McClelland, Robyn L.

Object The cervical foraminotomy was pioneered in the 1940s to address radicular symptoms via a posterior approach, but the long-term outcome has not been adequately studied. Methods The authors retrospectively analyzed data obtained from 303 patients (188 male and 115 female, mean age 49.2 years) who had consecutively undergone a single-level posterior foraminotomy for cervical radiculopathy between 1972 and 1992. The median follow-up duration was 7.1 years. The major end point studied was the development of symptomatic adjacent- or same-segment disease. Incidence rates per 1000 person-years were calculated, and the natural history of the disease was predicted using Kaplan–Meier survivorship analysis. In 15 (4.9%) of 303 patients, symptomatic adjacent-segment disease developed, yielding a rate of 6.4/1000 person-years at risk. This included nine (2.9%) of 303 patients requiring reoperation, yielding a rate of 3.8/1000 person-years. Kaplan–Meier survivorship analysis suggested a relatively stable annual 0.7% rate for developing adjacent-segment disease, with a 10-year rate of 6.7%. Ten patients developed same-segment disease, yielding a risk rate of 3.9/1000 person-years. Kaplan–Meier survivorship analysis demonstrated a 5- and 10-year risk rate of developing same-segment disease of 3.2 and 5.0%, respectively. Conclusions Although additional study is needed, analysis of the present data suggests that posterior foraminotomy is associated with a low rate of same- and adjacent-segment disease.

Background The Detect Supraventricular Tachycardia (Detect SVT) trial was a randomized single blind study in subjects receiving a dual chamber implantable cardioverter defibrillator (ICD). The primary goal was to evaluate whether dual chamber enhancements result in greater discrimination between supraventricular tachycardia (SVT) and ventricular episodes when compared to ventricular-only enhancements. Purpose The purpose of this report is to describe our experiences from an analytic perspective, including overall study design, the value of blinded episode review, and the statistical analysis plan. Methods The Detect SVT study was a parallel group study, with blinded central review of all arrhythmia episodes occurring over a six-month period. The primary response was the proportion of inappropriate detections (SVT episodes that are inappropriately classified as ventricular by the device). Results A parallel group design was essential as unplanned crossovers were very differential. The blinded review of episodes was a major use of resources, with over 2300 episodes observed. This review did not materially alter the findings, however, the avoidance of any perceived bias was a major strength. The value of collecting large numbers of episodes on a single subject was found to be minimal. A Kaplan–Meier analysis of the number of SVT episodes until first inappropriate detection was found to add additional information. Limitations The recommendations reported here relate to cardiac arrhythmia trials, or other studies with very similar endpoints. These observations are based on the results of a single trial and should be confirmed in other studies. Conclusions The parallel group design was essential, as was accounting for within-subject correlation in the analysis. The blinded review process was also important, but significant resources could be saved by closing-out episode collection after a fixed number of episodes. Lessons learned from the Detect SVT trial may prove useful to others designing trials in this active research area.

Background— Delivery of inappropriate shocks caused by misdetection of supraventricular tachycardia (SVT) remains a substantial complication of implanted cardioverter/defibrillator (ICD) therapy. Whether use of optimally programmed dual-chamber ICDs lowers this risk compared with that in single-chamber ICDs is not clear. Methods and Results— Subjects with a clinical indication for ICD (n=400) at 27 participating centers received dual-chamber ICDs and were randomly assigned to strictly defined optimal single- or dual-chamber detection in a single-blind manner. Programming minimized ventricular pacing. The primary end point was the proportion of SVT episodes inappropriately detected from the time of programming until crossover or end of study. On a per-episode basis, 42% of the episodes in the single-chamber arm and 69% of the episodes in the dual-chamber arm were due to SVT. Mortality (3.5% in both groups) and early study withdrawal (14% single-chamber, 11% dual-chamber) were similar in both groups. The rate of inappropriate detection of SVT was 39.5% in the single-chamber detection arm compared with 30.9% in the dual-chamber arm. The odds of inappropriate detection were decreased by almost half with the use of the dual-chamber detection enhancements (odds ratio, 0.53; 95% confidence interval, 0.30 to 0.94; P =0.03). Conclusions— Dual-chamber ICDs, programmed to optimize detection enhancements and to minimize ventricular pacing, significantly decrease inappropriate detection.

ABSTRACT OBJECTIVE Remote cerebellar hemorrhage (RCH) is an infrequent and poorly understood complication of supratentorial neurosurgical procedures. We retrospectively compared 42 patients who experienced RCH with a case-matched control cohort, to delineate risk factors associated with the occurrence of this complication. METHODS Between 1988 and 2000, 42 patients experienced RCH after supratentorial neurosurgical procedures at our institution. Diagnoses were made on the basis of postoperative computed tomographic or magnetic resonance imaging findings in all cases. The medical records for these patients were reviewed and compared with those for a control cohort of 43 patients, matched for age, sex, surgical lesion, and type of craniotomy, who were treated during the same period. RESULTS RCH most commonly occurred after frontotemporal craniotomies for unruptured aneurysm repair or temporal lobectomy and was frequently an incidental finding on postoperative computed tomographic scans. However, some cases of RCH were associated with significant morbidity, and two patients died. Preoperative aspirin use and elevated intraoperative systolic blood pressure were significantly associated with RCH (P = 0.026 and P = 0.036, respectively). Pathological findings for two cases demonstrated hemorrhagic infarctions in both. CONCLUSION RCH most commonly follows supratentorial neurosurgical procedures, performed with the patient in the supine position, that involve opening of cerebrospinal fluid cisterns or the ventricular system (such as unruptured aneurysm repair or temporal lobectomy). Preoperative aspirin use and moderately elevated intraoperative systolic blood pressure are potentially modifiable risk factors associated with the development of RCH. Although RCH can cause death or major morbidity, most cases are asymptomatic or exhibit a benign course. Cerebellar “sag” as a result of cerebrospinal fluid hypovolemia, causing transient occlusion of superior bridging veins within the posterior fossa and consequent hemorrhagic venous infarction, is the most likely pathophysiological cause of RCH.

Background and Purpose— Internal carotid artery (ICA) occlusion is an important cause of transient ischemic attack (TIA) and cerebral infarction. There are no previous population-based natural history studies evaluating outcome after symptomatic ICA occlusion (SICAO). Methods— We performed a retrospective, population-based study of SICAO. All Olmsted County (Minnesota) residents with possible SICAO from 1986 to 2000 were identified by cross-referencing appropriate clinical and imaging codes. Inclusion criteria were cerebral infarction or TIA in a carotid distribution and imaging documentation of ipsilateral ICA occlusion <3 months after the index event. Kaplan–Meier estimates were used to calculate the risk of cerebral infarction, myocardial infarction, and death after SICAO. Results— Seventy-five patients qualified. Annual SICAO incidence was 6 per 100 000 persons (age and gender adjusted to the 2000 US white population). Risk of cerebral infarction during follow-up was 8% at 30 days, 10% at 1 year, and 14% at 5 years. Five of 11 cerebral infarctions occurred within the first week after diagnosis of occlusion. Risk of myocardial infarction was 0% at 30 days, 8% at 1 year, and 24% at 5 years. Risk of death was 7%, 13%, and 29%, respectively. Conclusions— There may be 15 000 to 20 000 incident cases of SICAO in the United States annually. Risk of cerebral infarction after SICAO is initially high and then stabilizes, whereas risk of myocardial infarction is initially low but gradually increases. Better strategies are needed to reduce early stroke recurrence in this setting.

Background— Clinical and radiologic predictors of cerebral infarction occurrence and location after aneurysmal subarachnoid hemorrhage have been seldom studied. Methods— We evaluated all patients admitted to our hospital with aneurysmal subarachnoid hemorrhage between 1998 and 2000. Cerebral infarction was defined as a new hypodensity located in a vascular distribution on computed tomography (CT) scan. Results— Fifty-seven of 143 patients (40%) developed a cerebral infarction. On univariate analysis, occurrence of cerebral infarction was associated with a worse World Federation of Neurological Surgeons grade ( P =0.01), use of ventriculostomy catheter ( P =0.01), preoperative vasospasm ( P =0.03), surgical clipping ( P =0.02), symptomatic vasospasm ( P <0.01), and vasospasm on transcranial Doppler ultrasonography (TCD) or repeat angiogram ( P <0.01). On multivariable analysis, only presence of symptoms ascribed to vasospasm ( P <0.01) and evidence of vasospasm on TCD or angiogram predicted cerebral infarction ( P <0.01). TCD and angiogram agreed on the diagnosis of vasospasm in 73% of cases (95% CI, 63% to 81%), but the diagnostic accuracy of this combination of tests was suboptimal for the prediction of cerebral infarction occurrence (sensitivity, 0.72; specificity, 0.68; positive predictive value, 0.67; negative predictive value, 0.72). Location of the cerebral infarction on delayed CT was predicted by neurological symptoms in 74%, by aneurysm location in 77%, and by angiographic vasospasm in 67%. Conclusions— Evidence of vasospasm on TCD and angiogram is predictive of cerebral infarction on CT scan but sensitivity and specificity are suboptimal. Cerebral infarction location cannot be predicted in one quarter to one third of patients by any of the studied clinical or radiological variables.