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Biomedical subjects

M Grevitt

Publications and source records attributed to M Grevitt.

8 recordsLinked to original sources
PubMed2002

Combined monitoring of motor and somatosensory evoked potentials in orthopaedic spinal surgery.

OBJECTIVES: To demonstrate possible advantages of combined (motor and sensory) versus single modality (either motor or sensory) intra-operative spinal cord monitoring and to investigate risk factors for post-operative neurological sequelae. METHODS: Recordings of lower limb motor evoked potentials (MEPs) to multi-pulse transcranial electrical stimulation (TES), and tibial nerve somatosensory evoked potentials (SEPs), were attempted during 126 operations in 97 patients (79 with spinal deformity and 18 with miscellaneous spinal disorders). RESULTS: Combined motor and sensory monitoring was successfully achieved in 104 of 126 (82%) operations. No response to either modality could be recorded in two patients with Friedreich' s ataxia. In 18 patients monitoring was possible in only one modality: SEPs could not be recorded in two patients and MEPs in 16. Significant intra-operative EP changes occurred in one or both modalities in 16 patients; in association with instrumentation in 10 cases, and with systemic changes in 6. After appropriate remedial measures, SEPs recovered either fully or partially in 8/8 patients and MEPs in only 67% (10/15 patients). New deficits were present post-operatively in 6 of the 16 patients with abnormal intra-operative EPs. Normal MEPs at the end of the operation correctly predicted the absence of new motor deficits in all cases. SEPs either remained unchanged or recovered fully after remedial measures in 3 patients with new post-operative motor deficits. Neurological complications were more frequent in patients with miscellaneous spinal disorders and/or pre-existing neurological deficits. No complications occurred in patients with idiopathic scoliosis. CONCLUSIONS: Combined SEPs and multi-pulse TES-MEPs provide a safe, reliable and sensitive method of monitoring spinal cord function in orthopaedic surgery. This method is superior to single modality techniques, both for increasing the number of patients in whom satisfactory monitoring of spinal cord function can be achieved and, for improving the sensitivity and predictivity of monitoring. Combined SEP/MEP methods may enhance the impact of neuromonitoring on the intra-operative management of the patient and favourably influence neurological outcome.

Action Potentials↗
PubMed2001

A 3D MRI sequence for computer assisted surgery of the lumbar spine.

The aim of this research was to develop a magnetic resonance (MR) sequence capable of producing images suitable for use with computer assisted surgery (CAS) of the lumbar spine. These images needed good tissue contrast between bone and soft tissue to allow for image segmentation and generation of a 3D-surface model of the bone for surface registration. A 3D double echo fast gradient echo sequence was designed. Images were filtered for noise and non-uniformity and combined into a single data set. Registration experiments were carried out to directly compare segmentation of MR and computed tomography (CT) images using a physical model of a spine. These experiments showed the MR data produced adequate surface registration in 90% of the experiments compared to 100% with CT data. The MR images acquired using the sequence and processing described in this article are suitable to be used with CAS of the spine.

Humans↗
PubMed2000

Injury to the spinal cord without radiological abnormality (SCIWORA) in adults.

Injury to the spinal cord without radiological abnormality often occurs in the skeletally immature cervical and thoracic spine. We describe four adult patients with this diagnosis involving the cervical spine with resultant quadriparesis. The relevant literature is reviewed. The implications for initial management of the injury, the role of MRI and the need for a high index of suspicion are highlighted.

Adolescent↗
PubMed1998

Do first impressions count? A comparison of subjective and psychologic assessment of spinal patients.

Psychologic factors may have a major influence on the outcome of treatment for back pain. Psychologic disturbance is manifest as emotional distress and may be associated with inappropriate symptoms and signs. Few outcome studies describe the patient population in terms of their psychologic profile. Anecdotal evidence suggested that the routine use of psychologic screening tests in British spine practice was rare. An audit of the prevalent use of psychologic testing amongst a selected group of British spinal surgeons was conducted. This was followed by a prospective, double blind comparison of subjective evaluations of patients with formal psychologic tests. The principal aim was to determine how accurately treating physicians could identify psychologically distressed patients. A postal questionnaire was sent to all consultant members of the British Orthopaedic Spine Society. Details of their current practice and frequency of use of psychologic tests was obtained. In a subsequent study, 125 consecutive new patients attending a back pain clinic were initially evaluated by questionnaires and classified as either psychologically distressed or non-distressed. These patients were then interviewed and examined by treating physicians, who then allocated them to one of four psychologic categories, using predefined criteria. The two results were compared and sensitivity, specificity and predictive values for the subjective evaluations were calculated. Sixty-three percent of respondents to the postal survey either never or only occasionally used any form of psychologic testing in assessing back pain patients. The follow-up prospective study demonstrated that experienced spinal surgeons achieved only a 26% sensitivity when trying to identify distressed patients. The specificity for identifying non-distressed patients was 96%. The predictive value of a "distressed" evaluation was 69%. The predictive value for non-distressed patients was 77%. Subjective psychologic assessment of back pain patients has a low sensitivity and predictive value for distressed patients. Formal psychologic screening should be routinely included in the clinical decision making process.

Attitude of Health Personnel↗
PubMed1997

The short form-36 health survey questionnaire in spine surgery.

The Short Form-36 (SF-36) health questionnaire has been put forward as a general measure of outcome in health care and has been evaluated in several recent studies in the UK. We report its use in three groups of patients after spinal operations and have compared it with the Oswestry and Low Back Pain disability scales. There was a significant correlation between all variables of the SF-36 and the low-back scores. The mental-health items had the weakest correlation. Our study shows that the SF-36 questionnaire is valid and has internal consistency when applied to these patients.

Adolescent↗
PubMed1993

Bone single-photon emission tomography in recent meniscal tears: an assessment of diagnostic criteria.

Bone single-photon emission tomography (SPET) was performed in 40 patients within 6 months of acute knee injury where internal derangement of the knee was suspected, and the results related to the arthroscopy findings. Scan features with high sensitivity, specificity, and predictive accuracy for a meniscal tear could not be obtained on planar imaging. However, a half-crescent or more of increased tibial plateau activity on transaxial SPET gave a sensitivity of 89%, a specificity of 76%, a positive predictive accuracy of 77% and a negative predictive value of 89%. For longitudinal (bucket handle) tears alone the optimum scan pattern was a full crescent of increased tibial plateau activity with adjacent femoral activity and increased blood pool activity which gave corresponding values of 78%, 94%, 78% and 93%. It is concluded that the inclusion of tibial plateau activity of less than a full crescent and the presence of femoral condyle and blood pool activity in the diagnostic criteria improves the ability of bone SPET to detect meniscal tears. The value of bone SPET in the diagnosis of meniscal tears suggests that it could have a significant role to play in the management of knee injuries.

Adolescent↗