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PubMed1994

Intraoperative facial nerve monitoring: a description of a unique system.

Intraoperative facial nerve monitoring has become an integral adjunct in facial nerve identification and preservation for patients undergoing cerebellopontine angle surgery. Since the first description of EMG monitoring of facial nerve activity intraoperatively, many systems have been developed. These systems often rely on unilateral monitoring of the facial nerve with auditory feedback to the surgeon, and it is difficult to distinguish between artifact and significant stimulation of the facial nerve. In this paper, we present the use of a bilateral, multialarm, facial nerve monitoring system that has multiple advantages over previous systems. Furthermore, we review our experience with this bilateral system, comparing a group of 50 monitored patients to a group of 50 unmonitored patients.

Adolescent↗

PubMed1995

A new method of multisegment motor pathway monitoring using muscle potentials after train spinal stimulation.

STUDY DESIGN: Evoked muscle and nerve action potentials after spinal stimulation for intraoperative monitoring were investigated using a modified stimulation technique. Animal experiments and clinical application were performed. OBJECTIVES: To contrive a useful method of intraoperative motor pathway monitoring under inhalation anesthesia. SUMMARY OF BACKGROUND DATA: Many different kinds of procedures have been reported. No reliable method that reflects pure motor tract function has been established. METHODS: Characteristic of our stimulating technique was the use of numbered consecutive pulses ("train stimulation"). In 16 cats, optimum condition of train stimulation, effects of anesthetic agents, and conductive pathway were examined. In 35 patients, muscle potentials evoked by train stimulation were recorded, and clinical usefulness was evaluated. RESULTS: In the experimental study, the optimum stimulus condition was determined 1 ms interstimulous interval train of five pulses. Conductive pathway of this method was identified as a lateral column by selective spinal cord transection. In the clinical application, by using train stimulation, multisegmental muscle potentials were obtainable even using inhalation anesthetics. CONCLUSIONS: The facilitative effects of train stimulation, attributed to temporal summation, are considered to overcome the suppression of inhalation anesthesia. The evoked muscle potentials by train spinal stimulation reflect the functions of pure motor tract and is the only, extremely efficient method for intraoperative motor pathway monitoring.

Action Potentials↗

PubMed2006

[Anesthetic management of corpus callosotomy with electrophysiological monitoring: a case report].

We report anesthetic management of a 5-year-old girl for corpus callosotomy indicated for the treatment of intractable epilepsy. The procedure mandated intraoperative monitoring of evoked potentials and electrocorticogram. During the first half of the surgery until the corpus callosum was exposed, anesthesia was maintained with continuous infusion of propofol. Motor and somatosensory evoked potentials were monitored and diagnosed as intact throughout the procedure, with no epileptic activity observed in 32-lead electrocorticogram. Then propofol infusion was replaced with the inhalation of sevoflurane, 2.0% in air/oxygen mixture, which induced epileptic spike-and-wave activities, synchronized between the hemispheres, in electrocorticogram. After the completion of corpus callosotomy, we observed interhemispheric desynchronization of epileptic activities indicating successful surgical intervention. The patient emerged from anesthesia uneventfully with no neurological deficits, and thereafter with decreased incidence of generalized epileptic episodes. We suggest that such switch of anesthetic agents between propofol and sevoflurane should be helpful in intraoperative electrophysiological monitoring for ascertaining both functional preservation and successful intervention during epileptic surgery.

Anesthesia↗

PubMed2002

[Intraoperative computer tomography control within the scope of maxillofacial traumatology using a mobile scanner].

Advances in intra-operative imaging and the development of new minimally invasive techniques are having an ever greater impact on modern surgery. Mobile CT scanners in the operating room is a new technique that permits image-guided surgery, and helps minimize postoperative complications. We report on our initial experience with intraoperative CT scanning during surgery on patients suffering lateral midface trauma. A mobile CT unit, the Tomoscan M (Philips, Utrecht, Netherlands) set up in the operating room, was evaluated in 6 patients with zygomatic bone fractures. The patients were placed on the CT scanner table, which is detachable from the gantry. The unit is powered by batteries charged from an ordinary ring mains supply via a conventional plug. The CT images obtained were of good quality in all cases. No technical problems were observed during surgery. Using repeat CT scans, the procedure also permits accurate intraoperative monitoring of the anatomical repositioning of the bone fragments, and accurate implantation. No intraoperative or early postoperative complications were observed. This new technical aid ensures highly accurate reduction of the bone fragments, and minimizes the need for reoperation. High-quality intraoperative imaging with surgical navigation increase surgical outcome, and expand the spectrum of minimally invasive surgery.

Fracture Fixation, Internal↗

PubMed2000

Intracerebral steal phenomenon associated with global hyperemia in moyamoya disease during revascularization surgery.

OBJECT: The collateral vessels in moyamoya disease appear to retain their ability to constrict during hypocapnia but not to dilate during hypercapnia. It has been claimed that hypercapnia, as well as hypocapnia, decreases the blood flow in regions perfused by collateral vessels, presumably because of intracerebral steal. If this holds true, the decrease in blood flow may be proportional to the global hyperemia in the brain. To establish appropriate hemodynamic control during revascularization surgery, the authors monitored the jugular bulb oxygen saturation (SjO2) intraoperatively, a method that could sensitively detect global hyperemia. METHODS: A total of 17 patients, most of whom presented with transient ischemic attacks or fluctuating neurological deficits, underwent intraoperative monitoring of their SjO2 and end-tidal carbon dioxide (ETCO2) after a state of anesthesia had been induced with isoflurane (Group 1) or propofol (Group 2). In eight of these patients, the regional cerebral blood flow (rCBF) of the collateral vessel territory was also monitored by laser Doppler flowmetry during the period of cortical exposure, and a total of 113 data sets (averaged values during 2.5-minute intervals) was collected. There was fluctuation in the ETCO2 levels ranging from 36 to 44 mm Hg. The mean SjO2 level was clearly greater (p < 0.01) in Group 1 (71.8 +/- 2.2%) than in Group 2 (63.3 +/- 2.1%). An episodic fall in rCBF was observed in association with a transient increase in SjO2. Such an event was not uncommon in Group 1 and there was a greater risk of rCBF decreasing when SjO2 exceeded a cutoff level of 76% (p < 0.01). This level could sometimes be reached at a broad range of ETCO2 readings (37-44 mm Hg). In Group 2, similar events sometimes occurred when SjO2 increased beyond 70%. However, this level could be reached only with a higher ETCO2 (42-44 mm Hg). The rCBF level was negatively correlated to SjO2 (p < 0.01), but not always to ETCO2, indicating that the episodic fall in rCBF was closely related to global hyperemia rather than the absolute level of hypercapnia. CONCLUSIONS: The observed association between a fall in rCBF and global hyperemia supports the intracerebral steal hypothesis and indicates that it is prudent to avoid excessive global hyperemia. The optimal range of CO2 for isoflurane is more restricted than that for propofol, presumably because isoflurane induces hyperemia by itself. Monitoring of SjO2 appears to represent the most practical technique for detecting global hyperemia as well as global ischemia, both of which may cause ischemic complications in moyamoya disease.

Adolescent↗

PubMed1993

Quality assurance for intraoperative transesophageal echocardiography monitoring: a report of 846 procedures.

We evaluated our experience with 846 consecutive transesophageal echocardiography (TEE) intraoperative monitoring procedures performed between November 1989 and July 1991. TEE frequency was 36 +/- 11 per month (range 16-55) and represented 69.8% of cardiac valve surgery cases, 40.2% of coronary artery bypass graft cases, and 2.2% of total operative caseload. Major patient complications consisted of transient vocal cord paresis and ingestion of glutaraldehyde-disinfectant solution. Minor complications consisted of a chipped tooth (one case) and pharyngeal abrasions (three cases). The Quality Assurance (Q/A) Program evaluated both record keeping and quality of imaging, as judged by cardiologist echocardiographer reviewers. The percentage of completion for each Q/A indicator was as follows: medical record documentation, 88%; database form annotation, 94%; and provision of videotape recording, 91%. TEE database forms were analyzed further in terms of the percentage of fields completed. Completion scores were 73%. The following scoring system was utilized for videotape evaluation by the cardiologists: 1 = excellent; 2 = good; 3 = poor. The median grade for both two-dimensional echocardiography and color flow Doppler (CFD) examinations was 2. Poor quality images (grade 3) were present in 15.2% of two-dimensional echocardiography and 20.3% of color flow Doppler examinations, and disproportionately associated with 4/26 attendings. Supplemental audit of the cardiology reviewers performance demonstrated 569/846 videotapes showed no objective evidence of review. The cardiology reviewer forms of the remaining 277 videotapes were evaluated in terms of the percentage of fields completed. The completion score was 56%. These data suggest the need for formal Q/A for intraoperative TEE, both for anesthesiologists and reviewing cardiologists.

Echocardiography↗

PubMed1994

Intraoperative facial nerve monitoring in the surgery of cerebellopontine angle tumors: improved preservation of nerve function.

The surgery of cerebellopontine angle tumors has shown remarkable progress over the last 20 years due to improved microsurgical techniques. However, the dissection of the facial nerve may lead to postoperative paresis as the result of the surgical trauma and the disruption of blood supply over a large distance. The functional status of the nerve can be intraoperatively monitored by means of intramuscular electromyography of facial muscles and direct electrical stimulation. In this study, the impact of monitoring techniques on the preservation of facial function was evaluated by comparing monitored (n = 30) and unmonitored (n = 34) patients. Both groups were comparable with regard to the size of the tumor, the surgical approach and the duration of operation. All patients were operated by the same surgeon (T.L.) either via the middle fossa or the translabyrinthine approach. The EMG was recorded with needle electrodes from the orbicularis oris and oculi muscles. For electrical stimulation, bipolar forcep electrodes were used delivering rectangular, constant current pulses of 100 microseconds duration and a current strength between 0.05 and 0.8 mA. The mechanically or thermally elicited activity by drilling, direct manipulation or coagulation consisted of bursts and trains which are signs of minor nerve impairment. Their occurrence can lead to a modified surgical technique with a more precise preparation around and at the facial nerve. The immediate postoperative nerve function was normal or showed only a minor impairment (classes I and II according to House and Brackmann) in 87% of the monitored as compared with 74% of the unmonitored patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Cerebellopontine Angle↗

PubMed1999

Optimal stimulus duration for intraoperative facial nerve monitoring.

OBJECTIVES/HYPOTHESIS: The charge delivered to the facial nerve during intraoperative facial nerve monitoring (IOFNM) is the product of the stimulation amplitude and the duration for which the pulse of charge is applied. In the literature, no standard for pulse duration exists, precluding meaningful comparison of IOFNM between studies. The optimal stimulus pulse duration can be derived from facial nerve strength duration curve analysis and calculation of chronaxy. Chronaxy is directly related to the time constant, tau, of the neuronal membrane, and is a function of neuronal membrane resistance and capacitance. STUDY DESIGN: A prospective trial of facial nerve stimulation in both an animal and a human model. METHODS: Five rabbits and 17 humans underwent intraoperative stimulation of healthy facial nerves. Pulse durations using pulses of 10, 20, 50, and 100 microseconds were employed, and the corresponding threshold stimulation amplitudes were recorded. From these data sets, strength duration curves were plotted and chronaxy values calculated. RESULTS: Average chronaxy values of 18 microseconds in the rabbit and 32 microseconds in the human were found. Given IOFNM system accuracy limitations, the optimal pulse duration for facial nerve stimulation is 50 microseconds. CONCLUSION: Most commercially available intraoperative monitoring systems employ a pulse duration default setting of 100 microseconds. Doubling of the 50-microsecond optimal pulse duration may result in a loss of sensitivity of predictive facial nerve data. Both the stimulation amplitude and the selected pulse duration should be reported by investigators so that meaningful comparison of the IOFNM data in the literature can be made.

Animals↗

PubMed2006

Electrical impedance tomography: changes in distribution of pulmonary ventilation during laparoscopic surgery in a porcine model.

BACKGROUND: Because of the creation of a pneumoperitoneum, impairment of ventilation is a common side-effect during laparoscopic surgery. Electrical impedance tomography (EIT) is a method with the potential for becoming a tool to quantify these alterations during surgery. We have studied the change of regional ventilation during and after laparoscopic surgery with EIT and compared the diagnostic findings with computed tomography (CT) scans in a porcine study. MATERIALS AND METHODS: After approval by the local animal ethics committee, six pigs were included in the study. Two laparoscopic operations were performed [colon resection (n=3) and fundoplicatio (n=3)]. The EIT measurements (6th parasternal intercostal space) were continuously recorded by an EIT prototype (EIT Evaluation Kit, Dräger Medical, Lübeck, Germany). To verify ventilatory alterations detected by EIT, a CT scan was performed postoperatively. RESULTS: Ventilation with defined tidal volumes was significantly correlated to EIT measurements (r2=0.99). After creation of the pneumoperitoneum, lung compliance typically decreased, which agreed well with an alteration of the distribution of pulmonary ventilation measured by EIT. Elevation of positive end-inspiratory pressure reopened non-aerated lung areas and showed a recovery of the regional ventilation measured by EIT. Additionally, we could detect pulmonary complications by EIT monitoring as verified by CT scans postoperatively. CONCLUSION: EIT monitoring can be used as a continuous non-invasive intraoperative monitor of ventilation to detect regional changes of ventilation and pulmonary complications during laparoscopic surgery. These EIT findings indicate that surgeons and anesthetists may eventually be able to optimize ventilation directly in the operating theatre.

Animals↗

PubMedDate not supplied

Predictors and outcomes of cardiac complications following elective coronary bypass grafting.

Our objective was to determine the predictors of cardiac complications among a cohort of elective coronary artery bypass graft (CABG) surgery patients and to determine the relationship of such complications to subsequent quality of life and symptoms. A total of 248 patients were enrolled and 237 completed 6 month follow-up. The combined rate of both major and minor cardiac complications was 9.7% (n = 24). Patients in this study were evaluated preoperatively, monitored intraoperatively, followed immediately postoperatively and at 6 months. Major cardiac complications accounted for 3.6% (n = 9) and minor complications for 6% (n = 15). Using multivariable logistic regression analysis, the predictors of major cardiac complications were receiving diuretics preoperatively (p = .01) and increased time during cross-clamping (p = .006). At 6 months after surgery, 19% of the patients with postoperative cardiac complications experienced worsening of symptoms, in contrast to only 8% of those without cardiac complications (p = .03). We concluded that patients who were on preoperative diuretics and those who had longer cross-clamp times were at higher risk of cardiac complications. The majority of patients who had acute cardiac complications had improved function and symptoms at 6 months postoperatively.

Aged↗

PubMed2005

Unexpected results using rapid intraoperative parathyroid hormone monitoring during parathyroidectomy for primary hyperparathyroidism.

Rapid intraoperative parathyroid hormone (RIOPTH) monitoring predicts complete removal of all hypersecreting tissue by means of a significant parathyroid hormone (PTH) decrease. In this study we have tried to provide an explanation for some unexpected results of RIOPTH monitoring observed during a series of 125 conventional parathyroidectomies for primary hyperthyroidism, discussing the possible consequences on the surgical strategy. Three main groups can be recognized: (1) spikes: a PTH increase 10 minutes after removal of the diseased gland was observed in three patients; (2) false-negative results: six patients showed an inadequate PTH decreases at 10 minutes, three of them resulting in cure at 20 minutes (all six patients were cured at follow-up); (3) false-positive results: five patients with multiglandular disease showed a PTH decrease to a cure level despite excision of one adenoma only (in two of these patients a 20-minute sample showed a PTH increase soon after manipulation of the second adenoma). We concluded that the spike, almost certainly a consequence of manipulating the adenoma, when detected should be considered the "true" baseline value. False-negative results are to some extent related to undetected spikes. The assay used for RIOPTH determination and PTH half-life variability may also play a role. A false-negative result usually prolongs the surgical time. False-positive results are usually related to a double adenoma, one functionally prevailing over the other. Because in our experience manipulation of the second adenoma brought a PTH increase detected with RIOPTH monitoring, we believe that the second adenoma should be excised.

Aged↗

PubMed2002

Neurophysiologic monitoring of spinal nerve root function during instrumented posterior lumbar spine surgery.

STUDY DESIGN: Retrospective review of 61 consecutive patients. OBJECTIVES: To determine the effectiveness of combining intraoperative monitoring of both spontaneous electromyographic activity and compound muscle action potential response to stimulation for detecting a perforation of the pedicle cortex irritation of nerve root during lumbar spine fusion surgery. SUMMARY OF BACKGROUND DATA: The complication rate from instrumentation used with lumbar spine fusion varies from 1 to 33%. To prevent neurologic complications, several monitoring techniques have been used to alert surgeons to possible neurologic damage being introduced during nerve decompression or placement of instrumentation with spine procedures. Because of different sensitivities, one monitoring technique may not be as effective for preventing complications as a combination of techniques. METHODS: Sixty-one consecutive patients who underwent instrumented posterior lumbar fusions received continuous electromyographic monitoring and stimulus-evoked electromyographic monitoring. A significant neurophysiologic event was signaled by sustained neurotonic electromyographic activity, prompting an alert and a pause in the surgical manipulations that precipitated the activity. After insertion of the transpedicular screws, the integrity of the pedicle cortex was tested by stimulating each screw head and recording compound muscle action potentials. In the presence of a pedicle breach, stimulus intensities below 7 mA were sufficient to evoke compound muscle action potentials from the muscle group innervated by the adjacent spinal nerve root, prompting a surgical alert and subsequent repositioning of the screw. RESULTS: Fourteen significant neurophysiologic events occurred in 13 of 61 patients (21%). Sustained neurotonic electromyographic discharges occurred in 5 of 40 patients during placement of interbody fusion cages, in 2 patients during placement of transpedicular screws, and in 1 patient during tightening of rods. On pedicle screw stimulation, breaches of the pedicle cortex were detected in 6 patients. After surgery, no new neurologic deficits were found in 60 of the 61 patients. One patient who experienced temporary paraparesis had sustained neurotonic electromyographic discharges during retraction of the thecal sac and distraction of the disc space before placement of the cage. CONCLUSION: These results suggest that intraoperative electromyographic monitoring provides a real-time measure of impending spinal nerve root injury during instrumented posterior lumbar fusion, allowing for timely intervention and minimization of negative postoperative sequela.

Action Potentials↗

PubMed1999

Automatic detection of intraoperative neurological injury.

Neurological injuries occurring during high-risk surgical procedures can be detected by monitoring intraoperative evoked potential signals. In this communication, an automatic injury detection algorithm is proposed in which the EP signal is modeled as a pole-zero filter and then the model parameters are applied as inputs to a classifier type neural network. A recognition rate of 96% is achieved using an experimental model of brain injury.

Algorithms↗

PubMed2004

Application of Bispectral Index and Narcotrend index to the measurement of the electroencephalographic effects of isoflurane with and without burst suppression.

BACKGROUND: The Narcotrend monitor (MonitorTechnik, Bad Bramstedt, Germany) has recently been introduced as an intraoperative monitor of anesthetic state, based on a classification scheme originally developed for visual assessment of the electroencephalogram. The authors compared the performance of the Narcotrend index (software version 4.0) to the Bispectral Index (BIS, version XP; Aspect Medical Systems, Natick, MA) as electroencephalographic measures of isoflurane drug effect during general anesthesia. METHODS: The authors observed 15 adult patients scheduled to undergo radical prostatectomy with a combined epidural-isoflurane general anesthesia technique. At least 45 min after induction of general anesthesia, during a phase of constant surgical stimulation, end-tidal isoflurane concentrations were varied between 0.5 and 2.0 multiples of minimum alveolar concentration, and the BIS and the Narcotrend index were recorded. The prediction probability (PK) was calculated for the BIS and the Narcotrend index to predict isoflurane effect compartment concentration for each measure. The correlation analysis of the BIS and the Narcotrend index with the isoflurane effect compartment concentration was obtained by pharmacodynamic modeling based on two sigmoidal curves to account for the discontinuity in both indices with the onset of burst suppression. RESULTS: The prediction probabilities were indistinguishable (BIS PK = 0.72 +/- 0.07 (mean +/- SD); range, 0.61-0.84; Narcotrend index PK = 0.72 +/- 0.10; range, 0.51-0.87), as were the correlations between the electroencephalographic measures and isoflurane effect compartment concentrations (BIS R = 0.82 +/- 0.12; Narcotrend index R = 0.85 +/- 0.09). The pharmacodynamic models for the BIS and the Narcotrend index yielded nearly identical results. CONCLUSIONS: The BIS and the Narcotrend index detected the electroencephalographic effects of isoflurane equally. Combining two fractional sigmoid Emax models adequately described the data before and after the onset of burst suppression.

Aged↗

PubMed1997

[Practical localization of the central sulcus using a video display during surgery by cortical somatosensory evoked potentials and how to discern precentral P20 and central P25].

In patients with lesions around the central sulcus, cortical surface somatosensory evoked potentials (SEPs) have been applied for the purpose of localization of the central sulcus based on the polarity inversion of postcentral N20 to precentral P20 across the central sulcus. We have intraoperatively monitored SEPs to infer the location of the central sulcus in 16 cases since December 1988. Intraoperative localization of the central sulcus has been most useful in patients with frontal lobe gliomas in which the localization of the central sulcus enables the surgeon to extensively resect tumor without postoperative motor weakness. The localization of the central sulcus, however, might be misjudged by using the polarity inversion criterion alone, because central P25 following N20 and P20 complicates SEP waveforms. It is significant that P25, which is recorded also posterior to the central sulcus, is discerned from the precentral P20. In order to solve this matter, we regarded only the positivity in SEP waveforms having the identical peak latency to that of N20 as the precentral P20. Positive potentials having a later peak latency than that of N20 are the superposition of P20 and P25, and might also be recorded posterior to the central sulcus. For the observation of the polarity inversion of N20 to P20 across the central sulcus, a multi-channel SEP should be recorded using a sheet of silicone rubber embedded in a 16-electrode array consisting of a 4 by 4 grid. We projected the exposed cortical surface on the video display through the microscope apparatus and marked the locations of the recording electrodes on the video display. This enabled the location of the recording electrodes to correspond easily and precisely to the cortical surface. Our reliable and simple method of intraoperative localization of the central sulcus by cortical SEPs monitoring is presented in a practical case.

Adolescent↗

PubMed1993

Issues in the optimal selection of a cranial nerve monitoring system.

Intraoperative nerve monitoring (IONM) is a safe technique that is of clear clinical value in the preservation of cranial nerves in skull base surgery and is rapidly becoming the standard of care. Available nerve monitoring systems vary widely in capabilities and costs. A well-informed surgeon may best decide on monitoring needs based on surgical case selection, experience, operating room space, availability of monitoring personnel, and cost. Key system characteristics that should be reviewed in the decision-making process include the monitoring technique (electromyography, pressure transducer, direct nerve monitoring, brainstem auditory evoked potential) and the stimulus technique (stimulating parameters, probe selection). In the past, IONM has been primarily employed in posterior fossa and temporal bone surgery, but the value of IONM is being recognized in more skull base and head and neck surgeries. Suggested IONM strategies for specific surgeries are presented.

Journal Article↗

PubMed2006

The effects of stimulation pattern and sevoflurane concentration on intraoperative motor-evoked potentials.

The usefulness of intraoperative monitoring of motor-evoked potentials (MEPs) during inhaled anesthesia is limited by the suppressive effects of volatile anesthetics on MEP signals. We investigated the effects of different stimulation patterns and end-tidal concentrations of sevoflurane on intraoperative transcranial electrical MEPs. In 12 patients undergoing craniotomy, stimulation patterns (300-500 V, 100-1000 Hz, 1-5 stimuli) and multiples (0.5, 0.75, and 1.0) of minimum alveolar concentration (MAC) of sevoflurane were varied randomly while remifentanil was administered at a constant rate of 0.2 microg x kg(-1) x min(-1). MEPs were recorded from thenar and hypothenar muscles and analyzed without knowledge of the respective MAC. Three-way analysis of variance revealed significant main effects for increasing stimulation intensity, frequency, and number of stimuli on MEP amplitude (P < 0.05). Maximum MEP amplitudes and recording success rates were observed during 4 stimuli delivered at 1000 Hz and 300 V. A significant main effect of sevoflurane concentration (0.5 versus 0.75 and 1 MAC multiple) on MEP amplitude was observed at the thenar recording site only (P < 0.05). In conclusion, MEP characteristics varied significantly with changes in stimulation pattern and less so with changes in sevoflurane concentration. The results suggest that high frequency repetitive stimulation allows intraoperative use of MEP monitoring during up to 1 MAC multiple of sevoflurane and constant infusion of remifentanil up to 0.2 microg x kg(-1) x min(-1).

Adult↗

PubMed2006

Consequences of targeted parathyroidectomy guided by localization studies without intraoperative parathyroid hormone monitoring.

BACKGROUND: After excision of an abnormal gland, the dynamics of intraoperative parathyroid hormone (PTH) levels signal whether or not more hypersecreting tissue is present. This quantitative assurance of operative success has led to targeted exploration of the hyperfunctioning gland(s). Some have questioned the need for intraoperative PTH monitoring (IPM) in the presence of positive nuclear scanning. The purpose of this study was to examine the accuracy of nuclear scans in correctly localizing and guiding the complete excision of all abnormal gland(s) in patients with sporadic primary hyperparathyroidism (SPHPT) and to demonstrate how IPM changed the operative management in these patients. STUDY DESIGN: Five hundred nineteen consecutive patients with sporadic primary hyperparathyroidism had technetium 99-m-sestamibi scans (MIBI) as localization studies obtained before undergoing parathyroidectomy guided exclusively by IPM. All patients were either followed for more than 6 months, or their procedures were identified as operative failures. MIBI reports were correlated with operative findings, hormone dynamics, and postoperative outcomes. RESULTS: Operative success was achieved in 506 of 519 patients (97%). MIBI correctly localized all involved glands in 411 patients (80%). Among the 105 patients (20%) with incorrect or negative scans, IPM changed the operative management in 86 of 105 (82%) by pointing out incomplete resection in patients with a single MIBI incorrect focus (21 of 28) or unrecognized multiglandular disease by scan (13 of 15); avoiding unnecessary exploration in patients with additional incorrect foci (20 of 21); and guiding the surgeon to successful excision or unilateral neck exploration in patients with negative MIBI (32 of 41). CONCLUSIONS: MIBI as a single adjunct missed 87% of patients with multiglandular disease. Including patients with negative (8%) and incorrect (12%) MIBI, IPM changed the operative management in 17% of patients and led to operative success in 97%. We suggest that IPM should be used to guide parathyroid excision in every patient with sporadic primary hyperparathyroidism.

Female↗