Kozhevnikov–Rasmussen Syndrome and the New Proposal on Classification

To the Editor: The new Classification Scheme of the International League Against Epilepsy (ILAE) (1) makes a historical error by adopting a single eponymic nomenclature “Rasmussen syndrome” in replacement of “Kozhevnikov type 2 syndrome” (current English spelling for the name), officially recognized by the ILAE from 1985 as follows (2): Two types of Kozhevnikov's syndrome are now recognized, but only one of these two types is included among the epileptic syndromes of childhood, because the other one is not specifically related to this age. The childhood disorder, suspected to be of viral etiology, has onset between 2 and 10 years (peak, 6 years) with seizures that are motor partial seizures, but are often associated with other types. However, after a symposium in the Montreal Neurological Institute (June 1988) (3), the name Rasmussen syndrome was introduced in the 1989 ILAE classification (4) as a sharing synonym with “Kozhevnikov type 2 syndrome,” not a substitute for this (4): Two types of Kozhenikov's syndrome are recognized, one of which is also known as Rasmussen's syndrome and is included among the epileptic syndromes of childhood noted under symptomatic seizures. Kozhevnikov (5) superbly described a seizure/status “epilepsia corticalis sive partialis continua” (epilepsia partialis continua) that he attributed to a syndrome of “chronic encephalitis”(5): 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, and proposing the presence of chronic encephalitis. The recent ILAE proposal to eliminate Kozhevnikov from his syndrome of chronic encephalitis is mainly due to a major misconception that Kozhevnikov described Russian spring/summer tick-borne encephalitis. This originates from Andermann (3), who stated, “Epilepsia partialis continua was first described by Kozhevnikov and is still known as Kozhevnikov's epilepsy in francophone countries. Omorokov then showed that it was due to spring/summer encephalitis.” These are erroneous: Kozhevnikov syndrome (type 1 and type 2) was already recognised in the International Classification of the ILAE Commission (2,4). It was well used around the world, including in the American literature, from the beginning of the previous century. For example, in 1924, Wilson and Winkelman (Arch Neurol Psychiatry 1924;11:530–542) of Philadelphia extensively cited Kozhevnikov and described three cases with neuropathologic confirmation of encephalitis. No one ever showed that Kozhevnikov's four patients had tick-borne encephalitis, a disease that was described in 1937, 38 years after his death. Furthermore, only one of his four cases had acute illness: “in all cases the illness developed little by little”(5). The seizure/status “epilepsia partialis continua of Kozhevnikov”(1) (or Kozhevnikov type 1 syndrome) (2,4) is a symptom of many heterogeneous disorders affecting children and adults. What Omorokov (3) found is that many of his cases with epilepsia partialis continua (the seizure) in Siberia (Kozhevnikov was practising in Moscow) had acute encephalitis, and a few had cysticercosis (see translation of the original report by Omorokov) (3). Despite all these, the only reference to Kozhevnikov in the relevant official chapter of the ILAE Task Force (http://www.epilepsy.org) is as follows: “Russian spring-summer tick-borne encephalitis, described by Kozhevnikov (Kozhevnikov, 1991).” Kozhevnikov–Rasmussen syndrome is the only proper nomenclature to honour both these great men who independently described this epileptic syndrome of chronic encephalitis, half a century apart.

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