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To identify which combination of motor evoked potentials (MEPs) and somatosensory evoked potentials (SEPs) is most reliable for postoperative motor deterioration during spinal cord tumor surgery, according to anatomical and pathologic type.
MEPs and SEPs were monitored in patients who underwent spinal cord tumor surgery between November 2012 and August 2016. Muscle strength was examined in all patients before surgery, within 48 hours postoperatively and 4 weeks later. We analyzed sensitivity, specificity, positive and negative predictive values of each significant change in SEPs and MEPs.
The overall sensitivity and specificity of SEPs or MEPs were 100% and 61.3%, respectively. The intraoperative MEP monitoring alone showed both higher sensitivity (67.9%) and specificity (83.2%) than SEP monitoring alone for postoperative motor deterioration. Two patients with persistent motor deterioration had significant changes only in SEPs. There are no significant differences in reliabilities between anatomical types, except with hemangioma, where SEPs were more specific than MEPs for postoperative motor deterioration. Both overall positive and negative predictive values of MEPs were higher than the predictive values of SEPs. However, the positive predictive value was higher by the dual monitoring of MEPs and SEPs, compared to MEPs alone.
For spinal cord tumor surgery, combined MEP and SEP monitoring showed the highest sensitivity for the postoperative motor deterioration. Although MEPs are more specific than SEPs in most types of spinal cord tumor surgery, SEPs should still be monitored, especially in hemangioma surgery.
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To evaluate whether the combination of muscle motor evoked potentials (mMEPs) and somatosensory evoked potentials (SEPs) measured during spinal surgery can predict immediate and permanent postoperative motor deficits.
mMEP and SEP was monitored in patients undergoing spinal surgery between November 2012 and July 2014. mMEPs were elicited by a train of transcranial electrical stimulation over the motor cortex and recorded from the upper/lower limbs. SEPs were recorded by stimulating the tibial and median nerves.
Combined mMEP/SEP recording was successfully achieved in 190 operations. In 117 of these, mMEPs and SEPs were stable and 73 showed significant changes. In 20 cases, motor deficits in the first 48 postoperative hours were observed and 6 patients manifested permanent neurological deficits. The two potentials were monitored in a number of spinal surgeries. For surgery on spinal deformities, the sensitivity and specificity of combined mMEP/SEP monitoring were 100% and 92.4%, respectively. In the case of spinal cord tumor surgeries, sensitivity was only 50% but SEP changes were observed preceding permanent motor deficits in some cases.
Intraoperative monitoring is a useful tool in spinal surgery. For spinal deformity surgery, combined mMEP/SEP monitoring showed high sensitivity and specificity; in spinal tumor surgery, only SEP changes predicted permanent motor deficits. Therefore, mMEP, SEP, and joint monitoring may all be appropriate and beneficial for the intraoperative monitoring of spinal surgery.
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To establish a supraorbital nerve sensory conduction recording method and assess its usefulness.
Thirty-one healthy subjects without a history of trauma or neurological disease were recruited. For the orthodromic procedure, the recording electrode was attached immediately superior to the supraorbital notch. The stimulation electrode was placed on points along the hairline which evoked the largest sensory nerve action potentials (SNAPs). The antidromic sensory response was recorded after switching the recording and stimulating electrodes. The measured parameters were onset latency, peak latency, and baseline to peak amplitude of the SNAPs. The electrophysiological parameters of the bilateral supraorbital nerves were compared. We also recruited two patients who had sensory deficits on one side of their foreheads because of laceration injuries.
The parameters of orthodromically recorded SNAPs were as follows: onset latency 1.21±0.22 ms (range, 0.9–1.6 ms), peak latency 1.54±0.23 ms (range, 1.2–2.2 ms), and baseline to peak amplitude 4.16±1.92 µV (range, 1.4–10 µV). Those of antidromically recorded SNAPs were onset latency 1.31±0.27 ms (range, 0.8–1.7 ms), peak latency 1.62±0.29 ms (range, 1.3–2.2 ms), and baseline to peak amplitude 4.00±1.89 µV (range, 1.5–9.0 µV). There was no statistical difference in onset latency, peak latency, or baseline to peak amplitude between the responses obtained using the orthodromic and antidromic methods, and the parameters also revealed no statistical difference between the supraorbital nerves on both sides.
We have successfully recorded supraorbital SNAPs. This conduction technique could be quite useful in evaluating patients with supraorbital nerve lesions.
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Although spinal cord injury without radiographic abnormality (SCIWORA) literally refers to the specific type of spinal cord injury, however, some extents of spinal cord injuries can be detected by magnetic resonance imaging (MRI) in most of cases. We introduce an atypical case of spinal cord injury without radiologic abnormality. A 42-year-old male tetraplegic patient underwent MRI and computed tomography, and no specific lesions were found in any segments of the spinal cord. Moreover, the tetraplegic patient showed normal urodynamic function despite severe paralysis and absent somatosensory evoked potentials from the lower limbs.
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Acute transverse myelitis (ATM) is an upper motor neuron disease of the spinal cord, and concomitant association of peripheral polyneuropathy, particularly the axonal type, is rarely reported in children. Our cases presented with ATM complicated with axonal type polyneuropathy. Axonal type polyneuropathy may be caused by acute motor-sensory axonal neuropathy (AMSAN) or critical illness polyneuropathy and myopathy (CIPNM). These cases emphasize the need for nerve and muscle biopsies to make the differential diagnosis between AMSAN and CIPNM in patients with ATM complicated with axonal polyneuropathy.
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To evaluate whether an initial complete impairment of spinal cord injury (SCI) contributes to the functional outcome prediction, we analyzed the relationship between the degree of complete impairment according to the American Spinal Injury Association impairment scale (AIS), the posterior tibial nerve somatosensory evoked potential (PTSEP) and the changes of functional indices.
Sixty subjects with SCI were studied who received rehabilitative management for over 2 months. The degree of completeness on basis of the initial AIS and PTSEP were evaluated at the beginning of rehabilitation. Following treatment, several functional indices, such as walking index for spinal cord injury version II (WISCI II), spinal cord independence measure version III (SCIM III), Berg Balance Scale (BBS), and Modified Barthel Index (MBI), were evaluated until the index score reached a plateau value.
The recovery efficiency of WISCI and BBS revealed a statistically significant difference between complete and incomplete impairments of initial AIS and PTSEP. The SCIM and MBI based analysis did not reveal any significant differences in terms of the degree of AIS and PTSEP completeness.
AIS and PTSEP were highly effective to evaluate the prognosis in post-acute phase SCI patients. BBS and WISCI might be better parameters than other functional indices for activities of daily living to predict the recovery of the walking ability in post-acute SCI.
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To investigate the predictive index of functional recovery after primary pontine hemorrhage (PPH) using the combined motor evoked potential (MEP) and somatosensory evoked potential (SEP) in comparison to the hematoma volume and transverse diameter measured with computerized tomography.
Patients (n=14) with PPH were divided into good- and poor-outcome groups according to the modified Rankin Score (mRS). We evaluated clinical manifestations, radiological characteristics, and the combined MEP and SEP responses. The summed MEP and SEP (EP sum) was compared to the hematoma volume and transverse diameter predictive index of global disability, gait ability, and trunk stability in sitting posture.
All measures of functional status and radiological parameters of the good-outcome group were significantly better than those of the poor-outcome group. The EP sum showed the highest value for the mRS and functional ambulatory category, and transverse diameter showed the highest value for "sitting-unsupported" of Berg Balance Scale.
The combined MEP and SEP is a reliable and useful tool for functional recovery after PPH.
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To investigate the somatosensory findings of pusher syndrome in stroke patients.
Twelve pusher patients and twelve non-pusher patients were enrolled in this study. Inclusion criteria were unilateral stroke, sufficient cognitive abilities to understand and follow instructions, and no visual problem. Patients were evaluated for pusher syndrome using a standardized scale for contraversive pushing. Somatosensory finding was assessed by the Cumulative Somatosensory Impairment Index (CSII) and somatosensory evoked potentials (SEPs) at 1 and 14 weeks after the stroke onset. Data of SEPs with median and tibial nerve stimulation were classified into the normal, abnormal, and no response group.
In the baseline characteristics (sex, lesion character, and side) of both groups, significant differences were not found. The score of CSII decreased in both groups at 14 weeks (p<0.05), but there were no significant differences in the CSII scores between the two groups at 1 and 14 weeks. There were no significant differences in SEPs between the two groups at 1 and 14 weeks after the stroke onset.
It appears that somatosensory input plays a relatively minor role in pusher syndrome. Further study will be required to reveal the mechanism of pusher syndrome.
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To evaluate the prevalence and risk factors of peripheral neuropathy in patients with rheumatoid arthritis (RA) treated with leflunomide (LEF) by quantitative sensory testing (QST).
A total of 94 patients were enrolledin this study, out of which 47 patients received LEF. The other 47 patients received alternative disease-modifying antirheumatic drugs and served as the control group. The demographic characteristics, laboratory findings, concomitant diseases, and medication history were evaluated at the time of QST. The cooling (CDT) and vibratory detection threshold (VDT) as the representative components of QST were measured.
Age, gender, RA duration, ESR, and CRP did not show any significant differences between the two groups. VDT did not demonstrate any significant difference in both groups. However, CDT in LEF group was significantly higher than that of the control group (8.6±2.7 in LEF vs. 5.6±3.8 in control). The proportion of RA patients in the LEF group showing abnormally high CDT was over 2 times greater than that of the control group, but these findings were not statistically significant. Age, RA duration (or LEF medication in LEF group), ESR, and CRP did not show significant correlation with CDT in both groups. VDT significantly correlated with age in both groups.
LEF treatment in patients with RA may lead to abnormal CDT in QST. CDT value was not affected by age, RA duration, disease activity, or LEF duration. It remains to be determined whether QST may be a valuable non-invasive instrument to evaluate the early sensory changes in patients with RA taking LEF.
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To perform nerve conduction studies of the four branches of the superficial peroneal nerves to determine normal values and anatomic variations in Koreans.
Antidromic sensory nerve conduction studies of the four distal branches were performed on 70 healthy subjects (100 feet). We applied electrical stimulation at the midpoint of medial and lateral malleoli for the medial dorsal cutaneous nerve (MDCN), and at the lateral 1/4 point between the medial and lateral malleoli for the 2 branches of the intermediate dorsal cutaneous nerve (IDCN).
Reference values (mean±SD) of the onset/ peak latency (ms)/ sensory action potential amplitude (µV) for the two branches of the MDCN and for the first branch of the IDCN were 2.2±0.3/2.9±0.3/9.2±3.1, 2.2±0.3/2.8±0.3/9.1±3.0 and 2.3±0.4/2.9±0.3/8.5±2.8, respectively. For the second IDCN branch, the reference values were 2.3±0.4/3.0±0.4/7.1±2.6 but anomalous sural innervation was also found. Three types of IDCN innervations to the fourth interdigital web space were detected. In type I, the fourth interdigital webspace was innervated solely by the IDCN, whereas in type II, it was innervated by both the IDCN and distal sural nerve. In type III, it was solely innervated by the distal sural nerve.
The results of this study show the reference values of the distal sensory branches of the superficial peroneal nerve, and provide information on the variant innervations to the fourth interdigital web space.
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Method: Thirty eight complete peripheral nerve injuries, diagnosed by motor and sensory nerve conduction studies (NCS) and needle electromyography (nEMG), were studied. Nerve injuries were grouped into two groups with and without SEP recorded at the time of initial evaluation. Outcome of nerve injuries was graded from 0 to 3 based on the results of NCSs and nEMG, followed up for more than six months. Grade 0 was designated for those with no evidence of recovery, and grade 3 for those with recovery in nEMG and both motor and sensory NCSs.
Results: At the time of initial electrodiagnosis, SEP study showed no response in 25 cases, but SEP could be observed in 13 cases, although they were attenuated or delayed. Recovery of nerve injury was observed in 22 cases, despite the findings compatible with complete injury in initial NCSs and nEMG. The group in which SEPs were recorded showed significantly higher grades of recovery, compared to no re sponse group.
Conclusion: In predicting the prognosis of complete peripheral nerve injuries, SEP study could be useful as a supplementary electrodiagnostic method.
Method: Retrospective chart review was performed in 561 patients. Among 561 stroke patients, 116 subjects were recruited and classified into two groups: patient group, 43 cases with RSD; control group, 73 cases without RSD. Upper extremity function was assessed based on feeding, dressing and personal hygiene scores of the modified Barthel index at the beginning of rehabilitation treatment and at the time of discharge. Causes of stroke and length of stay were recorded. Median nerve-somatosensory evoked
potential studies were performed and assessed.
Results: The incidence of RSD was 7.7% and the time to development of RSD was 62.3±34.1 days after the onset of stroke. There was no significant difference in functional status between two groups at initial and final evaluation. The upper extremity function had improved in both groups although the length of stay was longer in patient group. SSEP abnormalities were more frequent in the patient group.
Conclusion: The presence of well-managed RSD affected neither the functional status nor the functional recovery of upper extremity in stroke patients. (J Korean Acad Rehab Med 2003; 27: 480-484)
Method: The subjects were 57 patients with first stroke. Somatosensory evoked potential study was performed at the time of transfer to the rehabilitation department. Data of somatosensory evoked potential with median and tibial nerve stimulations were obtained and classified as normal (group 1), abnormal (group 2), and no response group (group 3). Modified Barthel index (MBI), motor and sensory functions were evaluated at the time of transfer and discharge.
Results: MBI score was statistically different among the 3 groups based on the findings of median and tibial nerve SSEP at the time of transfer, but not different at the time of discharge. Motor function was statistically different among the 3 groups at the time of transfer and discharge. Sensory function was statistically different among the 3 groups at the time of transfer, but not different at the time of discharge.
Conclusion: Even though SSEP study reflects the functional status of the patients and correlates well with the findings of brain image, it has limitation in predicting outcome of the patients with stroke. (J Korean Acad Rehab Med 2003; 27: 355-360)
Method: The subjects were 10 healthy volunteers. The study was composed of 3 sessions: first session, baseline evaluation; second session, RES with a intensity for proprioceptive stimulation on tibial nerve at the right ankle for 3 different duration of 30 minutes, 1 hour, and 2 hours; third session, repeat of baseline evaluation after RES (post- RES evaluation). The baseline evaluation include somatosensory evoked potential study with stimulation of right tibial nerve and compound muscle action potential (CMAPs) of tibial nerve recorded at abductor hallucis and H reflex. The amplitude of each study were measured and compared between baseline evaluation and post-RES evaluation using Kruscal-Wallis test.
Results: There was no significant change in amplitudes of SSEP, CMAP and H reflex between baseline evaluation and post-RES evaluation of 30 minutes, 1 hour and 2 hours.
Conclusion: This study suggests that chronic repetitive proprioceptive afferent nerve stimulations could not modulate primary somatosensory cortex in healthy subjects. However, we could not rule out the limitations of sensitivity of somatosensory evoked potential study. (J Korean Acad Rehab Med 2003; 27: 224-227)
Method: The subjects were 50 healthy adults (mean age, 45.6 years) without the clinical signs and symptoms of peripheral neuropathy. All subjects underwent electrodiagnostic evaluation of the following sensory nerves in lower limbs: superficial peroneal, sural, proximal sural, lateral dorsal cutaneous branch of sural nerve (LDSN), and medial plantar. Examined late responses included: tibial F-wave, peroneal F-wave, and H-reflex recorded from the soleus muscle.
Results: No response rates of sensory nerve conduction studies such as superficial peroneal, sural, proximal sural, LDSN, and medial plantar nerves were 2%, 0%, 0%, 24%, and 18%, respectively. No response rates of late responses such as tibial F-wave, peroneal F-wave, and H-reflex were 0%, 2%, and 8%, respectively. And no response rates were significantly correlated with age (p＜0.05).
Conclusion: No response rate of sensory and late responses of lower limbs are relevant to age increments, the results should be considered for an early diagnosis of peripheral neuropathy in the lower limbs of old population. (J Korean Acad Rehab Med 2003; 27: 220-223)
Method: The subjects were 65 patients with neurogenic bladder. The causes of neurogenic bladder were consist of seven brain lesions; 39 spinal cord injuries; 15 cauda equina syndromes; and four peripheral polyneuropathies. PSEP and EBCR were done.
Results: Of the patients with hyperreflexic bladder (43.1%), PSEP latency was normal in 21.4%, delayed in 21.4%, and not obtainable in 57.2%. Of the patients with areflexic bladder (56.9%), PSEP latency was normal in 24.3%, delayed in 21.6%, and not obtainable in 54.1%. Of the patients with hyperreflexic bladder, EBCR latency was normal in 82.1%, delayed in 14.3%, and not obtainable in 3.6%. Of the patients with areflexic bladder, EBCR latency was normal in 16.2%, delayed in 37.8%, and not obtainable in 46.0% (p＜0.01).
Conclusion: There was significant correlation between EBCR and type of neurogenic bladder, but not with PSEP. These results seem to be reflected from the neuro-anatomical lesion of the neurogenic bladder. (J Korean Acad Rehab Med 2003; 27: 70-74)
Objective: We measured current perception threshold (CPT) with transcutaneous electrical nerve stimulation (TENS) to prove the selective increment of the threshold of C sensory fiber and to determine onset time and duration of effect for application of TENS.
Method: TENS were applied to fifteen control volunteers for 20 minutes on hand three times per week for 2 weeks duration. The CPT was tested at the distal interphalangeal joint of the second finger with 5 Hz, 250 Hz, and 2,000 Hz in frequency, respectively. The test was repeated immediately and 30 minutes after cessation of TENS. These tests were performed on the first, eighth, and fifteenth day on application of TENS.
Results: The baseline CPT of C fiber was 32.7⁑6.4 102 mA, Aδ fiber 23.2⁑9.4 102 mA, and Aβ fiber 83.9⁑18.1 102 mA. At 30 minutes after cessation of TENS in the fifteenth day, the CPT of C fiber increased markedly and that of Aδ fiber increased a little. The CPT of Aβ fiber didn't increase for 2 weeks.
Conclusion: With application of TENS, the threshold of C and Aδ fibers selectively increased, especially 30 minutes after removal of TENS application. This effect was outstanding after 2 weeks' application. (J Korean Acad Rehab Med 2002; 26: 161-166)
Objective: The purpose of this study is to evaluate the relationship between cognitive function and findings of evoked potential study in chronic renal failure patients.
Method: Thirty chronic renal failure patients with cognitive dysfunction were recruited, whose mini-mental state examination (MMSE) scores were less than 24 points. According to the underlying diseases of chronic renal failure, we categorized thirty patients into diabetic group (11 patients) and non-diabetic group (19 patients), and the control-group was composed of 15 normal volunteers. Somatosensory evoked potential (SEP) on stimulating median and posterior tibial nerves, and cortical and spinal conduction time of the motor pathways were valuated.
Results: In tibial nerve SEP, N22-P38 interpeak latencies (IPL) were 18.1⁑4.2 msec in the patient group and 15.7⁑1.9 msec in the control group, respectively. In MEP, cortico-lumbar central motor conduction times (CMCT) were 19.5⁑2.7 and 16.5⁑3.0 msec, respectively. CMCT were prolonged in patients than controls (p＜0.05). There was significant correlation between serum creatinine concentration and N22-P38 IPL (r=0.64, p＜0.05), but, there were no correlations between the underlying diseases of chronic renal failure, duration of disease, MMSE score and cortico-lumbar CMCT, N22-P38 IPL (p＞0.05).
Conclusion: Evoked potentials will be helpful in evaluating the patients with cognitive dysfunction in chronic renal failure.
This 32 year-old man sustained crush injury and resultant in paraplegia. Lumbar MRI was taken and revealed fracture and dislocation between L2 and L3 vertebrae bodies. On the day of the injury, he underwent a surgical intervention of posterolateral fixation and bone graft from L1 to L4 vertebrae. He was transferred to Rehabilitation Medicine Department of Asan Medical Center where patient was subsequently found to have an unexpected neurologic finding of decreased sensation below T5 dermatome on right and below T6 on left. Accordingly we took a thoracic MRI which showed features consistent with arachnoiditis at thoracic and lumbar cord segment. A dermatomal somatosensory evoked potential study was performed with finding of abnormal somatosensory pathway below mid thoracic dermatome. We reported an unusual case of thoracic arachnoiditis occurred after the surgical fixation of the lumbar vertebral fracture and dislocation.
Objective: The purposes of this study were to evaluate the diagnostic value of dermatomal somatosensory evoked potentials (DSEPs) in the unilevel/unilateral lumbosacral radiculopathies.
Method: The study was performed on 41 patients with herniated lumbosacral disc which was confirmed by magnetic resonance imaging, and the patients with clinical lumbosacral radiculopathies (L5 radiculopathy in 33 cases and S1 radiculopathy in 8 cases). Stimulation sites were over the dorsum of the foot on the distal fifth metatarsal bone for the S1 dermatome and at the interdigital web space between first and second toe for the L5 dermatome. Recordings were made at Cz' and reference to Fz. Conventional nerve conduction study, needle EMG and H-reflex were also examined.
Results: While the needle EMG showed abnormalities in 32 patients (78.0%), the abnormalities of DSEPs were in 13 patients (31.7%): 33.3% for the L5 radiculopathy and 25.0% for the S1 radiculopathy, respectively. Moreover, there was no significant relationship between the abnormal findings of needle EMG and DSEPs (p＞0.05). The H-reflexes were abnormal in 6 of 7 patients (85.7%). And then two of them were found abnormal in S1 DSEPs.
Conclusion: The conventional needle EMG appears to be the more useful electrophysiological technique in the diagnosis of lumbosacral radiculopathies. The ultimate diagnostic value of DSEPs in lumbosacral radiculopathies is doubtful and controversial.
Objective: The purpose of this study was to determine whether quantitative sensory test can be used as a screening test of peripheral polyneuropathy in patients with diabetes mellitus, and to evaluate the severity of peripheral polyneuropathy in patients with diabetes mellitus using quantitative sensory test.
Method: We performed nerve conduction study to right upper and left lower extremity of the patients. Quantitative sensory test was performed using TSA-2001 thermal sensory analyser on right thenar and left foot dorsum in both diabetic and control groups.
Results: 1) The warm sense and heat pain threshold were higher, the cold sense and cold pain threshold were lower in diabetic group than age-matched control group (p＜0.05). 2) The warm sense and heat pain threshold were higher, the cold sense and cold pain threshold were lower in diabetic group than young-aged control group (p＜0.05). 3) As nerve conduction study results were severe, the cold sense threshold in right thenar were decreased (p＜0.05).
Conclusion: Quantitative sensory study in patients with diabetes mellitus are sensitive to identify neuropathic change; thus, they would be used as the screening method of diabetic peripheral polyneuropathy.
Objective: To establish the posterior cutaneous nerve of arm (PCNA) conduction technique and set up the reference values.
Method: A PCNA conduction study was performed in 80 nerves of 40 neurologically healthy adult subjects with a mean age of 38 years (range, 20 to 56). Dantec Counterpoint MK2 machine was used. The recording bar electrodes were placed 10 cm distal to the axillary fold on a line connecting the posterior axillary fold and the olecranon. Supramaximal stimulation was applied to the axilla posterior to the brachial artery. Onset latency, baseline to peak amplitude and negative spike duration of sensory nerve action potentials were obtained. Skin temperature was measured in the posterior arm and maintained at 34oC or above.
Results: Compound sensory action potential for the PCNA was recordable in all the subjects. The results were as follows: onset latency, 1.7⁑0.1 msec; baseline to peak amplitude, 4.6⁑1.4μV; negative spike duration, 1.1⁑0.2 msec.
Conclusion: PCNA response is readily obtainable. This study may help to assess the pain or paresthesia in the posterior aspect of the arm, although more studies are required for clinical application.
Objective: To investigate the association of the muscle contraction with gating of the sensory input at central and peripheral levels according to the intensity of muscle contraction and location of the muscles, somatosensory evoked potentials (SSEPs) studies were evaluated at different levels of isometric contraction in the different muscles.
Method: Median nerve SSEPs were recorded at Erb's point and scalp in the ten healthy adult subjects with isometric contraction of ipsilateral abductor pollicis brevis (APB), ipsilateral abductor digiti minimi (ADM) and contralateral APB. Median nerve SSEPs were recorded in each of these conditions during precontraction, weak contraction, strong contraction and 4 minutes after contraction.
Results: 1) N9 amplitudes of median SSEPs recorded at Erb's point were augumented during weak contraction and these amplitude augumentations were statistically significant in the ipsilateral APB contraction (p＜0.05). 2) N20 amplitudes recorded at scalp were inhibited during strong isometric contraction and these amplitude inhibitions were statistically significant in the ipsilateral APB contraction (p＜0.05). 3) The latencies of N9 and N20 potentials were not significantly changed during isometric contraction.
Conclusion: Therefore peripheral nervous system as well as central nervous system is responsible for gating, so the subject should be asked for the best relaxation possible for higher reliability of SSEPs.
Objective: To investigate the influence of electronic filter setting change on the parameters of motor and sensory nerve conduction studies.
Method: Median motor and sensory nerve conduction studies were performed in 25 neurologically healthy adult subjects with a mean age of 29 years (range, 20∼50). Compound muscle action potentials (CMAPs) and sensory nerve action potentials (SNAPs) were recorded after fixing the low frequency filter cutoff value of 1 Hz, 10 Hz, 100 Hz and 300 Hz and by changing high frequency filter cutoff level from 10 KHz to 0.5 KHz. Onset and peak latency, amplitude of CMAPs and SNAPs were measured and the area of CMAPs were also recorded. Dantec Counterpoint MK2 machine was used. Skin temperature was maintained at 34oC or above.
Results: As the high frequency filter was changed from 10 KHz to 0.5 KHz, the mean amplitude of SNAPs and CMAPs decreased by 33.5%, 3.3%, respectively. Onset and peak latency prolonged significantly below the high frequency filter level of 2 KHz (p＜0.01). When the low frequency filter was varied form 1 Hz to 300 Hz, large differences were seen in amplitude (69.7%) and area (86.5%) of CMAPs and amplitude of SNAPs (36.6%) (p＜0.01), but onset latency was not changed. Peak latency of CMAPs decreased by 20.8%, however, the peak latency of SNAPs reduced slightly (1.4%) (p＞0.01).
Conclusion: Significant alterations in parameters of CMAPs and SNAPs were produced by modification of filter setting. Optimum filter setting is recommended in nerve conduction study and filter parameters must remain constant when determining normal values and when performing serial studies on patients.
Objective: To compare current perception threshold with nerve conduction study, we measured current perception threshold (CPT) in healthy control and patients with carpal tunnel syndrome (CTS).
Method: Twenty control subjects and twenty patients with CTS were included. Latency and amplitude of median and ulnar motor and sensory nerves were measured. The sensory current perception threshold was measured at the distal interphalangeal joint of third and fifth fingers and the palm with electrical current of 5 Hz, 250 Hz, and 2,000 Hz in frequency. We compared the results of the nerve conduction study with the data of the CPT.
Results: We found that measuring of the sensory threshold might detect carpal tunnel syndrome, especially with 2,000 Hz and 250 Hz stimulation and that CPT data correlated to sensory latency and amplitude of the median nerve.
Conclusion: The sensory threshold test might be useful for diagnosis and follow up test in carpal tunnel syndrome.
Objective: To investigate the influence of five different recording electrodes on the various parameters of sensory nerve action potentials (SNAPs).
Method: Median sensory nerve conduction study was performed in 50 normal subjects using different five types of recording electrodes-disc electrode, ring electrode, bar electrode and two kinds of felt-tip bar electrodes (type 1 and 2). The interelectrode distances between active and reference electrodes were set at 4 cm for the disc and ring electrodes. The bar electrode, felt-tip electrodes type 1 and 2 were fixed at interelectrode distances of 3 cm, 3.7 cm and 2.3 cm, respectively. Onset and peak latency, onset to peak amplitude, peak to peak amplitude and duration of negative spike of SNAPs were measured. These parameters were compared using ANOVA test.
Results: Onset and peak latencies of SNAPs recorded from five different electrodes were not different (p＞0.05). Onset to peak and peak to peak amplitudes of SNAPs recorded from felt-tip type 2 electrode were significantly reduced compared to other electrodes (p＜0.05). Onset to peak amplitude of SNAPs was also reduced when the ring electrode was used (p＜0.05). The negative spike durations of SNAPs recorded from felt-tip type 2 and bar electrodes were shorter than other electrodes recording (p＜0.05).
Conclusion: Onset and peak latencies of SNAPs were not affected by the types of electrodes used. Shortening of interelectrode distance may be a main cause of reduction of peak to peak amplitude and negative spike duration of SNAPs.
Objective: To obtain normal data of quantitative sensory test (QST) in Korean adult.
Method: The subjects were 85 normal adults aging from 30 to 69 years old, who had no abnormal sensory and neurologic problem. We performed following three QSTs on dominant side and one verbal questionnaire. 1) Semmes-Weinstein monofilament wire system (0.05 G, 0.2 G, 2 G, 4 G, 10 G, 300 G) for touch sensation, 2) Rydel-Seiffer Tuning Fork for vibration sensation, 3) TSA-2001 Thermal sensory analyser for thermal sensation, 4)University of Texas Subjective Peripheral Neuropathy verbal questionnaire.
Results: 1) Touch perception score measured with Semmes-Weinstein monofilament wire system, declined with age (p＜0.01). 2) Vibration perception score measured with the tuning fork, declined with age in foot (p＜0.01). 3) Warm sense and heat pain threshold measured with TSA-2001 thermal sensory analyser increased with age, and cold sense and cold pain threshold declined with age. 4) Weight showed negative correlation with vibration perception score in man's foot.
Conclusion: Normal data of three sensory test obtained from this study could be used for the early detection of peripheral neuropathy or loss of "protective sensation".
Objective: Intraoperative somatosensory evoked potentials (SEPs) are widely used for the early detections of cerebral ischemia during temporary occlusive procedures of the parent vessels in aneurysm surgery. This study intended to evaluate the usefulness of median nerve SEPs during intracranial aneurysm surgery.
Method: Between September 1995 and June 1997, we monitored 42 aneurysm patients in Uijongbu St. Mary's hospital. Median nerve SEPs were detected on scalp and cervical spine during surgery. We measured latencies, amplitudes of N20 and N13 waveforms and central conduction time (CCT, N20-N13). We analyzed pre- and post-surgical radiologic findings and changes of neurologic signs.
Results: The delayed latencies, CCT, and reduced amplitudes of median nerve SEPs during intraoperative monitoring were closely related to neurological deficits after surgery.
Conclusion: Intraoperative SEPs are useful in preventing clinical neurological injury during surgery of intracranial aneurysm and in predicting which patients will have unfavourable outcomes.
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