Toshiyuki Tobita

Diagnosis of Spinal Disease with Ultrafine Flexible Fiberscopes in Patients with Chronic Pain

Study Design. Spinal epidural and subarachnoid spaces were observed with the newly developed fine flexible fiberscopes in 55 patients with chronic pain. Objectives. To evaluate the fiberscopes as diagnostic tools for spinal canal disease. Summary of Background Data. Fine flexible fiberscopes make it possible to visualize the entire length of the spinal subarachnoid space without major complications, and they may be of value for the diagnosis of certain spinal canal diseases. Methods. The epidural and subarachnoid spaces were accessed by fine flexible fiberscopes (Purely Fine [PF] types) in the initial 45 patients and by those equipped with a tip-steering function and a working channel (Medical Science [MS] types) in the later 10 patients, respectively. The procedures were based on those of continuous epidural or subarachnoid block. Results. Normal and abnormal subarachnoid spaces were clearly observed. When the MS types were used, the intended sites of the spinal structures could be more easily approached. In 12 patients, new diagnoses were made (chronic arachnoiditis 9, subarachnoid cyst 2, old subdural hematoma 1) that could not be found by magnetic resonance imaging or computed tomography. Additionally, chronic arachnoiditis was found in 2 patients with spinal trauma. Pathologic changes were confirmed by fiberscopic examination in 16 patients (arachnoiditis 11, spinal trauma 2, arteriovenous malformation 2, subarachnoid cyst 1). No pathologic changes could be detected in 27 patients with spinal canal stenosis, disc herniation, reflex sympathetic dystrophy, or posttraumatic pain syndrome. There were no significant differences in incidence of new diagnoses between the PF and MS types of fiberscopes. There were no major complications. There were 2 cases of light fever in the initial 10 patients and 7 cases of headache in the initial 14 patients. Only 4 cases of headache were observed in the subsequent 41 patients, in whom 20 mL of saline was injected into the epidural space. Conclusion. These fine flexible fiberscopes may provide new diagnostic and interventional tools for spinal canal diseases, provided skilled techniques are applied.

Propofol enhances GABAA receptor-mediated presynaptic inhibition in human spinal cord

Although the function of somatodendritic GABAA receptors is augmented by propofol, it is not known whether presynaptic GABAA receptor function is similarly affected. In the present study, we examined the action of propofol on the second positive wave (P2 component) of segmental spinal cord evoked potentials (seg SCEPs), which is believed to reflect GABAA receptor-mediated presynaptic inhibition of primary afferent terminals and can be recorded from spinal epidural space in man. In all seven patients tested while undergoing scoliosis surgery, a clinical dose of propofol (1 mg//kg, i.v.) significantly augmented the P2 component of seg SCEPs evoked by ulner nerve stimulation. We conclude that propofol enhances GABAA receptor-mediated presynaptic inhibition at primary afferent terminals in human spinal cord.

Spinal tracts producing slow components of spinal cord potentials evoked by descending volleys in man

Slow negative (N) and slow positive (P) waves are frequently produced in the posterior epidural space at the lumbosacral enlargement by epidural stimulation of the rostral part of human spinal cord. The production of these slow potentials are thought to be responsible for analgesia at the stimulated segment as well as below that level. In order to define the spinal tract which mediates these slow potentials, we stimulated directly or from the epidural space the dorsal, dorsolateral, lateral and ventral columns at the cervical or thoracic level, and epidurally recorded spinal cord potentials (des.SCPs) at the lumbosacral enlargement in 7 patients who underwent spine or spinal cord surgery. The des.SCPs recorded in the lumbosacral enlargement consisted of polyphasic spike potentials followed by slow N and P waves. At a near threshold level of stimulus intensity the slow N and P potentials were consistently elicited only by stimulation of the dorsal column. The slow waves were also produced by intense stimulation of other tracts, but remained significantly (P < 0.05 - P < 0.01) smaller than those evoked by dorsal column stimulation when compared at the same stimulus intensity. Moreover, the slow P wave could not be elicited even by intense stimulation (10 times the threshold strength for the initial spike potentials) of the ventral column. Thus, the results suggest that the slow N and P waves are mostly mediated by the antidromic impulses descending through the dorsal column.

Aortic aneurysm in a four-year-old child with tuberous sclerosis.

We present a case of aortic aneurysm in a four‐year‐old child complicated with tuberous sclerosis. We used the same general principles as for adult patients and successfully managed our patient. Our methods included the use of isoflurane plus epidural anaesthesia, dopamine to maintain blood pressure, and induced mild hypothermia to reduce brain metabolism and to prevent spinal cord damage during aortic cross‐clamping. Intensive monitoring including EEG was beneficial to the anaesthetic management.

Erb's point stimulation produces slow positive potentials in the human lumbar spinal cord.

Evoked spinal cord potentials (SCPs) were recorded from the posterior epidural space (PES) at the cervical and lumbrosacral enlargements in response to electrical stimulation of the brachial plexus at Erbs point in 17 chronic pain patients. Erbs point stimulation produced slow positive potentials (heterosegmental slow positive potentials, HSPs) in the PES at the lumbrosacral enlargement in all 13 subjects without spinal cord lesions but not in 4 subjects with spinal cord lesions. The HSP1 with a central peak latency of 21 +/- 2 ms (mean +/- SE) was recorded at the stimulus intensity up to two to three times the threshold strength (T) of the initially positive spike (P1) of the segmental SCP, which was simultaneously recorded from the PES at the cervical enlargement. At the stimulus intensity of more than 3T, another slow positive potential (HSP2) with central peak latency of 71 +/- 6 ms was recorded. These slow positive potentials (HSP1 and HSP2) might be produced by a feedback loop via supraspinal structures, presumably primary afferent depolarizations, in comparison to the HSPs of our previous studies in the rat. Slow negative potentials were sometimes noted before (5 of 13) and/or after (2 of 13) the HSP1. These slow negative potentials probably reflect the activities of dorsal horn neurons producing the HSP1 and HSP2, respectively, also elicited by a feedback loop via supraspinal structures.

Free radical scavenger edaravone produces robust neuroprotection in a rat model of spinal cord injury

We used a multimodal approach to evaluate the effects of edaravone in a rat model of spinal cord injury (SCI). SCI was induced by extradural compression of thoracic spinal cord. In experiment 1, 30 min prior to compression, rats received a 3 mg/kg intravenous bolus of edaravone followed by a maintenance infusion of 1 (low-dose), 3 (moderate-dose), or 10 (high-dose) mg/kg/h edaravone. Although both moderate- and high-dose edaravone regimens promoted recovery of spinal motor-evoked potentials (MEPs) at 2 h post-SCI, the effect of the moderate dose was more pronounced. In experiment 2, moderate-dose edaravone was administered 30 min prior to compression, at the start of compression, or 10 min after decompression. Although both preemptive and coincident administration resulted in significantly improved spinal MEPs at 2 h post-SCI, the effect of preemptive administration was more pronounced. A moderate dose of edaravone resulted in significant attenuation of lipid peroxidation, as evidenced by lower concentrations of the free radical malonyldialdehyde in the spinal cord 3 h post-SCI. Malonyldialdehyde levels in the high-dose edaravone group were not reduced. Both moderate- and high-dose edaravone resulted in significant functional improvements, evidenced by better Basso-Beattie-Bresnahan (BBB) scores and better performance on an inclined plane during an 8 week period post-SCI. Both moderate- and high-dose edaravone significantly attenuated neuronal loss in the spinal cord at 8 weeks post-SCI, as evidenced by quantitative immunohistochemical analysis of NeuN-positive cells. In conclusion, early administration of a moderate dose of edaravone minimized the negative consequences of SCI and facilitated functional recovery.

Anaesthesia and orphan disease: marked attenuation of motor evoked potentials by high-dose dexmedetomidine in a child with Angelman syndrome undergoing scoliosis surgery: A case report with pharmacokinetic analysis.

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Thiamylal antagonizes the inhibitory effects of dorsal column stimulation on dorsal horn activities in humans.

In humans, peripheral somatosensory information converges upon dorsal horn neurons in the spinal cord, which can be recorded from the dorsal epidural space as spinal cord potentials (SCPs) following segmental dorsal root stimulation (SS) employing epidural catheter electrodes. Antidromic action potentials and descending inhibition from the dorsolateral funiculus may contribute to SCPs following dorsal column stimulation (DCS). Effects of thiamylal (2.5-7.5 mg/kg, i.v.) on SCPs evoked by independent DCS or SS were compared with those evoked by simultaneous DCS and SS (DCS/SS). DCS- and SS-evoked SCPs recorded from the lumbar enlargement consisted of a sharp negative (N) followed by a slow positive (P) potential. Thiamylal induced dose-dependent increases in amplitude and duration of both N and P potentials evoked by DCS and SS, whether the responses were summed or evoked simultaneously. In awake subjects, N and P potentials produced by simultaneous DCS/SS were significantly smaller than the sum of independent responses. Thiamylal anesthesia antagonized this inhibition; responses to simultaneous DCS/SS were larger than the sum of independent responses. These results suggest that in wakefulness DCS inhibits dorsal horn neuron activity in the lumbar spinal cord, while thiamylal antagonizes DCS-induced inhibition in dose-dependent fashion.

Transcranial Magnetically Evoked SCPs (TCM-Evoked SCPs)

Spinal cord function monitoring during spine or spinal cord surgery has been carried out mostly with the use of somatosensory evoked potentials (SEPs) induced by peripheral nerve stimulation and recorded from the scalp (Grundy and Villani, 1988; McPherson and Ducker, 1988). The scalp SEPs, however, do not directly reflect the activities of the motor system, and surgical manipulations of the spine or spinal cord often affect the motor systems without producing SEP abnormalities (Ginsburg et al., 1985; Ben-David et al., 1987). Motor-evoked potentials from the peripheral muscles (motor-evoked electromyograms, or EMGs) induced by transcranial magnetic (Barker and Jalinous, 1985) or electrical (Merton and Morton, 1980) stimulation were developed, and might have advantages over SEPs during surgery in which manipulations of the motor tracts are predicted (Kawaguchi and Furuya, 2004).

Anesthetic management in a patient with giant growing teratoma syndrome: a case report

IntroductionGrowing teratoma syndrome is a rare occurrence with an ovarian tumor. Anesthesia has been reported to be difficult in cases of growing teratoma syndrome of the cystic type due to the pressure exerted by the tumor. However, there have been no similar reports with the solid mass type. Here, we report our experience of anesthesia in a case of growing teratoma syndrome of the solid type.Case presentationThe patient was a 30-year-old Japanese woman who had been diagnosed with an ovarian immature teratoma at age 12 and had undergone surgery and chemotherapy. However, she dropped out of treatment. She presented to our hospital with a 40cm giant solid mass and severe respiratory failure, and was scheduled for an operation. We determined that we could not obtain a sufficient tidal volume without spontaneous respiration. Therefore, we chose to perform awake intubation and not to use a muscle relaxant before the operation. At the start of the operation, when muscle relaxant was first administered, we could not obtain a sufficient tidal volume. An abdominal midline incision was performed immediately and her tidal volume recovered. Her resected tumor weighed 10.5kg. After removal of her tumor, her tidal volume was maintained at a level consistent with that under spontaneous respiration to avoid occurrence of re-expansion pulmonary edema.ConclusionsWe performed successful anesthetic management of a case of growing teratoma syndrome with a giant abdominal tumor. Respiratory management was achieved by avoiding use of a muscle relaxant before the operation to maintain spontaneous respiration and by maintaining a relatively low tidal volume, similar to that during spontaneous respiration preoperatively, after removal of the tumor to prevent re-expansion pulmonary edema.