Biomedical subjects
Publications and source records attributed to T Sand.
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The correlations between clinical signs and BAEP latency, amplitude and dispersion variables were investigated in 98 multiple sclerosis patients. A new dispersion variable, the wave IV-V "shape ratio" (SR IV-V), correlated most strongly with brain-stem signs (i.e., nystagmus). Severely reduced wave IV-V amplitude was frequently found in patients with vertical nystagmus or internuclear ophthalmoplegia, and interpeak latency (IPL) III-V correlated most strongly with cerebellar dysfunction (i.e., ataxia). The results may reflect different localizing ability among the various BAEP variables. The association between ataxia and increased IPL III-V was significantly stronger for BAEP to C clicks than to R clicks. Patients with abnormal BAEPs to one polarity (C or R) but not to the other, had significantly more clinical dysfunction than patients with normal BAEPs to both C and R clicks. Hence, C vs. R discordance may be interpreted to indicate possible brain-stem dysfunction.
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Pupillometric studies were carried out in 9 patients with chronic paroxysmal hemicrania (CPH), in 10 patients with hemicrania continua (HC) and in age- and sex-matched controls (n = 12-17). Studies were carried out in the basal condition and after instillation of 2% tyramine, 1% OH-amphetamine, or 1% phenylephrine. The pupillary response to tyramine in HC was more marked than in controls on a percentage increase basis, but not so much when the increment is calculated in absolute values. In this series, there was no asymmetrical response (relative miosis on the symptomatic side) like in previous case reports. The pupil reaction was less in HC than in CPH after hydroxyamphetamine instillation and without any marked asymmetry. There was no definite evidence of supersensitivity to a directly acting sympathicomimetic agent, phenylephrine. No gross abnormalities as regard the sympathetic function in HC was thus observed. The asymmetry on tyramine testing differed in CPH and HC (most marked in HC). No major emphasis should probably be attached to this finding, since on testing with OH-amphetamine, a similar substance, this finding was not reproduced.
EEG abnormalities in migraine have been reported by a number of authors during the last 50 years. Prevalences vary considerably in the older literature. A number of unspecific rhythms related to drowsiness or hyperventilation have probably been counted as "abnormal", and the reported numbers of definitely abnormal EEG rhythms have been consistently low. In a few controlled and blinded studies, however, slight excess of various EEG rhythms has been found in migraine patients. Similar prevalences of interictal EEG abnormalities have generally been found in patients with classic and common migraine, but the diagnostic classification may not have been precise enough in some studies. During visual aura, either slow waves, depression of background activity amplitude or normal EEG have been reported. The most definitely abnormal EEGs with unilateral or bilateral delta activity have been recorded during attacks of hemiplegic migraine, and during attacks of migraine with disturbed consciousness. The relationship between migraine and epilepsy has still not been adequately clarified. The connection seems to exist in several small entities (e.g. migraine-like headache as an epileptic manifestation, epileptic seizures triggered by epileptic attacks, and possibly in epilepsies with occipital spike waves), but it is seemingly not "fundamental". Newer methods, i.e. EEG frequency analysis and topographic brain mapping, are promising tools in this field. So far, mostly small studies have been published with somewhat inconsistent results. A pattern of increased alpha rhythm variability (and/or asymmetry) in the headache-free phase seems to emerge, however. Significant asymmetry of alpha and theta during headache has been reported in one topographic brain mapping study. Magnetoencephalographic studies of migraine patients have demonstrated slow wave-shifts (similar to those observed in animals with spreading depression). The EEG patterns observed in migraine patients seem to suggest a possible physiological connection between sleep, hyperventilation and migraine. The study of such relationship may shed new light on migraine pathophysiology.
Tyramine pupillometry was performed in 27 cluster headache patients and in 45 healthy controls. Asymmetry variables, i.e. symptomatic(S)-nonsymptomatic(NS) side diameter difference and the ratios (S/NS, log NS/S or S/S+NS) displayed higher sensitivities than variables which express the function of the symptomatic and the nonsymptomatic side pupil separately. Thirty percent of patients had abnormal S-NS values at maximal pupillary dilatation. The statistical properties of different ratio variables are discussed and it is concluded that the transformed ratio (log(NS/S], anisocoria (S-NS) and the anisocoria index (S/S+NS) may be superior to the conventional S/NS ratio.
Twenty-two patients with classic migraine and eleven patients with cervicogenic headaches were questioned about the localization of the initial and late pain during attack. Twenty of the classic migraine patients (91%) felt the initial pain in the forehead and temporal areas, whereas an ocassional, solitary primary involvement of the neck was found in one case (5%). As the attack evolved, there was a co-involvement of more areas. An initial involvement of the forehead and temporal area occurred in only 3 patients (27%) with cervicogenic headache, whereas 8 (73%) felt the initial pain in the neck. Also in the cervicogenic headache patients there was subsequent coinvolvement of more areas as the attack evolved. In the full-blown attack, the pain seemed very similar in the two patient groups. The localization of initial pain may be a useful feature in pattern recognition in headache diagnostics.
The ocular sympathetic function was examined in 79 healthy volunteers (37 males and 42 females) by electronic pupillography. Pupillary diameters were first estimated under standard light conditions prior to drug application, these diameters being termed "basal values". Then, the pupils were stimulated pharmacologically by instillation of various sympathicomimetic drugs: tyramine tests were carried out in 42 individuals (24 females; 18 males), hydroxyamphetamine tests in 38 (22 females and 16 males), and phenylephrine tests in 43 individuals (23 females and 20 males). Generally, only a minor variation in the frequency of asymmetries was observed between sexes as well as between the various age groups, both when calculating the increase in pupillary diameter in millimeters, in per cent, and as the anisocoria index. In agreement with previous investigations, pupil size was found to diminish with age. The use of an age-matched control material is mandatory when comparing pupillographic recordings in patients in various categories, in the ordinary condition, as well as after topical drug administration.
In cluster headache, forehead sweating is frequently pathological and for this reason it is important to know the normal pattern. In the present work, sweating was induced by exercise and pilocarpine in 14 healthy individuals in the age group 24-50 years. A comparison was also made with patterns of heat-induced forehead sweating. No definite left-right asymmetry or medial-lateral preponderance were observed. As expected, the sweat patterns following body heating and exercise were rather similar. However, there was a significant relative increase in lateral forehead sweating with heat-induction as compared to pilocarpine-induction. In comparative intra- or inter-individual studies of forehead sweating, the method of sweat provocation may, therefore, not be indifferent.
A comparison of heat-induced forehead sweating and cutaneous temperature patterns has been carried out in 17 healthy individuals (a total of 54 measurements). Only minor asymmetries in facial sweating and temperature were observed. No significant correlation between sweating and cutaneous temperature was found. The reproducibility of the method was excellent.