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152. The vestibular electrical evoked potential: Technique description of electrical stimulation of human vestibular pathways with recording of scalp responses in control subjects and patients with vestibular dysfunction
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Society Proceedings / Clinical Neurophysiology 123 (2012) e17–e68
Objectives: To compare the sensitivity of the quantitative MUP analysis and the visual qualitative assessment in myopathy. Methods: Subjects consisted of 10 patients with myopathy (7 inclusion body myositis [IBM], 1 suspected IBM, and 2 polymyositis). The flexor digitorum profundus (FDP) muscle was examined in 7 patients and the biceps brachii (BB) muscle was examined in 10. The amplitude, area, duration, area/amplitude, and size index (SI) were evaluated among MUP parameters. Abnormality was judged using the mean parameter values and the outlier evaluation. Control data was collected from 10 age-matched volunteers for each muscle. Results: In the FDP, all 7 patients were judged to have abnormally low amplitude and thin MUPs by visual assessment, whereas abnormal quantitative results were obtained in 7, 7, 3, 4, and 7 patients using mean value and 6, 7, 2, 6, 6 patients using outlier methods for amplitude, area, duration, area/amplitude, and SI, respectively. In the BB, a high-amplitude MUP was scored positive in 5/10 patients qualitatively, whereas maximally 3 patients had abnormal above upper outliers using SI. Conclusions: Qualitative analysis generally was more sensitive than quantitative analysis. This may be due to true high sensitivity or pre-examination bias, which needs to be evaluated using blinded experiments.
doi:10.1016/j.clinph.2011.11.232
152. The vestibular electrical evoked potential: Technique description of electrical stimulation of human vestibular pathways with recording of scalp responses in control subjects and patients with vestibular dysfunction—B.E. Smith 1, M.J. Cevette 1, J. Stepanek 1, D. Cocco 1, K. Brookler 1, G. Pradhan 1, D. Zapala 2, M. Ross 1 (1 Scottsdale, AZ, USA, 2 Jacksonville, FL, USA) Introduction: Despite description of vestibular electrical evoked responses in cat and guinea pig with external auditory canal stimulation, a human vestibular electrical evoked potential (VEEP) technique has not to the authors’ knowledge been reported. Objective: To report a new human VEEP technique stimulating vestibular pathways. Methods: Adult control subjects (23 ears) and patients with vestibular dysfunction (5 ears) were studied with transcutaneous electrical stimulation of the mastoid region. Evoked potentials were recorded over the scalp vertex with standard signal averaging techniques. Responses differed significantly in stimulation threshold, morphology, amplitude, and latency from mastoid dermatomal somatosensory evoked potentials (DSEPs), great auricular sensory nerve action potentials (SNAPs), and frontalis compound muscle action potentials (CMAPs). Results: In control subjects, stimulation of the mastoid region yielded Cz-Fz scalp responses of median amplitude of 281 lV (range 79–449; SD 101) and of median latency of 0.24 ms (range 0.20–0.28; SD 0.01). White noise masking did not significantly affect responses. In patients with vestibular dysfunction the VEEP response of median amplitude was 51 lV (range 19–271; SD 104) and of median latency was 0.20 ms (range 0.18–0.28; SD 0.04). Conclusions: (1) A new technique of human VEEP testing produced reproducible and robust responses in neurologically normal adult control subjects, (2) the VEEP response appears to be lower in amplitude in individuals with vestibular dysfunction, and (3) future studies are needed to explore the utility of the VEEP in disorders affecting the vestibular pathways.
doi:10.1016/j.clinph.2011.11.233
153. Neurophysiological assessment of Wartenberg’s and Trömner signs—A. Recchia (Sao Paulo, Brazil) Introduction: Trömner sign (TS) is considered a pathologic variation of Wartenberg’s sign (WS). TS is a corticalspinal tract sign that can indicate the presence of a lesion in the corticospinal system; however, the lack of an objective quantitative measurement makes it questionable. Objectives: To describe an electrophysiological method to assess WS and TS, and to quantify and establish differences between them in control subjects and patients with lesions of the corticospinal system (CS). Methods: The patient group (PG) consisted of 35 patients with a compromise of the corticospinal system (process in the motor cortex itself, projection fibers, or along the descending tracts). The control group (CG) consisted of 50 healthy adults with no signs of neurological disease. An electronic reflex hammer was used to obtain the reflex responses (RRs) recorded by surface electrodes. Results: RRs could be elicited in all subjects. The mean latency was 19.5 ± 1.8 ms in the CG and 18.5 ± 1.5 ms in the PG. The CG had responses with small mean amplitudes (0.5 ± 0.18 mV) and the PG had markedly hyperactive responses with high mean amplitudes (2.3 ± 1.2 mV). Latencies presented similar values, however a great discrepancy was observed when comparing amplitudes in both groups. Conclusion: Patients with CS lesions had an increased excitability on the lower motor neuron, making it possible to understand the high mean amplitudes found it in this group. RRs could be quantified, allowing a differentiation to be made between groups. These responses proved to be reliable and highly sensitive to predicting the presence of an upper motor neuron lesion. doi:10.1016/j.clinph.2011.11.234
154. Neurophysiological significance of the Trömner sign on the evaluation of cervical spinal cord compression—A. Recchia (Sao Paulo, Brazil) Introduction: Some studies have attempted to determine the sensitivity of some pyramidal signs to predict cervical spinal cord compressions. However, they were based on clinical observations, which makes them very difficult to identify and quantify. Objectives: To evaluate the usefulness of the Trömner sign (TS) obtained by neurophysiological techniques and to establish a correlation between TS and severity of spinal cord compression. Methods: Twenty-one patients with cervical spinal cord dysfunction with or without cervical nerve root injury were evaluated. All patients had some degree of spinal cord and/or radicular compression on magnetic resonance imaging studies. Spinal cord was considered to be compressed when there was a flattening of the cord in its anteroposterior diameter and the cerebrospinal fluid within the subarachnoid space was obliterated at this level. An electronic reflex hammer was used to obtain TS and the responses were recorded by surface electrodes. Results: Fourteen patients presented with an associated radicular compression on needle examination. The remaining showed no abnormalities on needle examination. It was possible to elicit TS in all patients and the mean latency was 18.2 ± 1.4 ms, with high mean amplitudes of 2.3 ± 1.2 mV. A direct correlation between amplitudes and the degree of spinal cord compression could be established. Conclusion: Corticospinal tract responses like TS are not constant, difficult to elicit, and, consequently, less significant when based on clinical observations. Using neurophysiological techniques it was possible to assess, identify, and quantify those responses,
Society Proceedings / Clinical Neurophysiology 123 (2012) e17–e68
Objectives: To compare the sensitivity of the quantitative MUP analysis and the visual qualitative assessment in myopathy. Methods: Subjects consisted of 10 patients with myopathy (7 inclusion body myositis [IBM], 1 suspected IBM, and 2 polymyositis). The flexor digitorum profundus (FDP) muscle was examined in 7 patients and the biceps brachii (BB) muscle was examined in 10. The amplitude, area, duration, area/amplitude, and size index (SI) were evaluated among MUP parameters. Abnormality was judged using the mean parameter values and the outlier evaluation. Control data was collected from 10 age-matched volunteers for each muscle. Results: In the FDP, all 7 patients were judged to have abnormally low amplitude and thin MUPs by visual assessment, whereas abnormal quantitative results were obtained in 7, 7, 3, 4, and 7 patients using mean value and 6, 7, 2, 6, 6 patients using outlier methods for amplitude, area, duration, area/amplitude, and SI, respectively. In the BB, a high-amplitude MUP was scored positive in 5/10 patients qualitatively, whereas maximally 3 patients had abnormal above upper outliers using SI. Conclusions: Qualitative analysis generally was more sensitive than quantitative analysis. This may be due to true high sensitivity or pre-examination bias, which needs to be evaluated using blinded experiments.
doi:10.1016/j.clinph.2011.11.232
152. The vestibular electrical evoked potential: Technique description of electrical stimulation of human vestibular pathways with recording of scalp responses in control subjects and patients with vestibular dysfunction—B.E. Smith 1, M.J. Cevette 1, J. Stepanek 1, D. Cocco 1, K. Brookler 1, G. Pradhan 1, D. Zapala 2, M. Ross 1 (1 Scottsdale, AZ, USA, 2 Jacksonville, FL, USA) Introduction: Despite description of vestibular electrical evoked responses in cat and guinea pig with external auditory canal stimulation, a human vestibular electrical evoked potential (VEEP) technique has not to the authors’ knowledge been reported. Objective: To report a new human VEEP technique stimulating vestibular pathways. Methods: Adult control subjects (23 ears) and patients with vestibular dysfunction (5 ears) were studied with transcutaneous electrical stimulation of the mastoid region. Evoked potentials were recorded over the scalp vertex with standard signal averaging techniques. Responses differed significantly in stimulation threshold, morphology, amplitude, and latency from mastoid dermatomal somatosensory evoked potentials (DSEPs), great auricular sensory nerve action potentials (SNAPs), and frontalis compound muscle action potentials (CMAPs). Results: In control subjects, stimulation of the mastoid region yielded Cz-Fz scalp responses of median amplitude of 281 lV (range 79–449; SD 101) and of median latency of 0.24 ms (range 0.20–0.28; SD 0.01). White noise masking did not significantly affect responses. In patients with vestibular dysfunction the VEEP response of median amplitude was 51 lV (range 19–271; SD 104) and of median latency was 0.20 ms (range 0.18–0.28; SD 0.04). Conclusions: (1) A new technique of human VEEP testing produced reproducible and robust responses in neurologically normal adult control subjects, (2) the VEEP response appears to be lower in amplitude in individuals with vestibular dysfunction, and (3) future studies are needed to explore the utility of the VEEP in disorders affecting the vestibular pathways.
doi:10.1016/j.clinph.2011.11.233
153. Neurophysiological assessment of Wartenberg’s and Trömner signs—A. Recchia (Sao Paulo, Brazil) Introduction: Trömner sign (TS) is considered a pathologic variation of Wartenberg’s sign (WS). TS is a corticalspinal tract sign that can indicate the presence of a lesion in the corticospinal system; however, the lack of an objective quantitative measurement makes it questionable. Objectives: To describe an electrophysiological method to assess WS and TS, and to quantify and establish differences between them in control subjects and patients with lesions of the corticospinal system (CS). Methods: The patient group (PG) consisted of 35 patients with a compromise of the corticospinal system (process in the motor cortex itself, projection fibers, or along the descending tracts). The control group (CG) consisted of 50 healthy adults with no signs of neurological disease. An electronic reflex hammer was used to obtain the reflex responses (RRs) recorded by surface electrodes. Results: RRs could be elicited in all subjects. The mean latency was 19.5 ± 1.8 ms in the CG and 18.5 ± 1.5 ms in the PG. The CG had responses with small mean amplitudes (0.5 ± 0.18 mV) and the PG had markedly hyperactive responses with high mean amplitudes (2.3 ± 1.2 mV). Latencies presented similar values, however a great discrepancy was observed when comparing amplitudes in both groups. Conclusion: Patients with CS lesions had an increased excitability on the lower motor neuron, making it possible to understand the high mean amplitudes found it in this group. RRs could be quantified, allowing a differentiation to be made between groups. These responses proved to be reliable and highly sensitive to predicting the presence of an upper motor neuron lesion. doi:10.1016/j.clinph.2011.11.234
154. Neurophysiological significance of the Trömner sign on the evaluation of cervical spinal cord compression—A. Recchia (Sao Paulo, Brazil) Introduction: Some studies have attempted to determine the sensitivity of some pyramidal signs to predict cervical spinal cord compressions. However, they were based on clinical observations, which makes them very difficult to identify and quantify. Objectives: To evaluate the usefulness of the Trömner sign (TS) obtained by neurophysiological techniques and to establish a correlation between TS and severity of spinal cord compression. Methods: Twenty-one patients with cervical spinal cord dysfunction with or without cervical nerve root injury were evaluated. All patients had some degree of spinal cord and/or radicular compression on magnetic resonance imaging studies. Spinal cord was considered to be compressed when there was a flattening of the cord in its anteroposterior diameter and the cerebrospinal fluid within the subarachnoid space was obliterated at this level. An electronic reflex hammer was used to obtain TS and the responses were recorded by surface electrodes. Results: Fourteen patients presented with an associated radicular compression on needle examination. The remaining showed no abnormalities on needle examination. It was possible to elicit TS in all patients and the mean latency was 18.2 ± 1.4 ms, with high mean amplitudes of 2.3 ± 1.2 mV. A direct correlation between amplitudes and the degree of spinal cord compression could be established. Conclusion: Corticospinal tract responses like TS are not constant, difficult to elicit, and, consequently, less significant when based on clinical observations. Using neurophysiological techniques it was possible to assess, identify, and quantify those responses,