Rasmussen syndrome is a specific disorder that presents primarily as chronic progressive partial epilepsy with progressive hemiparesis and cognitive dysfunction in children. It was first reported by Rasmussen in 1958 and is less common clinically. It differs from general types of epilepsy in its pathogenesis, treatment principles and prognosis. The child, a 4-year-old female, was admitted to the hospital with “seizures of the left side of the face and left limb and slurred speech for five months. The patient had a sudden onset of slurred speech and salivation for no apparent reason 5 months ago, followed by twitching of the limbs and a call that lasted 10 seconds. The seizures were gradually more frequent, with the mouth tilted to the left, left-sided facial and hand and foot twitching predominantly, without consciousness impairment, and each seizure could last for 5-30 minutes, with another seizure at an interval of more than 10 minutes. He was treated with antiepileptic drugs such as clonidine, phenobarbital and carbamazepine with poor efficacy. No special past history. He was admitted to the hospital for physical examination: good development, good response, normal intelligence, lack of fluent speech, bilateral pupils were always alternating between large and small, tongue extension left, symmetrical muscle tone of the limbs, muscle strength of the right limb grade V, left limb muscle strength III, muscle fullness, hyperalgesia of the left hemiplegia, finger-nose test was accurate, bilateral pathological signs (-). Lumbar puncture cerebrospinal fluid examination showed no abnormalities in routine, biochemical, oligoclonal bands, immunoglobulins, and antibodies to CMV, HSV, RV, and TOXO (-). The right central, parietal and occipital lobes were characterized by the continuous appearance of high-amplitude spike and slow-wave complexes”. “long T2 signal with blurred borders in the right lateral paraventricular, right frontal and left temporal lobes”. Diagnosis: partial persistent epilepsy, Rasmussen’s syndrome. Treatment with the addition of Toltea and Depakene had no significant effect, but chloral hydrate relieved the seizures for several hours. The child also did not respond to antiviral drugs, prednisone, or immunoglobulin therapy. A right hemispherectomy was suggested to the parents, which was refused and the child was discharged automatically. 2. Discussion The etiology of Rasmussen’s syndrome is unknown. Early studies suggested that it was a viral infection causing encephalitis, so the syndrome was once called “Rasmussen’s encephalitis”. Although there have been isolated clinical reports of viral associations, no definitive virological evidence has been found. Some cases have a history of infection prior to the onset of the disease, but they are not epidemic and are mostly disseminated. Many studies now consider the syndrome to be an immune response induced by viral infection, and it is an autoimmune disease like multiple sclerosis that progressively worsens as the disease progresses from an early inflammatory response involving T lymphocytes and glial cells to late neurogenic death and vacuole formation in the cerebral cortex. However, herpesvirus infection is not directly related to Rasmussen syndrome. Many studies have identified autoantibodies against glutamate antigen receptor (anti-GluR3) in the serum of patients. Animal studies have confirmed that after application of GluR3 protein to rabbits immunized with anti-GluR3 antibodies, the rabbits developed anti-GluR3 antibodies and developed seizures and movement disorders similar to those seen in human Rasmussen syndrome. It has been reported in the literature that the detection rate of anti-glutamate antigen receptors in the serum of patients with Rasmussen syndrome was 82%, compared to 64% in patients with partial epilepsy. It has also been found that anti-GluR3 antibodies are not commonly found in Rasmussen syndrome and refractory epilepsy. Rasmussen syndrome occurs most often in children, but can also be seen in adolescents and adults. Most commonly, the first symptom is a myoclonic seizure, but it can also be a simple partial seizure, a complex partial seizure, or a secondary generalized seizure, often presenting as a partial seizure continuum with clear consciousness and involving any small muscle group, such as one side of the mouth, face, fingers, or lower extremities. Seizures, however, are not an obligatory symptom of Rasmussen syndrome. In particular, brain damage caused by AIDS can also manifest as partial status epilepticus. Hart believes that when a child presents with partial epilepsy, at least one of the following must be present to make the diagnosis: (1) progressive neurological impairment at the onset of epilepsy or later; (2) progressive cranial CT or MRI suggestive of (2) Progressive hemispheric atrophy with hypointense on CT or abnormal signal on MRI; (3) Positive oligoclonal bands on cerebrospinal fluid examination; (4) Brain biopsy pathology confirming chronic encephalitis. In addition, the interictal EEG of Rasmussen syndrome shows diffuse slow waves or multifocal spike waves in the contralateral cerebral cortex of the affected limb, and sometimes bilateral independent epileptic discharges can be seen; the head MRI shows atrophy of one cerebral hemisphere, long T2 signals in the frontal, temporal and parietal lobes or partial lobar hypoplasia. Therefore, a comprehensive evaluation of the patient’s clinical features, EEG performance, neuroimaging and serological data is crucial for a definitive diagnosis. Almost all antiepileptic drugs have no satisfactory efficacy in Rasmussen syndrome. Antiviral drug therapy has also not shown definite clinical efficacy. However, there have been studies using ganciclovir for Rasmussen syndrome with 1.5 years of seizure-free follow-up, so it is recommended that when the disease is suspected, antiviral medication should be administered as soon as possible. Because of the possibility of genetic coupling between epilepsy and immunodeficiency, patients with epilepsy may also develop immunodeficiency after long-term antiepileptic drug therapy, producing antibodies that lead to immune-mediated damage to the cerebral cortex, making immunomodulation an important aspect of the treatment of Rasmussen syndrome.Frucht reported a 19-year-old female patient with Rasmussen syndrome who had a combination of dystonia and chorea hysterotica, which improved in a short period of time after immunoglobulin therapy. Most studies have concluded that immunoglobulin therapy is a treatment worth trying, but is generally effective in the short term, with poor long-term efficacy in halting the progression of the disease. There is growing evidence that focal lateral hemispherectomy is significantly more effective than partial resection for seizure control, reducing seizures by 60% – 80%. The shorter the duration of the disease and the younger the age, the better the outcome. After years of follow-up, there is further improvement in both psychomotor development and social functioning. Therefore, early surgical treatment is currently considered very important and should be aggressively pursued once the diagnosis is clear, rather than waiting too long for drug therapy alone and delaying the disease.