Total intravenous anesthesia for intraoperative monitoring of the motor pathways: an integral view combining clinical and experimental data

2002 ◽  
Vol 96 (3) ◽  
pp. 571-579 ◽  
Author(s):  
Kai-Michael Scheufler ◽  
Josef Zentner
Keyword(s):  
Motor Evoked Potentials ◽  
Plasma Concentrations ◽  
Total Intravenous Anesthesia ◽  
Neurological Deficits ◽  
Experimental Investigations ◽  
Intravenous Anesthesia ◽  
Content Type ◽  
Precise Knowledge ◽  
Dose Dependent ◽  
Fine Print

Object. Monitoring of descending corticospinal pathways by using motor evoked potentials (MEPs) has proven to be useful in preventing permanent neurological deficits during cranial and spinal procedures. Difficulties in interpretation of intraoperative changes in potentials may largely be attributed to the effects of anesthesia. Development of suitable intravenous anesthesia protocols specifically tailored for MEP monitoring, including plasma level target-controlled infusion (TCI), requires precise knowledge of the specific neurophysiological properties of the various agents. Methods. The effects of alfentanil, sufentanil, fentanyl, remifentanil, thiopental, midazolam, etomidate, ketamine, and propofol on neurogenic and myogenic MEPs were evaluated in an integral study combining clinical data obtained in 40 patients and experimental investigations conducted in 140 animals. The dose-dependent modulation of MEPs after electrical and magnetoelectrical stimulation of the motor cortex was recorded from peripheral muscles and the spinal cord. The results were as follows: opioids, propofol, and thiopental suppressed myogenic, but not neurogenic MEPs in a dose-dependent fashion; remifentanil exerted the least suppressive effects. Etomidate and midazolam did not suppress myogenic MEP, even at plasma concentrations sufficient for anesthesia. Ketamine induced moderate reduction of compound muscle action potential amplitudes only at high doses. Remifentanil and propofol administered via TCI systems allowed recording of myogenic potentials within a defined target plasma concentration range. Conclusions. Development of standardized total intravenous anesthesia/TCI protocols by using anesthetic agents such as propofol, remifentanil, ketamine, and midazolam, which have favorable pharmacokinetic and neurophysiological properties, will enhance the quality of intraoperative MEPs and promote the use of MEP monitoring as a useful tool to reduce surgery-related morbidity.

Plasma endothelin concentrations after aneurysmal subarachnoid hemorrhage

2000 ◽  
Vol 92 (3) ◽  
pp. 390-400 ◽  
Author(s):  
Seppo Juvela
Keyword(s):  
Subarachnoid Hemorrhage ◽  
Cerebral Ischemia ◽  
Healthy Volunteers ◽  
Aneurysmal Subarachnoid Hemorrhage ◽  
Plasma Concentrations ◽  
Delayed Cerebral Ischemia ◽  
Neurological Deficits ◽  
Content Type ◽  
History Of ◽  
Fine Print

Object. The pathogenesis of cerebral vasospasm and delayed ischemia after subarachnoid hemorrhage (SAH) seems to be complex. An important mediator of chronic vasospasm may be endothelin (ET), with its powerful and long-lasting vasoconstricting activity. In this study the author investigated the correlation between serial plasma concentrations of ET and ischemic symptoms, angiographically demonstrated evidence of vasospasm, and computerized tomography (CT) findings after aneurysmal SAH.Methods. Endothelin-1 immunoreactivity in plasma was studied in 70 patients with aneurysmal SAH and in 25 healthy volunteers by using a double-antibody sandwich-enzyme immunoassay (immunometric) technique.On the whole, mean plasma ET concentrations in patients with SAH (mean ± standard error of mean, 2.1 ± 0.1 pg/ml) did not differ from those of healthy volunteers (1.9 ± 0.2 pg/ml). Endothelin concentrations were significantly higher (p < 0.05) in patients who experienced delayed cerebral ischemia with fixed neurological deficits compared with those in other patients (post-SAH Days 0–5, 3.1 ± 0.8 pg/ml compared with 2.1 ± 0.2 pg/ml; post-SAH Days 6–14, 2.5 ± 0.4 pg/ml compared with 1.9 ± 0.2 pg/ml). Patients with angiographic evidence of severe vasospasm also had significantly (p < 0.05) elevated ET concentrations (post-SAH Days 0–5, 3.2 ± 0.8 pg/ml; post-SAH Days 6–14, 2.7 ± 0.5 pg/ml) as did those with a cerebral infarction larger than a lacuna on the follow-up CT scan (post-SAH Days 0–5, 3.1 ± 0.8 pg/ml; post-SAH Days 6–14, 2.5 ± 0.4 pg/ml) compared with other patients. Patients in whom angiography revealed diffuse moderate-to-severe vasospasm had significantly (p < 0.05) higher ET levels than other patients within 24 hours before or after angiography (2.6 ± 0.3 compared with 1.9 ± 0.2 pg/ml). In addition, patients with a history of hypertension or cigarette smoking experienced cerebral infarctions significantly more often than other patients, although angiography did not demonstrate severe or diffuse vasospasm more often in these patients than in others.Conclusions. Endothelin concentrations seem to correlate with delayed cerebral ischemia and vasospasm after SAH. The highest levels of ET are predictive of the symptoms of cerebral ischemia and vasospasm, and ET may also worsen ischemia in patients with a history of hypertension. Thus, ET may be an important causal or contributing factor to vasospasm, but its significance in the pathogenesis of vasospasm remains unknown.

A fatal, chronically growing basilar artery: a new type of dissecting aneurysm

1996 ◽  
Vol 84 (6) ◽  
pp. 962-971 ◽  
Author(s):  
Tohru Mizutani
Keyword(s):  
Mr Imaging ◽  
Basilar Artery ◽  
Dissecting Aneurysm ◽  
Neurological Deficits ◽  
Vertebrobasilar Insufficiency ◽  
Content Type ◽  
Asymptomatic Patients ◽  
Basilar Arteries ◽  
Fine Print

✓ A long-term follow-up study (minimum duration 2 years) was made of 13 patients with tortuous dilated basilar arteries. Of these, five patients had symptoms related to the presence of such arteries. Symptoms present at a very early stage included vertebrobasilar insufficiency in two patients, brainstem infarction in two patients, and left hemifacial spasm in one patient. Initial magnetic resonance (MR) imaging in serial slices of basilar arteries obtained from the five symptomatic patients showed an intimal flap or a subadventitial hematoma, both of which are characteristic of a dissecting aneurysm. In contrast, the basilar arteries in the eight asymptomatic patients did not show particular findings and they remained clinically and radiologically silent during the follow-up period. All of the lesions in the five symptomatic patients gradually grew to fantastic sizes, with progressive deterioration of the related clinical symptoms. Dilation of the basilar artery was consistent with hemorrhage into the “pseudolumen” within the laminated thrombus, which was confirmed by MR imaging studies. Of the five symptomatic patients studied, two died of fatal subarachnoid hemorrhage (SAH) and two of brainstem compression; the fifth patient remains alive without neurological deficits. In the three patients who underwent autopsy, a definite macroscopic double lumen was observed in both the proximal and distal ends of the aneurysms within the layer of the thickening intima. Microscopically, multiple mural dissections, fragmentation of internal elastic lamina (IEL), and degeneration of media were diffusely observed in the remarkably extended wall of the aneurysms. The substantial mechanism of pathogenesis and enlargement in the symptomatic, highly tortuous dilated artery might initially be macroscopic dissection within a thickening intima and subsequent repetitive hemorrhaging within a laminated thrombus in the pseudolumen combined with microscopic multiple mural dissections on the basis of a weakened IEL. The authors note and caution that symptomatic, tortuous dilated basilar arteries cannot be overlooked because they include a group of malignant arteries that may grow rapidly, resulting in a fatal course.

Progressive neurological deficits with benign intracerebral cysts

1986 ◽  
Vol 65 (5) ◽  
pp. 706-709 ◽  
Author(s):  
Yoko Nakasu ◽  
Jyoji Handa ◽  
Kazuyoshi Watanabe
Keyword(s):  
Histological Examination ◽  
Computerized Tomography ◽  
Cyst Wall ◽  
Benign Lesion ◽  
Ct Scanning ◽  
Neurological Deficits ◽  
Review Of The Literature ◽  
Content Type ◽  
Ct Findings ◽  
Fine Print

✓ Two patients with benign intracerebral cysts are reported and a brief review of the literature is given. Although computerized tomography (CT) scanning is useful in detecting a variety of intracerebral cysts, the CT findings are not specific for any lesion. An exploratory operation with establishment of an adequate route of drainage and a histological examination of the cyst wall are mandatory in the management of patients with a progressive but benign lesion.

Split spinal cord malformations in children

1998 ◽  
Vol 88 (1) ◽  
pp. 57-65 ◽  
Author(s):  
Yusuf Ersşahin ◽  
Saffet Mutluer ◽  
Sevgül Kocaman ◽  
Eren Demirtasş
Keyword(s):  
Spinal Cord ◽  
Neurological Deficits ◽  
Single Type ◽  
Type I ◽  
Type Ii ◽  
Content Type ◽  
Spinal Lesion ◽  
The Mean ◽  
Fine Print

Object. The authors reviewed and analyzed information on 74 patients with split spinal cord malformations (SSCMs) treated between January 1, 1980 and December 31, 1996 at their institution with the aim of defining and classifying the malformations according to the method of Pang, et al. Methods. Computerized tomography myelography was superior to other radiological tools in defining the type of SSCM. There were 46 girls (62%) and 28 boys (38%) ranging in age from less than 1 day to 12 years (mean 33.08 months). The mean age (43.2 months) of the patients who exhibited neurological deficits and orthopedic deformities was significantly older than those (8.2 months) without deficits (p = 0.003). Fifty-two patients had a single Type I and 18 patients a single Type II SSCM; four patients had composite SSCMs. Sixty-two patients had at least one associated spinal lesion that could lead to spinal cord tethering. After surgery, the majority of the patients remained stable and clinical improvement was observed in 18 patients. Conclusions. The classification of SSCMs proposed by Pang, et al., will eliminate the current chaos in terminology. In all SSCMs, either a rigid or a fibrous septum was found to transfix the spinal cord. There was at least one unrelated lesion that caused tethering of the spinal cord in 85% of the patients. The risk of neurological deficits resulting from SSCMs increases with the age of the patient; therefore, all patients should be surgically treated when diagnosed, especially before the development of orthopedic and neurological manifestations.

Retrosigmoid intradural suprameatal approach to Meckel's cave and the middle fossa: surgical technique and outcome

2000 ◽  
Vol 92 (2) ◽  
pp. 235-241 ◽  
Author(s):  
Madjid Samii ◽  
Marcos Tatagiba ◽  
Gustavo A. Carvalho
Keyword(s):  
Tumor Resection ◽  
Neurological Deficits ◽  
Subtotal Resection ◽  
Middle Fossa ◽  
Meckel’S Cave ◽  
Content Type ◽  
Simpson Grade ◽  
Petroclival Meningiomas ◽  
Meckel's Cave ◽  
Fine Print

Object. The goal of this study was to determine whether some petroclival tumors can be safely and efficiently treated using a modified retrosigmoid petrosal approach that is called the retrosigmoid intradural suprameatal approach (RISA).Methods. The RISA was introduced in 1983, and since that time 12 patients harboring petroclival meningiomas have been treated using this technique. The RISA includes a retrosigmoid craniotomy and drilling of the suprameatus petrous bone, which is located above and anterior to the internal auditory meatus, thus providing access to Meckel's cave and the middle fossa.Radical tumor resection (Simpson Grade I or II) was achieved in nine (75%) of the 12 patients. Two patients underwent subtotal resection (Simpson Grade III), and one patient underwent complete resection of tumor at the posterior fossa with subtotal resection at the middle fossa. There were no deaths or severe complications in this series; all patients did well postoperatively, being independent at the time of their last follow-up examinations (mean 5.6 years). Neurological deficits included facial paresis in one patient and worsening of hearing in two patients.Conclusions. Theapproach described here is a useful modification of the retrosigmoid approach, which allows resection of large petroclival tumors without the need for supratentorial craniotomies. Although technically meticulous, this approach is not time-consuming; it is safe and can produce good results. This is the first report on the use of this approach for petroclival meningiomas.

Dose-dependent epidural leakage of polymethylmethacrylate after percutaneous vertebroplasty in patients with osteoporotic vertebral compression fractures

2002 ◽  
Vol 96 (1) ◽  
pp. 56-61 ◽  
Author(s):  
Kyung Sik Ryu ◽  
Chun Kun Park ◽  
Moon Chan Kim ◽  
Joon Ki Kang
Keyword(s):  
Pain Relief ◽  
Epidural Space ◽  
Percutaneous Vertebroplasty ◽  
Vertebral Compression Fractures ◽  
Osteoporotic Vertebral Compression Fractures ◽  
Content Type ◽  
Compression Fractures ◽  
Dose Dependent ◽  
Pmma Cement ◽  
Fine Print

Object. The use of polymethylmethacrylate (PMMA) cement by percutaneous injection in cases requiring vertebroplasty provides pain relief in the treatment of osteoporotic vertebral compression fractures. A retrospective study was performed to assess what caused PMMA cement to leak into the epidural space and to determine if this leakage caused any changes in its therapeutic benefits. Methods. Polymethylmethacrylate was injected into 347 vertebral compression fractures in 159 patients. The cement leaked into the epidural space in 92 (26.5%) of 347 treated vertebrae in 64 (40.3%) of the 159 patients, as demonstrated on postoperative computerized tomography scanning. Epidural leakage of PMMA cement occurred more often when injected above the level of T-7 (p = 0.001) than below. The larger the volume of PMMA injected the higher the incidence of epidural leakage (p = 0.03). Using an injector also increased epidural leakage (p = 0.045). The position of the needle tip within the vertebral body and the pattern of venous drainage did not affect epidural leakage of the cement. Leakage of PMMA into the epidural space reduced the pain relief expected after vertebroplasty. The immediate postoperative visual analog scale scores were higher (and therefore reflective of less pain relief) in patients in whom epidural PMMA leakage occurred (p = 0.009). Three months postoperatively, the authors found the highest number of patients presenting with pain relief, including those in the group with epidural leakage, and at this follow-up stage there were no significant differences between the two groups. Conclusions. The authors found that epidural leakage of PMMA after percutaneous vertebroplasty was dose dependent. The larger amount of injected PMMA, the higher the incidence of leakage. Injecting vertebral levels above T-7 also increased the incidence of epidural leakage. Epidural leakage of PMMA may attenuate only the immediate therapeutic effects of vertebroplasty.

Combined effect of L-arginine and superoxide dismutase on the spastic basilar artery after subarachnoid hemorrhage in dogs

1994 ◽  
Vol 80 (3) ◽  
pp. 476-483 ◽  
Author(s):  
Yasukazu Kajita ◽  
Yoshio Suzuki ◽  
Hirofumi Oyama ◽  
Toshihiko Tanazawa ◽  
Masakazu Takayasu ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Superoxide Dismutase ◽  
Subarachnoid Hemorrhage ◽  
Basilar Artery ◽  
Superoxide Anion ◽  
Content Type ◽  
Vasodilator Effect ◽  
Intracisternal Injection ◽  
Dose Dependent ◽  
Fine Print

✓ To investigate the function of nitric oxide (a major endothelium-derived relaxing factor) in cerebral arteries after subarachnoid hemorrhage (SAH) in vivo, several nitric oxide-related substances were administered to dogs that had undergone double SAH. These included L-arginine (a substrate for the formation of nitric oxide), NG-monomethyl-L-arginine (L-NMMA, an analog of L-arginine that inhibits the formation of nitric oxide from L-arginine), and superoxide dismutase (SOD, which protects nitric oxide from oxidation by superoxide anion), which were given via intracisternal injection. The diameter of the basilar artery was assessed angiographically. In intact dogs, intracisternal bolus injections of L-arginine (1, 10, or 100 µmol) produced a dose-dependent increase in the internal diameter of the basilar artery; conversely, L-NMMA reduced the diameter of the basilar artery from baseline in a dose-dependent manner. On Days 4 and 7, after two intracisternal injections of autologous blood, L-arginine produced transient vasodilation of the spastic basilar artery, whereas L-NMMA produced no significant vasoconstriction. The vasodilator effect of L-arginine after SAH was stronger on Day 4 than on Day 7, but less than in intact dogs. Intracisternal injection of SOD, which caused no effect per se, enhanced the duration of the vasodilator effect of L-arginine on the basilar artery on Day 4 and both the magnitude and duration of that effect on Day 7. Thus, the basal release of nitric oxide was impaired after SAH, but the ability to synthesize nitric oxide in the vascular wall was not abolished. The finding that the simultaneous injection of SOD enhanced and prolonged the vasodilation induced by sufficient exogenous L-arginine suggests that the inactivation of nitric oxide by superoxide anion contributes to the development of vasospasm.

Transcranial electrical stimulation through screw electrodes for intraoperative monitoring of motor evoked potentials

2004 ◽  
Vol 100 (1) ◽  
pp. 155-160 ◽  
Author(s):  
Katsushige Watanabe ◽  
Takashi Watanabe ◽  
Akio Takahashi ◽  
Nobuhito Saito ◽  
Masafumi Hirato ◽  
...  
Keyword(s):  
Electrical Stimulation ◽  
Motor Cortex ◽  
Evoked Potentials ◽  
Intraoperative Monitoring ◽  
Primary Motor Cortex ◽  
Motor Evoked Potentials ◽  
Transcranial Electrical Stimulation ◽  
Content Type ◽  
Motor Pathways ◽  
Fine Print

✓ The feasibility of high-frequency transcranial electrical stimulation (TES) through screw electrodes placed in the skull was investigated for use in intraoperative monitoring of the motor pathways in patients who are in a state of general anesthesia during cerebral and spinal operations. Motor evoked potentials (MEPs) were elicited by TES with a train of five square-wave pulses (duration 400 µsec, intensity ≤ 200 mA, frequency 500 Hz) delivered through metal screw electrodes placed in the outer table of the skull over the primary motor cortex in 42 patients. Myogenic MEPs to anodal stimulation were recorded from the abductor pollicis brevis (APB) and tibialis anterior (TA) muscles. The mean threshold stimulation intensity was 48 ± 17 mA for the APB muscles, and 112 ± 35 mA for the TA muscles. The electrodes were firmly fixed at the site and were not dislodged by surgical manipulation throughout the operation. No adverse reactions attributable to the TES were observed. Passing current through the screw electrodes stimulates the motor cortex more effectively than conventional methods of TES. The method is safe and inexpensive, and it is convenient for intraoperative monitoring of motor pathways.

Tethered cord syndrome in children with anorectal malformations

2000 ◽  
Vol 92 (4) ◽  
pp. 626-630 ◽  
Author(s):  
Natarajan Muthukumar ◽  
Bhuvaneswari Subramaniam ◽  
Thangaraj Gnanaseelan ◽  
Ramesh Rathinam ◽  
Appaswamy Thiruthavadoss
Keyword(s):  
Tethered Cord ◽  
Anorectal Malformations ◽  
Neurological Deficits ◽  
Radiographic Evidence ◽  
Content Type ◽  
X Ray ◽  
Neurological Improvement ◽  
Intraspinal Anomalies ◽  
Bone Abnormalities ◽  
Fine Print

Object. Anorectal malformations are known to be associated with neurological deficits, which may contribute to the disability suffered by patients with these malformations. This study was undertaken to determine the incidence and pattern of sacral abnormalities in children with anorectal malformations, the incidence and nature of the neurological deficits, and the incidence and nature of operable intraspinal abnormalities in patients with this condition.Methods. Neurological evaluation was performed in 81 children with anorectal malformations. Plain x-ray films were obtained to identify the presence of sacral abnormalities. The patients with neurological deficits were evaluated for the presence of operable intraspinal anomalies, and when such anomalies were identified, correction of the same was undertaken. In 21% of these children radiographic evidence of sacral abnormalities was shown. Fifteen percent of patients harbored neurological deficits, and 10% harbored operable intraspinal anomalies. In addition, one patient had split notochord syndrome. Patients with operable intraspinal anomalies underwent surgical correction, with resultant neurological improvement.Conclusions. Bone abnormalities of the sacrum, neurological deficits, and operable intraspinal lesions are not uncommon in children with anorectal malformations. Because the neurological deficits can contribute to the disability suffered by these individuals, we recommend routine screening of patients with anorectal malformations and neurological deficits and/or sacral abnormalities for the early identification and treatment of potentially correctable intraspinal lesions.

scholarly journals Pharmacokinetic-Pharmacodynamic Assessment of the Hepatic and Bone Marrow Toxicities of the New Trypanoside Fexinidazole

2019 ◽  
Vol 63 (4) ◽  
Author(s):  
James A. Watson ◽  
Nathalie Strub-Wourgraft ◽  
Antoine Tarral ◽  
Isabela Ribeiro ◽  
Joel Tarning ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Chagas Disease ◽  
Plasma Concentrations ◽  
Bone Marrow Suppression ◽  
Population Pharmacokinetic ◽  
Phase 2 ◽  
Content Type ◽  
Platelet Counts ◽  
Exposure Response ◽  
Dose Dependent

ABSTRACT Fexinidazole is a novel oral treatment for human African trypanosomiasis caused by Trypanosoma brucei gambiense (g-HAT). Fexinidazole also has activity against T. cruzi, the causative agent of Chagas disease. During the course of a dose ranging assessment in patients with chronic indeterminate Chagas disease, delayed neutropenia and significant increases in hepatic transaminases were observed and clinical investigations were suspended. We retrospectively analyzed all available pharmacokinetic and pharmacodynamic data on fexinidazole in normal healthy volunteers and in patients with Chagas disease and g-HAT to assess the determinants of toxicity. A population pharmacokinetic model was fitted to plasma concentrations (n = 4,549) of the bioactive fexinidazole sulfone metabolite, accounting for the majority of the bioactive exposure, from three phase 1 studies, two g-HAT phase 2/3 field trials, and one Chagas disease phase 2 field trial (n = 462 individuals in total). Bayesian exposure-response models were then fitted to hematological and liver-related pharmacodynamic outcomes in Chagas disease patients. Neutropenia, reductions in platelet counts, and elevations in liver transaminases were all found to be exposure dependent and, thus, dose dependent in patients with Chagas disease. Clinically insignificant transient reductions in neutrophil and platelet counts consistent with these exposure-response relationships were observed in patients with g-HAT. In contrast, no evidence of hepatotoxicity was observed in patients with g-HAT. Fexinidazole treatment results in a dose-dependent liver toxicity and transient bone marrow suppression in Chagas disease patients. Regimens of shorter duration should be evaluated in clinical trials with patients with Chagas disease. The currently recommended regimen for sleeping sickness provides exposures within a satisfactory safety margin for bone marrow suppression and does not cause hepatotoxicity.

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