|
Abnormality |
Interpretation |
|
Abnormal N9-N13 IPL |
This abnormality suggests a
conduction defect in the large fibre sensory system central to the
brachial plexus and below the lower medulla (or cervicomedullary junction)
on the right/left. This does not definitely indicate that there is a CNS
lesion eg radiculopathy can occur between CNS and brachial plexus. |
|
Absent N13 or low amplitude
(with or without abnormal (N9-N19) |
This abnormality suggests a
conduction defect in the large fibre sensory system central to the
brachial plexus and at or below the lower medulla (or cervicomedulllary
junction) following left/right limb stimulation. The absence of the
medullary potential renders it impossible to determine the state of tract
conduction above the lower medulla. |
|
Abnormal N13-N19 |
This abnormality suggests a
conduction defect in the large fibre sensory system above the lower
medulla and below the thalamus on the right/left (contralateral to side of
stimulation). |
|
Normal N13, absent N19-N22 |
This abnormality suggests a
conduction defect in the large fibre sensory system above the lower
medulla on the right/left (contralateral to side of stimulation). If the
lesion is recent, that is, within a few days, and if the disease process
is supratentorial, the absence of N19 suggests that the thalamus is
involved, with new centrum semiovale (white matter) or purely cortical
lesions only P22 is lost initially. |
|
Both N9-N13 & N13-N19 IPL are
abnormal |
This abnormality suggests
conduction defects in the large fibre sensory system both below and above
the medulla (but caudal to the thalamus) following right/left stimulation. |
|
Absent N9 |
If the absolute latencies for
N13 & N19 are normal, then the test can be interpreted as normal.
If the absolute latencies are
abnormal, then the test cannot be interpreted as normal but the
interpretation must reflect the fact that the latency delay could be due
to slowing in the peripheral nerve. |
