Epilepsy & Seizures
Benign adult familial myoclonic epilepsy
Apr. 25, 2022
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Ever since described by Hughlings Jackson in the nineteenth century, these focal seizures with a Jacksonian march mimicking the homonucular motor and sensory representation of the brain continue to demonstrate the importance of localization in epilepsy. These seizures remain challenging seizures that are difficult to treat medically and provide surgical challenges due to involvement of eloquent cortex.
Historical note. Since the time of Hippocrates, focal motor seizures have been a clinically recognized phenomenon. Hippocrates astutely understood that seizures arose contralateral to the diseased hemisphere. However, predating the Greeks, the Sakkiku, a medical textbook written in Assyrian Babylonia around 1000 BCE, provides accounts concerning focal motor seizures (84).
Louis François Bravais described a form of focal motor epilepsy in his doctoral thesis published in 1827, roughly 40 years before Jackson’s descriptions. He gave this disease, in which there were only hemibody convulsions, the name l’epilepsie hémiplégique, derived from the Greek hemiplegia, literally meaning “I strike by half” (57; 17). He described 5 different entities of l’epilepsie hémiplégique, which are as follows: (1) those beginning in the face or tongue, (2) those beginning in the upper limbs, (3) those beginning in the lower limbs, (4) those beginning in the abdomen, and (5) those beginning in the course of a peripheral nerve (24). His thesis provided a detailed description of l’epilepsie hémiplégique beginning in the face or tongue. He recognized that the convulsions retreated in the reverse order in which they appeared. Bravais was also aware of a unilateral transient paralysis following an attack and described prodromata of the somatosensory variety.
John Hughlings Jackson furthered our understanding by ascribing the clonic activity to aberrant electrical discharges in the contralateral motor cortex (76). He observed that the face was more commonly involved than the leg and impairment of consciousness did not occur in seizures affecting only 1 side of the body prior to spread to contralateral extremities.
Jackson reported a series of 8 patients in a lecture in 1870 titled “A Study of Convulsions.” Therewithin, he relayed the following:
A married woman, 43 years of age…consulted me at London hospital on December 13, 1864….Exactly one week before at 9 or 10 a.m., her right forefinger and thumb began to work, and the working continued up to the elbow, and then all the fingers worked. (She imitated the movements by alternately shutting and opening the hand.) There was no attendant sensation…She had had three attacks, and after each the hand felt “heavy and dead,” and for some time (she) could not use it well. (76).
His understanding of this disease was augmented by emerging knowledge of pathology, which was not readily available in Bravais’ time. With information derived from necropsy, Jackson was able to deduce that the motor activity was a cortical function, debunking the prevailing belief that epilepsy was a disease originating in the brainstem. In fact, Jackson published “Localized Convulsions from Tumor of the Brain” with Jacksonian seizures (60).
Nomenclature. It was Charcot who coined the term Jacksonian epilepsy, using it to denote seizures with a march of symptoms (21; 20). He was aware of the neglect Bravais’ work had received; hence, “Bravais-Jacksonian seizures” is another eponymous term used to describe the same phenomenon.
When the condition becomes persistent, it is deemed epilepsia partialis continua, a term coined by Kozhevnikov, who remarked:
In recent years I happened to observe several cases of cortical epilepsy…that it may be called epilepsia corticalis sive partialis continua, in that here the convulsive manifestations were continuous….The question of the nature of the disease process is much more difficult…in all cases the illness developed little by little and once it had developed persisted for a very long time, so that we can postulate only chronic processes here….Thus, of the chronic processes, encephalitis with transition to secondary hardening of the brain, or sclerosis cerebri, is almost the only possibility….Thus, not knowing precisely what we are dealing with, [I propose] the presence of a chronic encephalitis (50; 36).
The classification for the different types of epilepsies has undergone several revisions in the 20th century. Jacksonian seizures were categorized under the term “simple partial seizures with motor signs” by the ILAE in 1981 (06). In the 1989 classification, the term Jacksonian seizures was still utilized. In later classifications, these seizures are considered “focal clonic seizures (without spread)” and “Jacksonian march seizures (with local spread)” (07; 25; 26). They are also referred to as “focal motor seizures with elementary clonic motor signs” (25; 26), “clonic seizures,” “simple motor seizures,” or “somatomotor seizures” (56). If the entire hemibody is involved, then they are termed “hemiclonic seizures” (25). If the focal clonic activity persists for a prolonged time, the term epilepsia partialis continua is applied (26). The ILAE classification suggested the term “focal seizures without impairment of consciousness with observable motor components” (13; 65). The ILAE defines Jacksonian march as a “traditional term indicating spread of clonic movements through contiguous body parts unilaterally.” Therefore, one must recognize that the term Jacksonian seizure, which is synonymous with focal motor seizures in clinical parlance, is indeed not synonymous with Jackonsian march. In the proposed ILAE 2016 operational classification of seizures, the terminology used is “focal aware motor (Jacksonian)” (33).
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