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.
Citations
The central somatosensory conduction time(CCT) was measured by recording the cerebral and spinal evoked potentials following median nerve stimulation in 24 traumatic brain injury patients. The findings of evoked potential study correlated to the functional independence measure(FIM), mini mental status examination(MMSE) and Glasgow outcome scale(GOS).
The CCT of head injured patients was prolonged compared to that of the controls. The CCT with stimulation of the affected side was significantly prolonged compared to that with non- affected side. Abnormal CCT was related to the poor functional status measured by FIM and GOS. There`s no significant difference between groups of absent evoked potential and prolonged CCT by FIM score.
These results suggest that the CCT correlates with the functional status of head injured patients. Follow up studies are required to evaluate whether the CCT could be a valuable prognostic indicator or not.
For the diagnosis of carpal tunnel syndrome (CTS), a sensory conduction study of median nerve is the most sensitive parameter, by either antidromic or orthodromic recording. Many different sensory recordings have been developed to detect the mild or early cases of carpal tunnel syndrome. A comparison of the median and ulnar sensory responses using the 4th digit either orthodromically or antidromically has been one of the methods. However, a simultaneous comparison of both antidromic and orthodromic methods on the 4th digit has not been documented. For the comparison between the median and the ulnar sensory nerve conduction of the 4th digit recorded antidromically or orthodromically, conduction studies of the median and ulnar sensory nerves were performed using standard methods in normal populations as well as in patients with carpal tunnel syndrome. We studied 31 CTS patients (46 hands) with mean age of 54 years old (range, 25∼70). Also, 51 subjects (102 hands) with mean age of 48 years old were studied as control. The difference of antidromic latencies between the median and the ulnar nerves was less than or equal to 0.4 msec in the control subjects and greater than or equal to 0.5 msec in the patients with carpal tunnel syndrome. The difference of orthodromic latencies was less than or equal to 0.5 msec in the control subjects and greater than or equal to 0.5 msec in the patients with carpal tunnel syndrome. By the antidromic and orthodromic methods, the mean difference between latencies of the median or ulnar nerve was not statistically significant. However the amplitude of median or ulnar nerve was 2 times larger by the antidromic method than by the orthodromic. We concluded that the latency difference of 0.5 msec or greater between the median and ulnar nerve sensory conductions from the 4th digit would be valuable for the diagnosis of CTS. The antidromic methods with larger amplitude may be more technically convenient to determine CTS than the orthodromic methods.
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