Lithium carbonate in hypokalaemic periodic paralysis--therapeutic trial with negative result

Differential diagnosis of periodic paralysis aided by in vitro myography

In vitro twitch tests were performed on excised muscle bundles from 30 periodic paralysis (PP) patients in an attempt to verify the somatic origin of PP, and to differentiate between the hypokalemic (HypoPP) and the hyperkalemic forms (HyperPP). Seventeen PP patients with a definite diagnosis of familial HypoPP, familial HyperPP (subsequently confirmed by SCN4A mutations), or thyrotoxic PP entered the study, as well as 13 patients with a history of attacks of weakness but with negative clinical provocation tests and therefore ambiguous diagnosis; 15 normal subjects served as controls. In contrast to control, bundles from patients with clear diagnosis went into sustained paralysis on exposure to Cl-free solution. Exposure to K+ channel activators induced a large increase in force. Specifically for HypoPP muscle, low extracellular [K+] decreased twitch force which was further reduced by addition of insulin or adrenaline, whereas HyperPP bundles responded with an irreversible decrease in twitch force when extracellular [K+] was elevated. Out of the 13 patients with unclear diagnosis, the in vitro studies made it possible to classify 10 as HypoPP and one as HypePP (later confirmed by a M1592V mutation). In the remaining two patients who claimed to suffer from paralytic attacks, all in vitro tests were normal, questioning the occurrence of dyskalemic PP. The results demonstrate that in vitro tests can be used to ensure the proper diagnosis to a high percentage when clinical provocative tests have failed.

Familial hypokalaemic periodic paralysis: prevention of paralytic attacks with lithium gluconate

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A review of clinical trials of lithium in neurology

Lithium has been put to clinical trials in no less than fifteen neurological disorders. They are Huntington's chorea, tardive dyskinesia, spasmodic torticollis, Tourette's syndrome, L-dopa induced hyperkinesia and the "on-off" phenomenon in parkinsonism, organic brain disorders secondary to brain-injury, drug induced delusional disorders, migraine and cluster headache, periodic hypersomnolence, epilepsy, meniere's disease and periodic hypokalemic paralysis. This paper gives a brief summary of the clinical trials with lithium salts reported in the literature. There are encouraging results on the use of lithium in cluster headaches, cyclic form of migraine and hypomanic mood disorders due to organic brain disorders. The trials with lithium and amitriptyline in tardive dyskinesia needs independent confirmation. The effect of lithium on seizure disorders needs to be addressed too.