Create successful ePaper yourself
Turn your PDF publications into a flip-book with our unique Google optimized e-Paper software.
RESULTS<br />
Observer consistency<br />
The rating of EMG patterns scarcely varied throughout the five sittings.<br />
Intra-observer variation in the form of a contradiction 'pathological' and<br />
'not pathological' occurred in five of the 60 sets of pictures. In four, only<br />
one of the five readings was at variance with the others. These exceptions<br />
were disregarded when both investigations in each patient were compared<br />
(EMG consistency), as they did not appear in the same pair, so that the<br />
chance of a contradictory outcome was one in ten in these four patients. In<br />
one further set, two readings were opposed to the other three.<br />
Of the remaining 55 sets, 43 had received an identical classification on<br />
the five-point scale on each of the five occasions. In 12, there was some<br />
shift within the same group - that is, FHB reflex, probable FHB reflex or<br />
no reflex on the one side versus EHL reflex or probable EHL reflex on the<br />
other.<br />
EMG consistency<br />
After interpretation, the patient code was broken and the results of the<br />
two investigations for each patient were matched and compared. The<br />
repetition of the EMG examination led to a similar conclusion in 26 of the<br />
30 patients (87% ). Twenty pairs were both interpreted as normal, six both<br />
as pathological. When chance agreement is taken into account, as well as<br />
disagreements within the two main categories of 'pathological' and 'not<br />
pathological', the weighted agreement rate (kappa; Cohen, 1960, 1968)<br />
was 0.61.<br />
Of the four mismatches, two plantar reflexes were rated normal once<br />
and possibly pathological the other time, in one the outcome went from<br />
absent to definitely pathological. These three cases with inconsistent EMG<br />
results included two patients who showed on clinical examination bilateral<br />
but exceptionally fast upgoing toes, with the additional problem that no<br />
adequate cause could be found for this; they will be discussed separately<br />
below. The fourth mismatch was caused by the set mentioned in the<br />
previous section, in which two readings contradicted the other three; the<br />
twin set showed a definite EHL reflex. True variation of the plantar reflex<br />
within one week is of course p()ssible, but was not a factor here.<br />
94
Change language