Behcet's syndrome with neurological manifestations in two sisters.

Hyperkalaemic periodic paralysis without myotonic features is uncommon (Layzer et al., 1967).However, though the cases described by McArdle (1962) all showed some form of myotonia at some time, in a proportion of the cases myotonia was commonly absent.In our patient a characteristic feature of the attack was his difficulty in moving his eyes.This observa- tion has already been made by Gamstorp (1956).Commonly there is a rise in serum potassium during attacks, though some patients have severe weakness when the level is no higher than 4 mEq/l., whereas in normal people a level of 8 mEq/l. is necessary before weakness develops (Walton, 1966).The serum potassium levels obtained during attacks in this case were on the whole higher than those usually recorded.We checked with control specimens submitted for electrolyte estimation at the same time as blood from the patient, and the results obtained were normal.His potassium levels in between attacks were always within normal limits.Attacks of hyperkalaemic periodic paralysis usually start in infancy and early childhood (McArdle, 1962 ; van't Hoff, 1962), though in one recorded case the initial attack occurred at the age of 20 (Layzer et al., 1967).The attacks in our patient started at a much later age than those reported.Most of the cases described in the literature have a familial history, but sporadic cases, though rare, have been reported.Investigation into a possible familial tendency has been negative in the above case.The patient's father died at the age of 83 from broncho- pneumonia, and his mother died from myocardial infarction at the age of 68.Four of his siblings are abroad but are reported to be well.The remaining five were investigated, with negative results, though his 37-year-old sister had a serum potassium level of 6.2 mEq/l.on one occasion.She was completely symptom-free.It is still possible that she may develop the condition at a later age.