Although their pt cohort reported arterial compression of the trigeminal nerve & significant pain relief w/ tumor removal, they did not report results specific to their 8 pts w/ VS.

Karkas et al., 2014

Microsurgery Among 32 pts who were surgically treated for VS w/ preop trigeminal symptoms, 3/3 had improved neuralgia long term (undefined); 0/1 had improved facial anesthesia; & 4/28 (14%) had improved facial hypesthesia at 10 days.

Pollock et al., 2000

Radiosurgery Study included 26 pts w/ tumors involving the trigeminal nerve w/ TN. All were treated w/ SRS. None of the tumors were VSs. Half of the pts were initially free of pain after treatment, w/ variable follow-up.

Régis et al., 2001

Radiosurgery Study included 53 pts w/ concomitant TN. GKS was used for a mixture of middle and posterior fossa tumors. Sev-enteen patients had VSs. Overall, 78% of pts were free of pain after GKS. The pts w/ VS were not analyzed as a specific group, so results were difficult to analyze or extrapolate.

Huang et al., 2008

Radiosurgery Study included 21 pts w/ TN treated w/ GKS. Only 9 pts had VS. Overall, 57% of pts achieved complete pain relief & no longer required medication. Only 8 pts were treated for VS, of whom 5 had “poor” outcomes w/ pain.


B. A. Neff et al.


ConclusionsTrigeminal neuralgia and trigeminal neuropathy can

rarely be incited by VS-related neural compression. Many of these large tumors are preferentially treated with sur-gery to relieve brainstem compression and hydrocephalus. However, there is a subset of these tumors without brain-stem mass effect, where treatment of the trigeminal symp-toms is a primary goal of the patient and physician. This study demonstrated that microsurgery was significantly better at treating the tumor and improving the trigeminal symptoms compared with SRS, which often exacerbated these preexisting symptoms. Tumor size ≥ 3 cm was the primary predictor of continued difficulty with pain, pares-thesias, and numbness after treatment.

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DisclosuresThe authors report no conflict of interest concerning the materi-als or methods used in this study or the findings specified in this paper.

Author ContributionsConception and design: Neff. Acquisition of data: Neff. Analysis and interpretation of data: Neff, Van Gompel. Drafting the article: Neff, Carlson, Van Gompel. Critically revising the article: Neff, Carlson, Van Gompel, Driscoll, Link. Reviewed submitted version of manuscript: Neff, Carlson, Driscoll, Link. Approved the final version of the manuscript on behalf of all authors: Neff. Statistical analysis: O’Byrne.

Supplemental InformationPrevious PresentationsPresented as an oral presentation at the North American Skull Base Society Meeting, Scottsdale, AZ, February 13, 2016.

CorrespondenceBrian A. Neff, Department of Otorhinolaryngology, Mayo Clinic, 200 First St. SW, Rochester, MN 55905. email: [email protected].


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