Microbial metabolomic responses to changes in temperature and salinity along the western Antarctic Peninsula.

Seasonal cycles within the marginal ice zones in polar regions include large shifts in temperature and salinity that strongly influence microbial abundance and physiology. However, the combined effects of concurrent temperature and salinity change on microbial community structure and biochemical composition during transitions between seawater and sea ice are not well understood. Coastal marine communities along the western Antarctic Peninsula were sampled and surface seawater was incubated at combinations of temperature and salinity mimicking the formation (cold, salty) and melting (warm, fresh) of sea ice to evaluate how these factors may shape community composition and particulate metabolite pools during seasonal transitions. Bacterial and algal community structures were tightly coupled to each other and distinct across sea-ice, seawater, and sea-ice-meltwater field samples, with unique metabolite profiles in each habitat. During short-term (approximately 10-day) incubations of seawater microbial communities under different temperature and salinity conditions, community compositions changed minimally while metabolite pools shifted greatly, strongly accumulating compatible solutes like proline and glycine betaine under cold and salty conditions. Lower salinities reduced total metabolite concentrations in particulate matter, which may indicate a release of metabolites into the labile dissolved organic matter pool. Low salinity also increased acylcarnitine concentrations in particulate matter, suggesting a potential for fatty acid degradation and reduced nutritional value at the base of the food web during freshening. Our findings have consequences for food web dynamics, microbial interactions, and carbon cycling as polar regions undergo rapid climate change.

Large Diversity in Nitrogen- and Sulfur-Containing Compatible Solute Profiles in Polar and Temperate Diatoms.

Intense bottom-ice algal blooms, often dominated by diatoms, are an important source of food for grazers, organic matter for export during sea ice melt, and dissolved organic carbon. Sea-ice diatoms have a number of adaptations, including accumulation of compatible solutes, that allows them to inhabit this highly variable environment characterized by extremes in temperature, salinity, and light. In addition to protecting them from extreme conditions, these compounds present a labile, nutrient-rich source of organic matter, and include precursors to climate active compounds (e.g., dimethyl sulfide [DMS]), which are likely regulated with environmental change. Here, intracellular concentrations of 45 metabolites were quantified in three sea-ice diatom species and were compared to two temperate diatom species, with a focus on compatible solutes and free amino acid pools. There was a large diversity of metabolite concentrations between diatoms with no clear pattern identifiable for sea-ice species. Concentrations of some compatible solutes (isethionic acid, homarine) approached 1 M in the sea-ice diatoms, Fragilariopsis cylindrus and Navicula cf. perminuta, but not in the larger sea-ice diatom, Nitzschia lecointei or in the temperate diatom species. The differential use of compatible solutes in sea-ice diatoms suggests different adaptive strategies and highlights which small organic compounds may be important in polar biogeochemical cycles.

Adaptive signals in algal Rubisco reveal a history of ancient atmospheric carbon dioxide.

Rubisco, the most abundant enzyme on the Earth and responsible for all photosynthetic carbon fixation, is often thought of as a highly conserved and sluggish enzyme. Yet, different algal Rubiscos demonstrate a range of kinetic properties hinting at a history of evolution and adaptation. Here, we show that algal Rubisco has indeed evolved adaptively during ancient and distinct geological periods. Using DNA sequences of extant marine algae of the red and Chromista lineage, we define positive selection within the large subunit of Rubisco, encoded by rbcL, to occur basal to the radiation of modern marine groups. This signal of positive selection appears to be responding to changing intracellular concentrations of carbon dioxide (CO(2)) triggered by physiological adaptations to declining atmospheric CO(2). Within the ecologically important Haptophyta (including coccolithophores) and Bacillariophyta (diatoms), positive selection occurred consistently during periods of falling Phanerozoic CO(2) and suggests emergence of carbon-concentrating mechanisms. During the Proterozoic, a strong signal of positive selection after secondary endosymbiosis occurs at the origin of the Chromista lineage (approx. 1.1 Ga), with further positive selection events until 0.41 Ga, implying a significant and continuous decrease in atmospheric CO(2) encompassing the Cryogenian Snowball Earth events. We surmise that positive selection in Rubisco has been caused by declines in atmospheric CO(2) and hence acts as a proxy for ancient atmospheric CO(2).

Secondary gain influences the outcome of lumbar but not cervical disc surgery.

BACKGROUND: The expectation of monetary compensation has been associated with poor outcomes in lumbar discectomy, fueling a reluctance among surgeons to treat worker's compensation cases. This issue, however, has not been investigated in patients undergoing cervical disc surgery. This study analyzes the relationship between economic forms of secondary gain and surgical outcome in a group of patients with common pay scales, retirement plans, and disability programs. METHODS: All procedures were performed at the Portsmouth Naval Medical Center between 1993 and 1995; active duty military servicepersons who were treated for cervical radiculopathy were prospectively included. Clinical, demographic, and financial factors were analyzed to determine which were predictive for outcome. Financial data were used to create a compensation incentive (CI) which is proportional to the rank, years of service, potential disability, retirement eligibility, and base pay and reflects the monetary incentive of disability. The results of cervical surgery were compared to a previously reported companion population of patients treated for lumbar disc disease. A good outcome is defined as a return to active duty, whereas a referral for disability is considered a poor surgical result. RESULTS: One hundred percent follow-up was obtained for 269 patients who were treated with 307 cervical operations. Only 16% (43/269) of cervical patients received disability, whereas 24.7% (86/348) of lumbar patients obtained a poor result (p = 0.0082). Although economic forms of secondary gain were not associated with outcome in cervical disease, both the position (p = 0.002) and duration of an individual's military career were significant factors (p = 0.02). Of the medical variables tested, multilevel surgery (p = 0.03) and revision operations at the same level (p = 0.03) were associated with referral for medical discharge. CONCLUSIONS: Secondary gain in the form of economic compensation influences outcome in lumbar but not cervical disc surgery; this observation may in part account for the success of cervical surgery relative to lumbar discectomy. Social factors that are independent of the anticipation of economic compensation seem to influence the outcome of cervical disc surgery.

Multi-dose crystalloid cardioplegia preserves intracellular sodium homeostasis in myocardium.

The goal of this study was to assess the effect of multi-dose St Thomas' cardioplegia on intracellular sodium homeostasis in a rat heart model. A new magnetic resonance method was applied which enable us to detect intracellular Na changes without chemical shift reagents. Three groups of isolated rat hearts were subjected to 51 min of ischemia and 51 min of reperfusion at 37 degrees C: Group 1-three infusions of St Thomas' cardioplegia every 17 min for 2 min (n=7); Group 2-single-dose infusion of cardioplegia at the beginning of stop-flow ischemia (n=8); and Group 3-clamp ischemia (n=3) without cardioplegia administration. Performance of the heart was assessed by rate-pressure product relative to the pre-ischemic level (RPP). An NMR method was applied which continuously detects the Na(i) concentration in the heart, using the ability of bound sodium to exhibit triple-quantum transitions and the growth of the corresponding signal when sodium ions pass from extracellular to intracellular space. Clamp ischemia without cardioplegia and 50 min of reperfusion left the heart dysfunctional, with Na(i) growth from the pre-ischemic level of 13.9+/-1.2 mM to 34.9+/-1.3 mM and 73. 9+/-1.9 mM at the end of ischemia and reperfusion, respectively. During single-dose cardioplegia the corresponding values for Na(i) were 30.2+/-1 mM and 48.5+/-1.7 mM (RPP=29%). Multiple infusions of cardioplegic solution resulted in a remarkable preservation of the heart's intracellular Na concentration with a non-significant increase in Na(i) during ischemia and only 16.7+/-1 mM, (P=0.01), after subsequent reperfusion (RPP=85%). The time course of Na(i) changes in the rat heart model demonstrates a prominent potential of multi-dose St Thomas' cardioplegia in preserving intracellular sodium homeostasis at 37 degrees C. The growth of Na(i) concentration during ischemia, as an indicator of the viability of the myocytes, can have a prognostic value for the heart's performance during reperfusion.

Modified open-door laminoplasty for treatment of neurological deficits in younger patients with congenital spinal stenosis: analysis of clinical and radiographic data.

OBJECT: Multilevel anterior cervical decompressive surgery and fusion effectively treats cervical myeloradiculopathy that is caused by severe cervical spinal stenosis, but degenerative changes at adjacent vertebral levels frequently result in long-term morbidity. The authors performed a modified open-door laminoplasty procedure in which allograft bone and titanium miniplates were used to treat cervical myeloradiculopathy in younger patients with congenital canal stenosis while maintaining functional cervical motion segments. Pre- and postoperative magnetic resonance imaging and/or computerized tomography myelography were performed to assess changes in cervical spinal canal dimensions. Pre- and postoperative flexion-extension radiographs were compared to determine the residual motion of the targeted operative segments. METHODS: Twenty younger patients (average age 37.7 years) underwent modified open-door laminoplasty for treatment of myelopathy or myeloradiculopathy related to significant cervical spinal stenosis with or without associated central or lateral disc herniation or foraminal stenosis. These surgeries were performed during a 2-year period and follow-up review remains ongoing (average follow-up period 21.6 months). Reconstructive procedures were performed on an average of 4.1 levels (range three-six). Operative time averaged 186 minutes (range 93-229 minutes). Average blood loss was 305 ml (range 100-650 ml). No cases were complicated by neurological deterioration, infection, wound breakdown, graft displacement, or hardware failure. The patients' Nurick Scale grade improved from a preoperative average of 1.8 to a postoperative average of 0.5. Pre- and postoperative sagittal spinal diameter averaged 11.2 mm (8-14 mm) and 16.6 mm (13-19 mm), respectively. The sagittal compression ratio (sagittal/lateral x 100%) increased from 48% pre- to 72% postoperatively. The spinal canal area increased an average of 55% (range 19-127%). In patients in whom pre- and postoperative flexion-extension radiographs were obtained, 72.7% residual neck motion was maintained. No patient developed increased neck or shoulder pain. Neurological symptoms improved in all patients, with total relief of myelopathy in 50% and partial improvement in 50%. CONCLUSIONS: Modified open-door laminoplasty with allograft bone and titanium miniplates effectively treats neurological deficits in younger patients with congenital and spinal stenosis. Although long-term results are unknown, short-term results are good and there is a low incidence of complications.

Sodium TQF NMR and intracellular sodium in isolated crystalloid perfused rat heart.

The feasibility of monitoring intracellular sodium changes using Na triple quantum filtered NMR without a chemical shift reagent (SR) was investigated in an isolated rat heart during a variety of interventions for Na(i) loading. Perfusion with 1 mM ouabain or without K+ present in the perfusate for 30 min produced a rise of the Na TQF signal with a plateau of approximately 190% and approximately 228% relative to the preintervention level, respectively. Stop-flow ischemia for 30 min resulted in a TQF signal growth of approximately 147%. The maximal Na TQF signal increase of 460% was achieved by perfusion without K+/Ca2+, corresponding to an elimination of the Na transmembrane gradient. The observed values of Na NMR TQF growth in the physiological and pathological ranges are in agreement with reported data by other methods and have a linear correlation with intracellular sodium content as determined in this study by Co-EDTA method and by sucrose-histidine washout of the extracellular space. Our data indicate that the increase in Na TQF NMR signal is determined by the growth of Na(i), and the extracellular Na contribution to the total TQF signal is unchanged at approximately 64%. In conclusion, Na TQF NMR without using SR offers a unique and noninvasive opportunity to monitor alterations of intracellular sodium. It may provide valuable insights for developing cardioprotective strategies and for observing the effects of pharmaceutical treatments on sodium homeostasis.

The influence of secondary gain on surgical outcome: a comparison between cervical and lumbar discectomy.

Although the expectation of monetary compensation has been associated with failures in lumbar discectomy, the issue has not been investigated in patients undergoing cervical disc surgery. The authors analyzed the relationship between economic forms of secondary gain and surgical outcome in a group of patients with a common pay scale, retirement plan, and disability program. All procedures were performed at the Portsmouth Naval Medical Center between 1993 and 1995; active-duty military servicepersons treated for cervical radiculopathy were prospectively included. Clinical, demographic, and financial factors were analyzed to determine which were predictive of outcome. Financial data were used to create a compensation incentive, which is proportional to the patient's rank, years of service, potential disability, retirement eligibility, and base pay and reflects the monetary incentive of disability. The results of cervical surgery were compared to a previously reported companion population of patients treated for lumbar disc disease. A good outcome was defined as a return to active duty, whereas a referral for disability was considered a poor surgical result. A 100% follow-up rate was obtained for 269 patients who underwent 307 cervical operations. Only 16% (43 of 269) of patients who underwent cervical operation received disability, whereas 24.7% (86 of 348) of patients who underwent lumbar discectomy obtained a poor result (p = 0.0082). Although economic forms of secondary gain were not associated with a poor outcome in cervical disease, both the rank (p = 0.002) and duration (p = 0.03) of an individual's military career were significant factors (p = 0.02). Of the medical variables tested, multilevel surgery (p = 0.03) and revision operations at the same level (p = 0.03) were associated with referral for medical discharge. Secondary gain in the form of economic compensation influences outcome in lumbar but not cervical disc surgery patients; the increased rate of disability referral in patients who underwent lumbar discectomy may reflect an expectation of economic compensation. Social factors that are independent of the anticipation of economic compensation seem to influence the outcome in cervical disc surgery patients.

Lumbar disc surgery in a fixed compensation population: a model for influence of secondary gain on surgical outcome.

BACKGROUND: Reported outcomes in patients undergoing surgical procedures for lumbar disc herniation are poorer in patients eligible for workers' compensation or with pending litigation. In the civilian community, the amount of compensation for one's disability is variable and thus its influence on surgical outcome is difficult to quantify. In the military, all members are covered by a standardized workers' compensation system, and have generally standardized work requirements, a standard pay scale, and third party evaluation of disability based on the Veterans Affairs rating system. This made the military a good system in which to study the effect of potential compensation on surgical outcome. METHODS: The study population consisted of active duty military members who underwent sequential lumbar microdiscectomies over a 31-month period. Omitted were lumbar fusions, decompressive laminectomies, and far lateral discectomies. Clinical and demographic variables, along with financial data for each patient were derived from these data. A good result was defined as return to active military duty. RESULTS: Three hundred forty-nine lumbar discectomies were performed in 348 active duty military members. Overall, 75.3% (262) of the 348 patients were able to return to full military duty after surgery, and 24.7% (86) received disability compensation. Chi-square univariate analysis showed higher compensation incentive was a significant determinant of poor surgical outcome (p = 0.0021). The influence of compensation incentive was proportional to the amount of anticipated payout, and relative to a military service member's usual income. In mutivariate analysis, lower base pay (0.0005) and female gender (p = 0.038) were predictive of poor outcome. CONCLUSIONS: Secondary gain in the form of disability pay has a proportionally adverse effect on outcome following lumbar disc surgery. Although studying this issue in the military system allowed standardization of secondary gain values, the influence of other factors could not be eliminated entirely. Potential disability pay is proportionally greater in lower ranked service members. Thus, other variables such as income level, education, and job satisfaction may contribute to the poorer results in this subgroup of military members.

Effects of specific sodium/hydrogen exchange inhibitor during cardioplegic arrest.

BACKGROUND: The accumulation of intracellular sodium during myocardial ischemia couples an inappropriate calcium influx and depressed cardiac recovery during subsequent reperfusion. The effects of the selective sodium/ hydrogen exchange inhibitor HOE 694 are evaluated during myocardial ischemia and reperfusion. METHODS: Ten isolated rat hearts were subjected to a 2-minute infusion of St. Thomas' cardioplegia +/- 1 mumol/L HOE 694 followed by 50 minutes' normothermic (37 degrees C) global ischemia. Intracellular sodium accumulation was continuously measured using triple quantum filtered 23Na nuclear magnetic resonance spectroscopy without chemical shift reagents. Hemodynamic variables were assessed before and after ischemia. RESULTS: The addition of 1 mumol/L HOE 694 to St. Thomas cardioplegic solution (n = 5) attenuated the accumulation of intracellular sodium after 50 minutes' ischemia (160.5% +/- 9.1% versus 203.4% +/- 10.9% [mean +/- standard error], HOE 694 versus control, respectively; p = 0.014) and after the initial reperfusion period (first 30 minutes) (288.7% +/- 10.2% versus 335.9% +/- 10.3%; p = 0.008). HOE 694-treated hearts showed significantly improved postischemic recovery of left ventricular developed pressure (53.5% +/- 8.4% versus 26.4% +/- 6.6%; p = 0.036) and rate-pressure product (40.2% +/- 6.9% versus 13.2% +/- 5%; p = 0.014). Postischemic recovery of coronary flow was not significantly different between the two groups (68.6% +/- 5.9% versus 55.5% +/- 4.6%, HOE 694 versus control, respectively; p = 0.11). CONCLUSIONS: The addition of 1 mumol/L HOE 694 to cardioplegic solution attenuates the increase of intracellular sodium during myocardial ischemia and early reperfusion. This is coupled with an improved recovery of contractile function, possibly as a result of decreased sodium and calcium overload of ischemic myocardium.

Two-portal endoscopic carpal tunnel release surgery: report of early experience.

Endoscopic carpal tunnel release is increasingly performed to treat median nerve entrapment neuropathy at the transverse carpal ligament. Proponents of these procedures claim that there are early postoperative advantages to be gained by the patient in the form of decreased pain and weakness, thus facilitating an earlier return to function. However, serious complications associated with the use of these techniques have been reported, especially during the surgeon's purported initial steep learning curve. A prospective analysis of the authors' first 51 cases using a two-portal endoscopic technique was conducted to determine whether these learning curve complications occurred. The authors did experience a learning curve; however, it was not significant. They encountered no serious complications and patient satisfaction was very high. It is concluded that the procedure is relatively easy to learn and safe to perform.

Preperitoneal suprahepatic pacemaker generator placement in the pediatric population.

We have used a preperitoneal suprahepatic location for pacemaker generator placement in pediatric patients requiring permanent pacemakers with epicardial leads. The technique is rapid, simple, and safe, and cosmesis is excellent, making this approach particularly advantageous in the younger infant and neonate.

Antegrade cold blood cardioplegia is not demonstrably advantageous over cold crystalloid cardioplegia in surgery for congenital heart disease.

OBJECTIVE: The superiority of blood cardioplegia in pediatric cardiac surgery has not previously been challenged in a controlled clinical trial. The purpose of this study was to compare antegrade cold blood versus cold crystalloid cardioplegia in pediatric cardiac surgery. METHODS: One hundred thirty-eight pediatric patients (mean age 32 months; 95% CL 24.2 to 39.8 months; range 1 day to 15 years) were prospectively randomized to receive either cold blood (4:1 dilution, blood/Plegisol, potassium chloride 15 mEq/L; n = 62) or cold crystalloid (Plegisol; n = 76) cardioplegic solution during a variety of operations for congenital heart disease. Multiple doses of cold (4 degrees C) cardioplegic solution was administered antegradely in addition to topical cooling during ischemic arrest. Myocardial recovery and outcome measures were assessed by five clinical end points: (1) inotropic support, (2) echocardiographic assessment of ventricular function, (3) overall complication rate, (4) length of stay in the intensive care unit, and (5) 30-day survival. Multiple logistic regression and multivariate analysis of variance were used to investigate which of the following clinical determinants were contributory: (1) cardioplegia, (2) urgency of operation, (3) aortic crossclamp time, (4) age, and (5) cyanosis. Population data did not differ between the two cardioplegia groups (p > 0.05). RESULTS: The most important clinical determinant of studied end points was the aortic crossclamp time (p < 0.05). The type of cardioplegic solution (blood vs crystalloid) was less important (p > 0.05). The only statistically significant difference between blood and crystalloid cardioplegia for the measured clinical end points was the level of intraoperative inotropic support (p < 0.05), although this did not correlate with any significant differences in measured ventricular function. CONCLUSION: Our results suggest no clear clinical advantage of antegrade cold blood cardioplegia over crystalloid cardioplegia during hypothermic cardioplegic arrest in pediatric cardiac surgery. The aortic crossclamp time was the strongest predictor of measured outcomes.

Pericardial substitute and emergency resternotomy: life-saving combination.

Retrosternal adhesions prolong operating time during reoperative pediatric cardiac surgery and promote myocardial injury. A case is presented in which a polytetrafluoroethylene pericardial substitute facilitated a rapid, life-saving emergency resternotomy in a moribund patient.

Modified surgical palliation for a rare type of L-transposition with aortic atresia.

L-Transposition of the great arteries with aortic atresia without an outlet chamber is a rare congenital heart defect. We used a modified Norwood procedure incorporating a type of direct coronary transfer for successful palliation of this lesion in a neonate.

Simultaneous manipulation of the nitric oxide and prostanoid pathways reduces myocardial reperfusion injury.

The effects of aspirin and L-arginine (biological precursor of nitric oxide) on the production of hydroxyl radicals, cyclic guanosine monophosphate levels, vascular tone, and the recovery of the ischemic myocardium were investigated in isolated rat hearts subjected to ischemia and reperfusion. After 30 minutes of perfusion, hearts were arrested with St. Thomas' Hospital cardioplegic solution, global ischemia was induced at 37 degrees C for 45 minutes, and the hearts were then reperfused at 37 degrees C for 30 minutes. The percent change in recovery of pulse pressure and maximal change of this pressure with time were better in the group perfused with Krebs-Henseleit solution containing aspirin plus L-arginine (17% +/- 23%, p = 0.001, and 10% +/- 25%, p = 0.002, respectively) compared with these values in the control group perfused with Krebs-Henseleit solution alone (-7% +/- 14% and -11% +/- 16%, respectively). Coronary vascular resistance before and after ischemia were lower in the aspirin plus L-arginine group (0.19 +/- 0.03 dynes.sec/cm5, p = 0.001, and 0.23 +/- 0.04 dynes.sec/cm5, p = 0.01, respectively) compared with those of the control group (0.24 +/- 0.02 and 0.28 +/- 0.07 dynes.sec/cm5, respectively). Cyclic guanosine monophosphate levels increased from 22.5 +/- 6 pmol/100 mg of tissue in the control group to 37.1 +/- 8.9 pmol/100 mg (p = 0.002) in the aspirin plus L-arginine group. Adding N omega-nitro-L-arginine methyl ester to the perfusion medium caused a deterioration in pulse pressure and maximal change of this pressure with time, a decrease in cyclic guanosine monophosphate, and a rise in coronary vascular resistance. The addition of L-arginine to the solution in the Krebs-Henseleit solution plus aspirin group increased the production of hydroxyl radicals from 0.32 +/- 0.18 nmol/gm per 3 minutes to 0.75 +/- 0.33 nmol/gm per 3 minutes (p = 0.03). Despite the association of nitric oxide with increased hydroxyl radical production, it appears that nitric oxide has an overall beneficial effect on the recovery of the ischemic myocardium. The synergism between aspirin and arginine may be caused in part by the scavenging of hydroxyl radicals. Alternatively, by inhibiting the prostaglandin pathway, aspirin may reduce the generation of superoxide anion, a free radical that inactivates nitric oxide. The prolonged half-life of nitric oxide may explain the increased levels of cyclic guanosine monophosphate seen in the group perfused with Krebs-Henseleit solution plus aspirin plus L-arginine. Aspirin and L-arginine, both readily available, may be useful adjuncts to clinical cardioplegia strategy.

Left thoracotomy for emergent repair of ventricular rupture during mitral valve replacement.

Ventricular rupture is a dreaded complication of mitral valve replacement. We present a case of ventricular rupture that occurred during mitral valve replacement and was successfully repaired through a left thoracotomy approach.

Balloon occlusion scintigraphy of aortopulmonary collaterals.

We evaluated two children with pulmonary atresia for coil embolization of aortopulmonary collateral vessels after placement of palliative aortopulmonary shunts. To determine vessel distribution and lung perfusion prior to collateral embolization, perfusion scintigraphy with technetium 99m-labeled macroaggregated albumin assessed pulmonary blood flow before and after balloon wedge catheter occlusion of the collaterals. In the first patient we found no perfusion defect during collateral occlusion, and we proceeded with embolization. In the second child, perfusion scintigraphy during occlusion of the collateral vessels demonstrated a filling defect, and embolization was not performed, thus avoiding the creation of a potential perfusion defect in this patient. Assessing the physiologic significance of aortopulmonary collateral vessels by utilizing temporary balloon occlusion of the collateral vessels and concurrent perfusion scintigraphy as an adjunct to selective angiography can provide a significant contribution to the safety and accuracy of coil embolization.

Partial sensory trigeminal rhizotomy at the pons for trigeminal neuralgia.

Microvascular decompression is preferred among open procedures for the treatment of trigeminal neuralgia. However, in some cases the decompression cannot be performed, either because no significant vascular compression of the trigeminal nerve is found at surgery or because a patient's vascular anatomy makes it unsafe. Partial sensory rhizotomy is a commonly used alternative in these instances. The outcome after partial sensory rhizotomy was reviewed retrospectively in 83 patients with an average follow-up period of 72 months. Sixty-four (77%) of these patients had no evidence of vascular contact at operation. The remaining 19 patients (23%) had vascular structures in proximity to the trigeminal nerve but still underwent partial sensory rhizotomy in place of or in addition to microvascular decompression either because the offending vessel could not be moved adequately (11 cases) or because the vascular contact was considered insignificant (eight cases). Outcome was classified as: excellent if there was no trigeminal neuralgia postoperatively; good if pain persisted or recurred but was less severe than preoperatively; and poor if persistent or recurrent pain was equal to or greater than the preoperative pain in severity and was refractory to medication, or was severe enough to require additional surgery. The outcome was excellent in 40 patients (48%), good in 18 (22%), and poor in 25 (30%); follow-up durations were similar for the three outcome categories. The failure rate was 17% for the 1st year and averaged 2.6% each year thereafter. Two variables were predictive of a poor outcome: prior surgery and lack of preoperative involvement of the third trigeminal division. Major complications occurred in 4% of cases and minor complications in 11%. The authors conclude that partial sensory rhizotomy is a safe and effective alternative to microvascular decompression when neurovascular compression is not identified at operation or when microvascular decompression cannot be performed for technical reasons.