Rasmussen syndrome, also known as Rasmussen’s encephalitis, was first reported by Rasmussen in 1958 and has been reported in various countries since then. It is a rare but severe disease with unilateral hemispheric atrophy caused by immune-mediated brain dysfunction, combined with progressive neurological dysfunction and refractory epilepsy. The etiology of the disease is still unknown, and there are arguments that the disease is associated with viral infections, but it has not been determined which viral infections can cause the disease.
Clinical manifestations: The characteristic manifestations are various forms of seizures, progressive hemiparesis, and mental retardation. The main period of onset is childhood, with a mean age of onset of 6 years.
The typical course of the disease can be divided into 3 phases.
(1) Prodromal phase: infrequent seizures and mild hemiparesis with hemiparesis lasting an average of 7.1 months, although there are cases where the prodromal phase can last for several years. There may be no specific findings on brain imaging at this time. Some children have no prodromal manifestations and go directly to the acute phase.
The acute phase is characterized by frequent seizures in the form of simple limited motor seizures, often in the form of persistent restrictive epilepsy (EPC), with progressive hemiparesis, hemianopia and cognitive impairment. Aphasia occurs if the dominant cerebral language hemisphere is damaged. The average duration of the acute phase is 8 months.
(iii) Posterior phase: In this phase, the disease no longer progresses, but neurological damage persists and seizures still occur, less frequently than in the acute phase.
Diagnosis: The diagnosis of this disease relies on clinical, EEG, and MRI, and some patients still require histopathological examination. Early diagnosis is difficult because the brain imaging changes are not obvious in its prodromal phase, but early immunosuppressive therapy is effective. Therefore, it is significant to perform early diagnosis for patients.
The diagnostic criteria proposed by Bien et al. are divided into two parts, A and B. Part A.
(i) focal epilepsy (with or without persistent restrictive epilepsy) and cortical damage on one side.
(ii) EEG showing slow waves with or without discharges in one hemisphere.
③MRI shows focal cortical atrophy in one hemisphere with at least one of the following: gray matter or white matter T2/FLAIR high signal.
ipsilateral caudate nucleus head high signal or atrophy. part B.
(i) persistent restrictive epilepsy or progressive cortical damage on one side.
(ii) Progressive focal atrophy of one hemisphere on MRI.
If the brain tissue is infiltrated with T cells and microglia, RE can be ruled out if there are more macrophages, B cells or plasma cells or viral inclusions in the brain tissue. if 3 indicators in part A or 2 indicators in part B are present, RE can be diagnosed. if brain biopsy is not available, gadolinium-enhanced MRI and cranial CT are feasible to demonstrate the lack of gadolinium enhancement and calcification to rule out other disorders that can cause hemiparesis.
Treatment: Antiepileptic drugs have no clear efficacy in the treatment of EPC, but can still be effective for other types of seizures. Immunosuppressants, immunomodulators and antiviral therapy have been used clinically, but the efficacy is not definite. Significant effects of early immunosuppressive therapy have been reported. Immunotherapy includes.
①Corticosteroid therapy.
② Intravenous immunoglobulin therapy.
(iii) glucocorticoids + immunoglobulins.
④ plasma exchange (PEX) or protein AIgG immunosorbent (PAI).
⑤ Tacrolimus: an immunosuppressant that inhibits T-cell activity.
At this stage, the only effective method that can cure the disease is cerebral hemispherectomy, with a reported cure rate of 62% to 85%. The mortality rate of this procedure is 0-4%, and complications are 0-22%. Complications are mainly hemiplegia, hemianopia and speech disorders (if the main hemisphere is removed). Moreover, for children undergoing hemispherectomy, the younger the child is, theoretically, the better the functional recovery after surgery. Because of the ongoing development of brain halos and the strong developmental compensatory capacity and plasticity, the younger the child is, theoretically, the better. However, in terms of surgical trauma tolerance, children who are too young cannot be selected because hemispherectomy is very traumatic and children who are too young cannot withstand the surgical blow. It is considered that the best age for hemispherectomy is between 4 and 6 years.
Prognosis: The prognosis for Rasmussen’s encephalitis varies and, if left untreated, may lead to mental retardation and paralysis, with most children left with limb paralysis and aphasia. In some children, epilepsy can only be controlled surgically.