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V Deletis

Publications and source records attributed to V Deletis.

At least 37 records · Page 2Linked to original sources
PubMed1997

Intraspinal sarcoidosis: diagnosis and management.

OBJECTIVE: Isolated intramedullary spinal cord or cauda equina involvement by sarcoidosis is quite rare. We report three patients with intraspinal sarcoidosis and absent systemic manifestations of the disease. The clinical presentation, operative management, electrophysiologic studies, pathology, laboratory investigations, and current therapy are discussed with attention to the previous literature. METHODS: Two of the three patients had a preoperative diagnosis of a cervical intramedullary spinal cord tumor. The third patient had the preoperative diagnosis of an infectious process involving the cauda equina. Magnetic resonance imaging (MRI) with gadolinium did not suggest an inflammatory process. Intraoperative somatosensory evoked potential performed in two patients exhibited normal amplitudes, but a prolonged latency in seven out of eight extremities; with normal central conduction time suggesting a peripheral or radicular involvement. All three patients underwent laminectomy and biopsy of the intraspinal pathology. RESULTS: Pathologic examination demonstrated sarcoidosis in all three patients. Intraoperative observations, intramedullary nodules, and thickening of the meninges were inconsistent with neoplasm and limited the surgical procedure to a biopsy. Frozen sections performed at two of the operations revealed an inflammatory process that confirmed the intraoperative observations. Postoperatively, the diagnostic work-up for all patients was negative for systemic manifestations. CONCLUSIONS: Isolated intraspinal sarcoidosis is a rare process. The current management for intramedullary spinal cord or cauda equina sarcoidosis is prolonged corticosteroids. The surgeon should not attempt complete resection if this granulomatous process is suspected.

Adult↗
PubMed1997

Intraoperative recording of the bulbocavernosus reflex.

OBJECTIVE: To demonstrate the feasibility of intraoperative monitoring of the bulbocavernosus reflex (BCR) as an indicator of the functional integrity of sacral nervous structures to aid in preventing their intraoperative injury. METHODS: Intraoperative BCR was elicited by electrical stimulation of the dorsal penile/clitoral nerve in 119 patients anesthetized with propofol, fentanyl, and nitrous oxide, with short-acting relaxant. Thirty-eight patients underwent surgery without risk, whereas 81 underwent surgery with risk of damage to sacral structures. Different patterns of stimuli were applied through silver/silver chloride disc electrodes placed on the dorsal aspect of the penis in males and over the clitoris (cathode) and adjacent labia (anode) in females. Recordings were made from the anal sphincter using intramuscular wire electrodes introduced within a 27.5 gauge needle, with two electrodes each inserted in the right and left hemisphincter muscles. Preoperatively, some patients had minor urinary problems in controlling their sphincters. RESULTS: The BCR was reliably recorded without habituation under this anesthetic regime. Optimal stimulating parameters were found to be double pulses (0.5-ms duration), with an interstimulus interval of 3 ms, stimulating rate of 2.3 Hz, and intensity of 20 mA. With these parameters, it was possible to record the BCR intraoperatively in all patients. Isoflurane and nitrous oxide significantly suppressed the BCR, and muscle relaxant completely abolished it. CONCLUSION: We demonstrated that it is feasible, under certain anesthetic regimes, to intraoperatively monitor the BCR in both children and adults (24 d to 74 yr of age) who did not have significantly affected function in sacral nervous structures.

Adolescent↗
PubMed1997

Preservation of pudendal afferents in sacral rhizotomies.

OBJECTIVE: To assess the effectiveness of pudendal afferent mapping as a tool to minimize the risk of postoperative bowel, bladder, and sexual dysfunction in patients undergoing selective posterior rhizotomies in whom the S2 roots are candidates for rhizotomy. METHODS: One-hundred fourteen children with the diagnosis of cerebral palsy and debilitating spasticity were selected to undergo selective posterior rhizotomies at New York University Medical Center during 1991 through 1995. There were 72 male and 42 female patients with a mean age of 3.8 years. At the time of surgery, none of the patients had clinically relevant bladder dysfunction. Dorsal root action potentials were recorded intraoperatively to map the distribution of pudendal afferent fibers in S1-S3 roots bilaterally before performing the rhizotomies. RESULTS: Pudendal afferent mapping was successful in 105 of 114 patients. In the majority of these patients (56%), the distribution was asymmetrical. S1 roots contributed 4%, S2 roots 60.5%, and S3 roots 35.5% of the overall pudendal afferent activity. The pudendal afferent distribution was often confined to a single level in 18% of the patients or even to a single root in 7.6%. Fifty-six percent of the pathologically responding S2 roots during rhizotomy testing were preserved because of the significant afferent activity, as demonstrated during pudendal mapping. None of the 105 patients so mapped developed long-term bowel or bladder complications. CONCLUSIONS: Pudendal afferent mapping identifies S2 roots that carry a significant number of fibers involved with genital sensation. The preservation of such roots during surgical procedures may be important for sexual function and may also contribute to decreasing postoperative bladder and bowel disturbances.

Action Potentials↗
PubMed1997

The role of motor evoked potentials during surgery for intramedullary spinal cord tumors.

OBJECTIVE: This is a prospective study of the methodology and clinical applications of motor evoked potentials (MEPs) during surgery for intramedullary spinal cord tumors. METHODS: Transcranial electrical stimulation was used to activate corticospinal motoneurons, and the traveling waves of the spinal cord were recorded through catheter-electrodes placed epi- or subdurally. Intraoperative MEP monitoring was performed in 32 consecutive patients (age range, 1-50 yr) undergoing resection of intramedullary spinal cord tumors. In 19 patients, MEPs were present before myelotomy (monitorable group), and in 10 patients, MEPs were absent before myelotomy (unmonitorable group). Placement of an epidural electrode was not possible in two patients, and technical problems prevented recording in one. RESULTS: MEP amplitudes decreased intraoperatively by more than 50% of baseline in three patients, all of whom had postoperative paraplegia. Two of these patients recovered within 1 week after surgery, and one remained paraplegic. None of the patients with preserved MEP amplitude (> 50%) sustained immediate significant postoperative deterioration. Motor function was significantly deteriorated 1 week after surgery in one patient in the monitorable group and in five patients in the unmonitorable group. MEP monitorability was significantly associated with good surgical outcome for adult patients (P < 0.05), although not for pediatric patients (P > 0.6). Preoperative motor status and surgical outcome were not significantly associated for the adult (P = 0.13) or pediatric groups (P > 0.4). CONCLUSION: MEP monitorability was a better predictor of functional outcome than the patient's preoperative motor status for the adult group. Significant predictors of MEP monitorability in the adult group were preoperative motor function (P < 0.01), history of no previous treatment (surgery or irradiation) (P < 0.01), and small tumor size (P < 0.05). Weak associations with monitorable MEPs existed for low-grade tumors (P = 0.09), the presence of baseline somatosensory evoked potentials (P = 0.10), and tumor pathological abnormalities (ependymoma) (P = 0.13). No associations were determined for sex (P > 0.4), associated syrinx (P > 0.3), or tumor location (P > 0.5). In the pediatric group, none of the examined factors were associated with MEP monitorability (P > 0.3). A decline of more than 50% in MEP amplitude during tumor removal should serve as a serious warning sign to the surgeon.

Child↗
PubMed1997

Intraoperative spinal cord monitoring for intramedullary surgery: an essential adjunct.

Intraoperative monitoring of the functional integrity of the spinal cord during removal of intramedullary spinal cord lesions is an aid in intraoperative decision making and a primary tool for the prediction of neurological outcome. Motor evoked potential monitoring has become the neurophysiological monitoring technique of choice for that purpose. In the senior author's experience with over 130 pediatric patients suffering from intramedullary spinal cord tumors, the neurophysiological data of both motor and sensory evoked potentials was utilized in an integrative fashion. Motor evoked potentials, elicited with single transcranial electrical stimuli and recorded directly from the spinal cord with an electrode in the spinal epidural space, reflect the functional integrity of the corticospinal tract. Motor evoked potentials, elicited with a short train of transcranial electrical stimuli and recorded from limb muscles, reflect the functional integrity of the motor system from the cerebral cortex/white matter to beyond the neuromuscular junction. Both epidural and muscle motor evoked potentials correlated closely with postoperative neurological function. Both techniques provide fast, practical and reliable information on the functional integrity of the motor tracts of the spinal cord. No complications attributable to stimulation or recording occurred. Over time both the technique's reliable power of predicting clinical outcome and its practical versatility have altered the surgical approach in that gross total resections are more readily attempted as long as motor evoked potential data indicate the intact functional integrity of the corticospinal tract. This monitoring technique unquestionably had a favorable impact on neurological outcome.

Adolescent↗
PubMed1997

Intraoperative monitoring of spinal cord function using motor evoked potentials via transcutaneous epidural electrode during anterior cervical spinal surgery.

Because false-positive results are not infrequent when monitoring somatosensory evoked potentials during surgery, monitoring of motor evoked potentials (MEPs) has been proposed and successfully used during the removal of spinal cord tumors. However, this often requires direct visual placement of an epidural electrode after a laminectomy. We evaluated the use of MEPs, recorded via a transcutaneously placed epidural electrode, to monitor motor pathway functional integrity during surgery on the anterior cervical spine. Sixteen patients underwent anterior cervical vertebral decompression and fusion for cervical myelopathy and/or radiculopathy. Before surgery, an epidural monitoring electrode was placed transcutaneously at the midthoracic level and was used to record MEPs after transcranial cortical electrical stimulation. Electrode placement was successful in all patients but one, and satisfactory baseline spinal MEPs were obtained except for one patient who had cerebral palsy with significant motor dysfunction. Patients showed no significant changes in spinal MEPs during surgery, and all had baseline or better motor function postoperatively. None had complications from epidural electrode placement or electrical stimulation. We conclude that motor pathways can be monitored safely during anterior cervical spinal surgery using spinal MEPs recorded via a transcutaneously placed epidural electrode, that MEP preservation during surgery correlates with good postoperative motor function, and that cerebral palsy patients may possess too few functional motor fibers to allow MEP recording.

Adolescent↗
PubMed1996

Spinal cord and nerve root monitoring in spine surgery and related procedures.

Intensive research in the field of intraoperative neurophysiologic monitoring has been performed directed at finding reliable stimulating and recording techniques and adequate anesthetic regimes applicable to spinal procedures. The aim is a comprehensive monitoring not only of afferent and efferent spinal cord pathways but also of sensory and motor nerve roots and cauda equina fibers. Conventional somatosensory evoked potentials (SEPs) are complemented by motor evoked potentials, dermatomal sensory evoked potentials, spinal cord evoked potentials, evoked electromyography, sensory and motor fiber mapping of the cauda equina, bulbocavernosus reflex testing, and neurogenic evoked potentials. Apart from describing the essentials of these techniques and their indications and limitations, this article deals with the influence of anesthetic management on the production and interpretation of evoked potentials.

Humans↗
PubMed1996

Motor evoked potentials during brain surgery.

In order to obtain a robust method for intraoperative monitoring of motor pathways, different stimulation patterns to elicit muscle motor evoked potentials (MEPs) were studied during neurosurgical procedures in 3 patients. MEPs were recorded by a catheter electrode in the subdural space and/or by needle electrodes in limb muscles. For stimulation single pulses and trains consisting of two to five pulses were used. Muscle MEPs were only obtained after trains of at least 3 stimuli while single/double stimuli were inefficient. Simultaneous subdural recordings showed that single and double stimuli only elicited D-waves, whereas trains of 3 or more stimuli generated I-waves, as well. We propose that train stimulation can overcome the depressive effects of anesthesia on cortical motoneurons.

Brain↗
PubMed1996

Functional anatomic relationship between brain-stem tumors and cranial motor nuclei.

OBJECTIVE: To identify patterns of cranial motor nuclei (CMN) displacement in cases of intramedullary brain stem tumor, using neurophysiological mapping of motor nuclei on the floor of the fourth ventricle. METHODS: Relationships between tumors and CMN were reviewed in 18 patients with brain stem tumors (seven pontine, nine medullary, and two pontomedullary tumors) and 2 with cervicomedullary junction spinal cord tumors. CMN VII, IX/X, and XII were mapped by applying electrical stimuli over the surgically exposed fourth ventricular floor through a handheld probe and recording electrical activity in the appropriate cranial muscles. RESULTS: Tumors distorted the anatomic location of CMN in repetitive patterns according to tumor site. Three patterns were identified as follows: Type 1, CMN located around the tumor on the floor of fourth ventricle; Type 2, one or more CMN located ventrally to the tumor; Type 3, CMN in original anatomic position. Six of seven patients with pontine tumors showed the Type 1 pattern. Seven of nine patients with medullary tumors showed Type 2, and the other two showed Type 1. Both patients with pontomedullary tumors showed Type 2. One patient with a cervicomedullary junction spinal cord tumor showed Type 1 and the other Type 3, depending on the tumor extension into the fourth ventricle. CONCLUSION: Pontine tumors push the CMN to around the tumor edge, suggesting that precise localization of CMN before tumor resection is necessary to avoid their damage. Medullary tumors grow more exophytically and compress the CMN ventrally. Understanding patterns of CMN displacement can help surgeons establish the surgical plan, minimize risks, and enable safer surgery of brain stem tumors.

Adolescent↗
PubMed1995

Introduction of magnetoencephalography to stereotactic techniques.

Magnetoencephalography (MEG), a noninvasive functional brain mapping technique, was used for preoperative localization of the sensorimotor cortex in patients harboring lesions involving these eloquent regions. Prior to surgery, MEG source locations were transferred onto high-resolution MRI pictures which were then used for preoperative evaluation, risk analysis, and planning. We have developed a process to transform the MEG-derived sensorimotor localization coordinates into the COMPASS stereotactic coordinate system. Thus the MEG-derived functional information is incorporated into the stereotactic database, enabling the simultaneous visualization of functional and anatomical data. This information can be used for the selection of cases and in planning safe approaches for computer-assisted volumetric resections. The integration of MEG and stereotactic neurosurgery also allows a more precise comparison between MEG and intraoperative direct electrocorticographic mapping (ECoG). Seven patients were studied with good correlation between MEG and intraoperative mapping. In 4, the correlation was only based on gross visual comparison between intraoperative identification of the gyrus pattern and MEG photographs. The availability of the MEG coordinates in the stereotactic system, however, allows a more precise correlation between MEG and ECoG. In all 3 patients studied in this manner, the MEG coordinates (pinpointed to a precise cortical representation of a few millimeters) overlapped with ECoG results. In summary, we compared functional MEG data to intraoperative ECoG and conclude that the introduction of MEG into stereotactic neurosurgery can provide precise functional and anatomic information for image-guided surgical planning and resection.

Brain Mapping↗
PubMed1995

Brain stem mapping: neurophysiological localization of motor nuclei on the floor of the fourth ventricle.

We have improved upon a brain stem mapping technique that can be used to locate cranial motor nuclei on the floor of the fourth ventricle. This technique helped to intraoperatively locate the facial colliculus and the motor nuclei of cranial nerves IX/X and XII in 14 patients undergoing removal of brain stem tumors. The motor nuclei of these cranial nerves are usually located relative to specific anatomic landmarks on the ventricular floor. These landmarks were not evident in most patients studied because of the distorting effects of the tumor. Different points of the floor of the fourth ventricle were electrically stimulated while electromyographic responses were recorded with electrodes inserted in the orbicularis oculi and orbicularis oris muscles, the lateral posterior pharyngeal wall, and the intrinsic muscles of tongue. Mapping was performed before and after tumor resection. The technique was found to be useful for locating cranial motor nuclei before tumor resection. It enabled surgeons to avoid damaging the nuclei when entering the brain stem. This technique, however, has certain limitations. Because this is a mapping technique, not a monitoring technique, continuous monitoring during tumor resection was unavailable. Also, the presence of a muscle response after tumor resection did not always indicate preservation of immediate postoperative function (7 days after surgery) because damage to the corticobulbar tract and/or the underlying neural circuitry was not detectable by mapping. Further research is needed to determine the point of stimulation in the functional motor circuitry and the relationship between intraoperative recordings and postoperative function in the long term.

Adolescent↗
PubMed1995

Electrodiagnosis in the management of brachial plexus surgery.

A few pre and intraoperative neurophysiological tests offer valuable information in the diagnosis and functional evaluation of brachial plexus injury. The tests and the questions they answer can guide the surgeon's decision about whether to perform neurolysis or an interpositional graft.

Brachial Plexus↗
PubMed1994

The use of motor evoked potentials in the diagnosis of psychogenic quadriparesis. A case study.

We present a case illustrating the usefulness of motor evoked potentials (MEPs) in differentiating psychogenic from organic postoperative paralysis. Discussed is a 12-year-old girl who underwent surgery for the repair of a recurrent syringomyelia. On the 6 day after a proximal revision of her syringoperitoneal shunt she returned to the hospital with deep quadriparesis, bowel and bladder incontinence, and complaining of severe headache. An MRI scan showed the syrinx to be collapsed, and removal of the shunt had no impact on her clinical symptoms. Repeat somatosensory evoked potentials (SEPs) showed no change in comparison to those obtained at the end of her preceding surgery. MEPs were normal for the lower extremities, a finding which is inconsistent with a severe upper motor neuron lesion. She was diagnosed with psychogenic paralysis, and fully recovered within 1 month. We propose that a neurophysiological evaluation including MEPs is useful in the differential diagnosis of psychogenic and organic motor weakness.

Child↗
PubMed1994

Inclusion of the S2 dorsal rootlets in functional posterior rhizotomy for spasticity in children with cerebral palsy.

Many neurosurgeons have made a practice of sectioning the S2 dorsal roots during selective posterior rhizotomy for the treatment of spasticity in children with cerebral palsy, but the efficacy of this treatment has not previously been proven. S2 afferents are involved in reflex arcs of the plantar flexors (PFs), so that S2 lesioning should in theory reduce PF spasticity. To test this assumption, we determined the frequency of postoperative residual spasticity in the PFs when S2 lesioning was or was not performed. We assessed 85 children for whom 6-month follow-up was available. Functional rhizotomy from L2-S1 was performed on 13 of them (26 legs with PF spasticity) and from L2-S2 on 72 (141 legs with PF spasticity). Rootlets were lesioned if there was an abnormal response to intraoperative electrical stimulation. In 20 patients, lesioning of the S2 rootlets was assisted by the "pudendal neurogram," a technique previously shown to prevent bladder dysfunction during sectioning of the sacral roots. When S2 roots were excluded from the lesioning process, residual PF spasticity was detected in 35% of the legs that had it preoperatively, leaving 5 (38%) of 13 children with functionally impairing spasticity. When S2 roots were included, 6% of legs that had PF spasticity retained it postoperatively (P < 0.001), leaving 8 (11%) of 72 patients with functionally limiting spasticity (P < 0.05). Thus, the addition of the S2 roots to the procedure resulted in an 81% reduction in the number of legs with residual PF spasticity and a 71% reduction in the number of patients with residual PF spasticity.(ABSTRACT TRUNCATED AT 250 WORDS)

Afferent Pathways↗