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occasions and without knowledge of previous ratings. Subsequently,<br />
discharge letters and follow-up notes were consulted, covering a period of<br />
up to two years after the investigation.<br />
Electromyographic criteria<br />
Guidelines as to what electromyographic patterns make up a pathological<br />
EHL reflex - representing a Babinski sign - were derived from Chapter<br />
III, which includes findings in 15 patients with a clear Babinski response<br />
and in 40 control subjects:<br />
1. The EHL reflex should coincide with a reflex in the T A. Isolated<br />
potentials in the EHL could result from irritation by the tip of the<br />
recording electrode, especially when the needle is levered by voluntary<br />
or reflex activity of other muscles through which it was inserted.<br />
2. Potentials should be dense enough not to be separately identifiable<br />
('interference pattern'- that is, at 500 msjcm time base). The potentials<br />
can be either continuous or in regular clusters (clonic reflex- of course<br />
not to be confused with clonic tendon jerks (Barre, 1926)).<br />
3. Larger potentials should appear in the middle of the reflex, indicating<br />
recruitment of motoneurones of increasing size, so that, ideally, a<br />
spindle shape is formed. On the other hand it should be kept in mind<br />
that, besides motor unit size, electrode position is another factor<br />
determining spike amplitude.<br />
4. The end of the reflex should be visible: voluntary withdrawal rends to<br />
linger on for a few seconds, and flexor spasms are hardly to be expected<br />
in this group of patients.<br />
5. There should be no concomitant reflex in the FHB.<br />
Starting from these criteria, the EMG patterns of each investigation<br />
were allocated to one of five possible categories. Relevant examples are<br />
shown in figure 10. If the qualifications for a pathological EHL reflex were<br />
partly met, a probable EHL reflex could be rated; this was minimally<br />
defined by the presence of the first two criteria in two out of the six<br />
photographs. When neither of these two pathological ratings was applicable,<br />
the result was considered normal, and was further specified as<br />
definite or probable FHB reflex (cf. criteria 2, 3 and 4 for the EHL) or no<br />
reflex activity at all. Strictly speaking, an absent reflex can be abnormal<br />
when a FHB response is found on the other side (Harris, 1903; Kino,<br />
1927), bur only one side was investigated.<br />
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