See the corresponding editorial in this issue, p 201. J Neurosurg 115: , 2011

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1 See the corresponding editorial in this issue, p 201. J Neurosurg 115: , 2011 Safety of microvascular decompression for trigeminal neuralgia in the elderly Clinical article Anand I. Rughani, M.D., Travis M. Dumont, M.D., Chih-Ta Lin, M.D., Bruce I. Tranmer, M.D., and Michael A. Horgan, M.D. Division of Neurosurgery, University of Vermont, Burlington, Vermont Object. Microvascular decompression (MVD) offers an effective and durable treatment for patients suffering from trigeminal neuralgia (TN). Because the disorder has a tendency to occur in older persons, the risks of surgical treatment in the elderly have been a topic of recent interest. To date, evidence derived from several small retrospective and a single prospective case series has suggested that age does not increase the complication rate associated with surgery. Using a large national database, the authors aimed to study the impact of age on in-hospital complications following MVD for TN. Methods. Using the Nationwide Inpatient Sample (NIS) for the 10-year period from 1999 to 2008, the authors selected all patients who underwent MVD for TN. The primary outcome of interest was the in-hospital mortality rate. Secondary outcomes of interest were cardiac, pulmonary, thromboembolic, cerebrovascular, and wound complications as well as the duration of hospital stay, total hospital charges, and discharge location. An elderly cohort of patients was first defined as those 65 years of age and older and then redefined as those 75 years and older. Results. A total of 3273 patients who underwent MVD for TN were identified, having a median age of 57 years. Within this sample, 31.5% were 65 years and older and 10.7% were 75 years and older. The in-hospital mortality rate was 0.68% for patients 65 years or older (p = ) and 1.16% for those 75 years or older (p = ). In patients younger than 65 years, the in-hospital mortality rate was 0.13% (3 deaths among 2241 patients). As analyzed using the chi-square test (for both 65 and 75 years as the age cutoff) and the Pearson rank correlation coefficient, the risk of cardiac, pulmonary, thromboembolic, and cerebrovascular complications was higher in older patients (that is, those 65 and older and those 75 and older), but the risks of wound complications and CNS infection were not. The risk of any in-hospital complication occurring in a patient 65 years and older was 7.36% (p < ) and 10.0% in those 75 years and older (p < ). There was no difference in the total hospital charges associated with age. The duration of the hospital stay was longer in older patients, and the likelihood of discharge home was lower in older patients. Conclusions. Microvascular decompression for TN in the elderly population remains a reasonable surgical option. However, based on data from a large national database, authors of the present study suggest that complications do tend to gradually increase in tandem with an advanced age. While age does not act as a risk factor in isolation, it may serve as a convenient surrogate for complication rates. The authors hope that this information can be of use in guiding older patients through decisions for the surgical treatment of TN. (DOI: / JNS101924) Key Words complication craniotomy facial pain trigeminal neuralgia pain Abbreviations used in this paper: LOS = length of stay; MVD = microvascular decompression; NIS = Nationwide Inpatient Sample; TN = trigeminal neuralgia. Since its description by Jannetta,10,11 MVD has proven to be a successful surgical treatment for TN. As the incidence of TN increases with age, 17 the safety of MVD in the elderly population represents an important clinical question for treating physicians. Several small studies, 2,8,9,12,13,25,27,30 including a recent prospective analysis, 29 have suggested that the efficacy and safety of MVD in elderly patients are comparable with those in younger patients. Unfortunately these studies are limited by small sample sizes. Utilizing a large national data set, we determined that the impact of an advanced age on perioperative complication rates associated with MVD for TN could be better elucidated. Methods The NIS was obtained from the Agency for Healthcare Research and Quality for the years from 1999 to The NIS represents the largest database of hospital admissions in the US, includes all payers, and with approximately 8 million entries per year it accounts for a stratified sample of about 20% of all inpatient admissions. For the year 2008, the NIS contains data obtained from 1056 hospitals in 42 states. Patients were selected 202 J Neurosurg / Volume 115 / August 2011

2 Microvascular decompression in the elderly for inclusion in our analysis if they had ICD-9 codes for a principle diagnosis of TN (350.1) and a principle procedure of MVD (04.41). Only in-hospital complications are captured with this database. The primary outcome measure was the in-hospital mortality rate. Secondary outcome measures included medical complications, duration of hospital stay, total hospital charges, and discharge location. The NIS allows for coding up to 14 diagnoses in addition to the principle diagnosis. In-hospital complications were identified by searching for ICD-9 codes that would be representative of acute postoperative complications and not preexisting conditions. Individual complications were selected with care to include only acute illnesses. Categories included cardiac, pulmonary, thromboembolic, and cerebrovascular disease, CNS infection, and wound complication. Table 1 features the categories of complications and the specific ICD-9 codes selected for each category. Initial assessment also included cranial nerve injury ( ) and cerebellar laceration or contusion ( ), but because only one instance of each was recorded, these categories were not further analyzed. The risk of any complication occurring was also calculated if any category was positive for a single patient. The initial analysis consisted of a graphic representation of individual complication rates according to the patient decade of life. For each category of complication a Spearman rank correlation coefficient was calculated for patient age and complication rate to determine whether age could be correlated with the risk of each complication category. We then divided the population into an elderly cohort and nonelderly cohort. The age used to define the elderly population has varied across publications, 29 ranging from 60 to 75 years, and therefore, we used 2 different age cutoffs to distinguish our elderly population. The data were analyzed using an age cutoff of 65 years and then reanalyzed with an age cutoff of 75 years. Data were analyzed with SAS 9.2 (SAS Institute, Inc.) and GraphPad Prism 5.0 (GraphPad Software, Inc.). Using a 2-tailed Pearson chi-square test, the risk of each complication was assessed for the elderly cohort as compared with the nonelderly cohort. A 2-tailed Student t-test was used to compare the groups with regard to total LOS and total hospital charges. Results We identified 3273 patients within the NIS who underwent MVD as the primary procedure for a principle diagnosis of TN during the 10-year interval between 1999 and Figure 1 demonstrates the age composition of this cohort by decade, with ages ranging from 6 to 93 years and a median age of 57 years. Patients 65 years and older comprised 31.5% of the sample, whereas those 75 years and older comprised 10.7% of the sample. We analyzed the risks of MVD in the elderly according to the 2 different age cutoffs for distinguishing elderly and nonelderly patients. The initial analysis was performed to compare the cohort of 2241 patients under the age of 65 years with the cohort of 1032 patients 65 years and older. These results are presented first, followed by a reanalysis J Neurosurg / Volume 115 / August 2011 in which the 2923 patients under the age of 75 years were compared with the 350 patients 75 years and older. Age Cutoff: 65 Years The in-hospital mortality rate did rise with an increased age (Fig. 2A) and was 0.13% for patients younger than 65 years compared with 0.68% for those 65 years and older (p = ). The odds ratio of an in-hospital death among patients with an age 65 years compared with an age < 65 years was 5.1 (95% CI ). An increased age was associated with an elevated risk of cardiac complications (from 0.45% to 1.94%, p = ; Fig. 2B), pulmonary complications (from 1.07% to 2.23%, p < ; Fig. 2C), thromboembolic complications (from 0.27% to 1.16%, p = ; Fig. 2D), and cerebrovascular complications (from 1.38% to 3.29%, p = ; Fig. 2E). Increased age was not associated with a difference in the incidence of CNS infection (from 0.27% to 0.39%, p = ; Fig. 2F) or wound complications (from 0.13% to 0.19%, p = ; Fig. 2G). The incidence of any single complication occurring did increase with age (from 3.26% to 7.36%, p < ; Fig. 2H). The average hospital LOS was shorter in patients younger than 65 years at 3.3 days compared with 4.0 days in patients 65 years or older (p < ; Fig. 3 left). There was no difference in the total hospital charges, which averaged $34,583 in the younger cohort compared with $36,035 in the older cohort (p = ; Fig. 3 right), although when examined across all ages a statistically significant correlation was identified. Complications among patients 65 years and older are summarized in Fig. 4 left. Age Cutoff: 75 Years When reanalyzed using 75 years as the age cutoff, there were slight changes in the incidences of various complications, but there was no category in which statistical significance was appreciably shifted. For all patients younger than 75 years, the in-hospital mortality rate was 0.21% compared with 1.16% for those 75 years and over (p = ; Fig. 2A). The odds ratio of an in-hospital death for patients 75 years and older compared with patients younger than 75 years was 5.6 (95% CI ). An increased age was associated with an elevated risk of cardiac (from 0.79% to 2.00%, p = ; Fig. 2B), pulmonary (from 1.13% to 4.00%, p < ; Fig. 2C), thromboembolic (from 0.38% to 2.00%, p < ; Fig. 2D), and cerebrovascular complications (from 1.74% to 4.00%, p = ; Fig. 2E). An older age was not associated with a difference in the incidence of CNS infection (from 0.14% to 0%, p = ; Fig. 2F) or wound complications (from 0.14% to 0.29%, p = ; Fig. 2G). The incidence of any single complication occurring increased with age (from 3.90% to 10.0%, p < ; Fig. 2H). The average LOS was shorter in patients younger than 75 years at 3.4 days compared with 4.3 days in patients 75 years or older (p < ; Fig. 3 left). There was no difference in the total hospital charges, which averaged $35,032 in the younger cohort compared with $35,105 in the older cohort (p = ; Fig. 3 right). Complications among patients 75 years and older are summarized in 203

3 A. I. Rughani et al. TABLE 1: Medical and surgical complications queried according to ICD-9 code* Complication ICD-9-CM cardiac acute myocardial infarction 410 cardiac arrest acute CHF, systolic acute on chronic CHF, systolic acute CHF, diastolic acute on chronic CHF, diastolic acute CHF, systolic & diastolic acute on chronic CHF, systolic & diastolic cardiac complication of medical/surgical care pulmonary acute bronchitis & bronchiolitis pneumonia pneumothorax 512 pulmonary insufficiency after surgery acute respiratory failure other pulmonary insufficiency respiratory complication of medical/surgical care thromboembolic acute pulmonary heart disease 415 phlebitis & thrombophlebitis 451 other venous embolism & thrombosis 453 stroke intracerebral hemorrhage 431 nervous system complication of medical/surgical care hemorrhage complicating a procedure CNS infection bacterial meningitis 320 meningitis due to other organism 321 meningitis of unspecified cause 322 intracranial & intraspinal abscess 324 wound disruption of wound postop infection miscellaneous cerebellar laceration or contusion cranial nerve injury * CHF = congestive heart failure. Fig. 4 right. Table 2 summarizes the complication rates in older patients according to the 2 different age cutoffs. As illustrated in Fig. 5 a strong relationship was identified between age and a decreased likelihood of discharge to home. A nearly linear Spearman correlation coefficient of 0.96 was revealed (p < 0.01). In-Hospital Mortality Rate Table 3 summarizes the in-hospital deaths and lists the patient ages, which average 70.8 years. In-hospital Fig. 1. Bar graph representing the age distribution of the 3273 patients included in our analysis. Octogenarians represent 4.3% of the sample, septuagenarians 16.0%, and sexagenarians 23.9%. deaths were further analyzed using the ICD-9-CM codes for secondary diagnoses to gain insight into the causes of death. Sufficient information was coded to ascertain the conditions associated with death in 9 of 10 patients. The most common cause of in-hospital death appeared to be iatrogenic hemorrhage, documented in 3 patients. There was one clearly coded ischemic stroke. Four additional patients had either a stroke or hemorrhage, without enough specificity in the ICD-9 codes to distinguish. Two patients had acute myocardial infarction without any mention of surgical or cerebrovascular complications. Among the patients who died, 4 had undergone placement of a ventriculostomy and 2 underwent reopening of the craniotomy site. In short, 2 of the 10 deaths seem very likely attributable to underlying systemic or cardiac disease and 7 of the 10 patients had a cerebrovascular complication, either ischemic or hemorrhagic. Discussion Trigeminal neuralgia is a disabling condition tending to occur in older persons, 16 with a mean age of 51.5 years at diagnosis. 17 Failing adequate control with medication, treatment consists of various surgical options, which include percutaneous ablative procedures, 34 stereotactic radiosurgery, 18 and craniotomy for MVD. Microvascular decompression has proven to be a particularly effective mode of treatment, with some studies reporting as many as 98% of patients with typical TN obtaining some pain relief immediately postoperatively and up to 80% obtaining complete relief immediately following surgery. 3,22,32 As the world s population ages, the safety of MVD in older persons has become a topic of increased interest. 2,8,9,12,13,25,27,29,30 To date, the safety of MVD in older patients has been examined through several small case series, which were 204 J Neurosurg / Volume 115 / August 2011

4 Microvascular decompression in the elderly Fig. 2. Graphs showing complication rates trended against age stratified by decade for patients years. Recorded complications include in-hospital death (A), acute cardiac complications (B), acute pulmonary complications (C), thromboembolic complications (D), cerebrovascular complications (E), CNS infections (F), wound complications (G), and any single complication (H). Error bars represent the standard error of the mean. In each panel, the value r s represents the Spearman rank correlation coefficient, with the associated p value. Fig. 3. Bar graphs demonstrating the average hospital LOS (left) and total hospital charges (right). Error bars represent the standard error of the mean, and r s represents the Spearman rank correlation coefficient, with the associated p value. There was a statistically significant correlation between patient age and LOS, but there was not a correlation between patient age and total hospital charges. J Neurosurg / Volume 115 / August

5 A. I. Rughani et al. Fig. 4. Graphs showing individual complications compared by age stratification according to 2 different age cutoffs, 65 years (left) and 75 years (right), where a Pearson chi-square test was used to assess the difference between those under and those at or over each age cutoff. Switching the age cutoff from 65 to 75 years did not alter statistical significance. With the exception of meningitis and wound complication, the complication rates were significantly higher in the older cohort, that is, those 65 and older and those 75 and older. recently summarized in a meta-analysis by Sekula and colleagues. 29 With the exception of a recent contribution by those authors, these studies collectively consist of retrospective comparisons of small cohorts ranging in size from 8 to 117 elderly patients. Authors of these studies have compared groups of older and younger patients defined by an arbitrary age cutoff. The age cutoffs range from 60 years in 1 study, 2 65 years in 4 studies, 8,9,25 70 years in 1 study, 12 to 75 years in 2 studies. 27,30 Cumulatively, these studies examine 441 older patients, with attention to multiple complications including death, stroke, cerebellar hematoma, cranial nerve injury, CSF leak, and infection. Authors of these studies independently report that older patients do not have an increased risk of death, stroke, cerebellar hematoma, or cranial neuropathy, and this conclusion remains when analyzed collectively through a meta-analysis. 29 As previously emphasized by Burchiel, 6 these small series may not have adequate statistical power to capture the effects of age on morbidity and death associated with this surgical procedure. The present study takes advantage of a large data set that provides a representative national sample over a 10-year period. The statistical advantage of this work is offset by several limitations inherent to utilizing an administrative database. In addition to the limited clinical and radiographic information as well as the limits of data abstraction by medical coders, the principal limitation of this approach lies in the incomplete follow-up. Thus, it must be emphasized that the complication rates ascertained in the present study fail to capture delayed complications. While the complication rates presented here may be an underestimate because of this shortcoming, it may be especially true with regard to certain complications. The complications more prone to a delayed presentation can include thromboembolic complications, CSF leaks, wound complications, and infections. It also remains possible that certain complications are over-coded by data abstractors. Perhaps a postoperative CT demonstrating a small, clinically silent hemorrhage is recorded as an intracranial hemorrhage. Even if over-coding does occur, it would be reasonable to assume that it happens independently of the patient age. Ashkan and Marsh 2 provide a comprehensive summary of published mortality data (their Table 4), which when summed consist of 4621 patients across 28 studies and a total of 20 reported deaths, for a mortality rate of 0.4%. In the present study, we noted a 0.3% overall mortality rate (10 deaths in 3272 patients), which is not statistically different from the rate reported by Ashkan and Marsh (p = ). The in-hospital mortality rate in our study probably represents a slight underestimate of the true perioperative rate because it fails to capture those deaths and complications that occurred after discharge. When examining the causes of death in our sample, there was probably a bias toward acute complications, which among the 10 deaths appear to consist of 2 acute cardiac events and up to 7 acute postoperative strokes or hemorrhages. Overall, our estimate and the rate in the published literature seem quite consistent, and for all ages it should be safe to consider the mortality rate associated with MVD to be < 0.5%. In addition to the in-hospital mortality rate, we identified a strong relationship between age and cardiac, pulmonary, thromboembolic, and cerebrovascular compli- TABLE 2: In-hospital complication rates according to age cutoff Complication Patients Over 65 Yrs (%) Patients Over 75 Yrs (%) in-hospital death cardiac pulmonary thromboembolic cerebrovascular CNS infection wound complication any complication J Neurosurg / Volume 115 / August 2011

6 Microvascular decompression in the elderly Fig. 5. Graph showing discharge to a location other than home, according to age. Error bars represent the standard error of the mean. Spearman rank correlation coefficient is represented by r s, with the associated p value. cations. When analyzed with a chi-square test, the significance did not differ appreciably when the age cutoff was changed between 65 and 75 years. What is illustrated graphically in Fig. 2 and statistically with the Spearman rank correlation coefficient is a gradual and progressive increase in the risk of complications associated with an increased age. Although necessary for statistical analysis, there is little utility in drawing arbitrary distinctions among patient populations based on age. As discussed by Burchiel, 6 patient selection and counseling relies on the thoughtful recognition of the risks harbored by each patient. Furthermore, it must be recognized that age serves simply as a surrogate for risk, where age itself is not necessarily the primary determinant of complications but instead is correlated with other variables such as comorbid conditions and even hospital and surgeon volume. 14 Although it has been alluded to by other authors, 21 it is not our intent to suggest that age itself should be used as a determinant for or against surgery, but rather that age in conjunction with other factors may help in adequately counseling patients regarding the risks of MVD. Patients suffering from TN should be enabled to make an informed decision regarding treatment options, which also include less invasive albeit less durable methods. The risks associated with percutaneous radiofrequen cy rhizotomy, percutaneous glycerol rhizolysis, percutaneous balloon compression, and stereotactic radiosurgery are reported primarily as delayed complications and treatment failures. Radiofrequency rhizotomy is reported to offer initial rates of complete pain relief ranging from 92% to 98% 15,28 and lasting effects in 58% 64% of patients at 3 years after treatment. 26,36 The principle complications associated with this mode of treatment include loss of the corneal reflex in 9.6% of patients, masseter muscle dysfunction in 11.9%, and painful dysesthesia in 3.7%. 19 Percutaneous glycerol rhizolysis can be expected to lead to complete pain relief in 80% 96% of patients initially 2,35 and sustained relief in 53% 54% of patients at 3 years after treatment. 24,33 The principle complications associated with glycerol rhizolysis include dysesthesias in 8.3% of patients, corneal numbness in 8.1%, and masseter dysfunction in 3.1%. 19 Balloon compression may lead to initial pain relief in 79% 96% of patients 1,4 and lasting effects in perhaps 69% at 3 years after treatment. 5 Balloon compression has been associated with dysesthesia in 10.0% of patients. 19 Stereotactic radiosurgery has been reported to offer early pain relief in up to 81% 7 of patients and sustained pain relief in 34% 56% of patients at 3 years after treatment. 20,31 Principle complications associated with radiosurgery include dysesthesias in 9.2% of patients and corneal numbness in 2.6% of patients. 19 It is worth noting that there are no reports of periprocedural deaths associated with percutaneous methods or radiosurgery. The distinct complication profiles associated with radiosurgery and percutaneous procedures may not facilitate optimal comparison with MVD, but may enable patients to make informed decisions. Although it is beyond the scope of this paper to propose a treatment algorithm for elderly patients, the increased mortality rate associated with MVD in older patients can be considered when making treatment decisions. While some patients may find radiosurgery and percutaneous methods more attractive in light of the possibility of MVD-related death, others may be deterred by the higher failure rates of the less invasive procedures. TABLE 3: Clinical characteristics associated with in-hospital deaths* Age (yrs) Sex Additional Diagnosis Additional Surgical Procedure LOS (days) 55 M coma none 4 56 F intracerebral hemorrhage none 2 61 M intracerebral hemorrhage EVD; reexploration craniotomy 1 65 F iatrogenic CVA or hemorrhage EVD 5 72 F iatrogenic CVA or hemorrhage; brain compression other craniotomy F acute myocardial infarction none 3 78 M coma reexploration of craniotomy 4 78 F acute myocardial infarction none 5 82 M ischemic stroke; hydrocephalus EVD 2 89 F hemorrhage complicating procedure EVD 3 * CVA = cerebrovascular accident; EVD = external ventricular drain. J Neurosurg / Volume 115 / August

7 A. I. Rughani et al. We hope that this work will help to counsel patients about the potential in-hospital risks associated with surgery rather than simply to discourage treatment. In summary, in patients 65 years and older an overall in-hospital complication rate of about 7% and an in-hospital mortality rate of about 0.7% can be estimated. In patients 75 years and older an in-hospital complication rate of about 10% and an in-hospital mortality rate of about 1% can be estimated. Conclusions Microvascular decompression has been regarded as a highly effective and durable treatment for TN. Given TN s predisposition to affect elderly patients and given the aging of the population, the safety of MVD in the elderly deserves consideration. To date, several small case series have suggested that age does not increase the risk associated with MVD in elderly patients. Having taken advantage of a large national data set, we suggest that there is a relationship between advanced age and the risks of in-hospital death as well as cardiac, pulmonary, thromboembolic, and cerebrovascular complications. We hope that this information will help surgeons more accurately guide patients. Disclosure The authors report no conflict of interest concerning the materials or methods used in this study or the findings specified in this paper. Author contributions to the study and manuscript preparation include the following. Conception and design: Rughani. Acquisition of data: Rughani. Analysis and interpretation of data: Rughani, Dumont. Drafting the article: Rughani, Dumont, Lin. Critically revising the article: Rughani, Dumont, Lin. Statistical analysis: Rughani. Administrative/technical/material support: Tranmer, Horgan. References 1. 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8 Microvascular decompression in the elderly 27. Ryu H, Yamamoto S, Sugiyama K, Yokota N, Tanaka T: Neurovascular decompression for trigeminal neuralgia in elderly patients. Neurol Med Chir (Tokyo) 39: , Scrivani SJ, Keith DA, Mathews ES, Kaban LB: Percutaneous stereotactic differential radiofrequency thermal rhizotomy for the treatment of trigeminal neuralgia. J Oral Maxillofac Surg 57: , Sekula RF Jr, Frederickson AM, Jannetta PJ, Quigley MR, Aziz KM, Arnone GD: Microvascular decompression for elderly patients with trigeminal neuralgia: a prospective study and systematic review with meta-analysis. Clinical article. J Neurosurg 114: , Sekula RF, Marchan EM, Fletcher LH, Casey KF, Jannetta PJ: Microvascular decompression for trigeminal neuralgia in elderly patients. J Neurosurg 108: , Sheehan J, Pan HC, Stroila M, Steiner L: Gamma knife surgery for trigeminal neuralgia: outcomes and prognostic factors. J Neurosurg 102: , Sindou M, Leston J, Decullier E, Chapuis F: Microvascular decompression for primary trigeminal neuralgia: long-term effectiveness and prognostic factors in a series of 362 consecutive patients with clear-cut neurovascular conflicts who underwent pure decompression. J Neurosurg 107: , Slettebø H, Hirschberg H, Lindegaard KF: Long-term results after percutaneous retrogasserian glycerol rhizotomy in patients with trigeminal neuralgia. Acta Neurochir (Wien) 122: , Sweet WH: Percutaneous methods for the treatment of trigeminal neuralgia and other faciocephalic pain; comparison with microvascular decompression. Semin Neurol 8: , Waltz TA, Dalessio DJ, Copeland B, Abbott G: Percutaneous injection of glycerol for the treatment of trigeminal neuralgia. Clin J Pain 5: , Zakrzewska JM, Jassim S, Bulman JS: A prospective, longitudinal study on patients with trigeminal neuralgia who underwent radiofrequency thermocoagulation of the Gasserian ganglion. Pain 79:51 58, 1999 Manuscript submitted November 20, Accepted April 13, Please include this information when citing this paper: published online May 13, 2011; DOI: / JNS Address correspondence to: Anand I. Rughani, M.D., Division of Neurosurgery, University of Vermont, 111 Colchester Avenue, Fletcher 507, Burlington, Vermont anand.rughani@ mail.mcgill.ca. J Neurosurg / Volume 115 / August