Biomedical subjects

Kristin R Black

Publications and source records attributed to Kristin R Black.

4 recordsLinked to original sources

PubMed2006

Cervical nerve root stimulation. Part I: technical aspects and normal data.

OBJECTIVE: Cervical nerve root stimulation (CRS) is a technique of assessing the proximal segments of motor axons destined to upper extremity muscles. Few studies report normal values. The objective was to determine CMAP onset-latencies and CMAP amplitude, area, and duration changes in healthy controls for the abductor pollicis brevis (APB), abductor digiti minimi (ADM), biceps, and riceps muscles. In addition, to determine the tolerability of CRS, as measured by the visual analog scale (VAS). METHODS: We studied 21 healthy volunteers prospectively with CRS using four target muscles (APB, ADM, biceps, and triceps) bilaterally. Collision studies were used in all APB recordings. VAS was obtained in all subjects. RESULTS: Mean CMAP onset-latencies were: APB 14 +/- 1.5 ms; ADM 14.2 +/- 1.5 ms; biceps 5.4 +/- 0.6 ms; triceps 5.4 +/- 1.0 ms. Onset-latency significantly correlated with height for all nerves. The mean change in CMAP amplitude and area (%) between most distal stimulation and CRS was: APB reduction of 15.1 +/- 11.6 and 4.9 +/- 3.6%; ADM reduction of 21.1 +/- 10.7 and 17.2 +/- 8.8; biceps reduction of 10 +/- 11.5 and reduction of 8.7 +/- 6.8; triceps increase of 3.3 +/- 5.2 and 11.0 +/- 9.9% respectively. Mean CMAP duration change between most distal stimulation and CRS was: APB, increase of 20.4 +/- 7.4%; ADM, increase of 14.4 +/- 8.5%; biceps, increase of 13.9 +/- 10.8%; triceps, increase of 7.7 +/- 6.7%. The mean VAS score was 3.8 +/- 1.2, and all subjects completed the study. CONCLUSIONS: The present study establishes normative data and indicates that CRS is a well-tolerated technique. SIGNIFICANCE: The normal values may be used as reference data for the needle CRS technique in the assessment of proximal conduction abnormalities.

Adult↗

PubMed2004

Multifocal motor neuropathy: decrease in conduction blocks and reinnervation with long-term IVIg.

BACKGROUND: Multifocal motor neuropathy with conduction blocks (MMNCB) is an immune-mediated motor neuropathy. Previous long-term IV immunoglobulin (IVIg) treatment studies have documented improvement in muscle strength and functional disability but revealed a concomitant increase in acute axonal degeneration (AD) and conduction block (CB). OBJECTIVE: To determine the long-term effects of IVIg therapy on clinical and neurophysiologic outcome measures in MMNCB patients responsive to IVIg. METHODS: The authors reviewed medical records of 10 patients with MMNCB for outcomes in muscle strength (Medical Research Council score), functional disability (Modified Rankin Disability score), CB, and AD. All patients had received IVIg (2g/kg in 5 days for 3 consecutive months), followed by monthly maintenance therapy. RESULTS: Patients were followed for an average of 7.25 years (range, 3.5 to 12 years). There was significant and sustained improvement in muscle strength and functional disability while on IVIg therapy. Furthermore, the authors found significant improvement in CB, decrease in AD, and evidence of reinnervation by the end of the follow-up period. CONCLUSION: Long-term IV immunoglobulin therapy improves muscle strength and functional disability, decreases the number of conduction blocks and the extent of axonal degeneration, and promotes reinnervation. These findings differ from previous reports of deterioration in neurophysiologic outcome measures. Comparison of the IV immunoglobulin regimen in those reports and this study shows that the authors' patients were treated with significantly higher IV immunoglobulin maintenance doses. These findings have implications for the long-term treatment of patients with multifocal motor neuropathy with conduction blocks.

Action Potentials↗

PubMed2004

Neurophysiologic findings in early acute inflammatory demyelinating polyradiculoneuropathy.

BACKGROUND: Patients with early acute inflammatory demyelinating polyradiculoneuropathy (AIDP) may not meet the current neurophysiologic criteria. OBJECTIVE: To document neurophysiologic findings in early AIDP. METHODS: Clinical and neurophysiologic data from 38 AIDP patients, assessed within 10 days of symptom onset were reviewed. RESULTS: In addition to absent H reflexes and abnormal F-wave responses in the acute stage of AIDP, abnormalities of blink reflexes, upper limb sensory responses abnormalities with spared sural responses, presence of distal CMAP dispersion, and A-waves were frequently observed. Established demyelinating neurophysiologic parameters were infrequently seen. CONCLUSIONS: Abnormalities of H reflexes and F responses were most frequently noted in early AIDP. Additionally, distal temporal dispersion, prolonged or absent blink reflexes, and A-waves were often present in the acute stage of AIDP when classic diagnostic criteria of AIDP were not satisfied. SIGNIFICANCE: Neurophysiologic studies in early AIDP frequently reveal abnormalities that are not specific of primary demyelinating neuropathy.

Adolescent↗

PubMed2002

Transcranial magnetic stimulation of visual area V5 in migraine.

OBJECTIVE: To examine visual cortical excitability in persons with migraine using transcranial magnetic stimulation (TMS) over an extrastriate area of the brain, area V5. BACKGROUND: Previous studies found that persons with migraine have a lower phosphene threshold than healthy control subjects with TMS delivered over the primary visual cortical area V1. The result suggests that the occipital cortex in migraineurs between migraine attacks is hyperexcitable. However, it is not known whether interictal cortical hyperexcitability is also present in areas of the association visual cortex. METHOD: To investigate this, single-pulse TMS was delivered over visual area V5, the motion cortex, to 16 persons with migraine and visual aura, nine migraineurs without visual aura, and 16 healthy control subjects. TMS was delivered at intensities ranging from 30 to 100% of maximum stimulator output or until the participant reported seeing phosphenes (visual illusions characterized by flashes of light). Thresholds to phosphenes were obtained for each participant using a staircase procedure. RESULT: Significantly lower phosphene thresholds for TMS delivered over V5 were found in migraineurs as compared with control subjects. Qualitatively, the migraineurs' experience of phosphenes were more vivid, florid, and sustained compared with that of control subjects. CONCLUSION: Results of this study indicate that hyperexcitability of the visual cortex in migraine goes beyond visual area V1 and demonstrates for the first time a significant difference in threshold for excitability of visual area V5 in persons with migraine.

Adolescent↗