NQ-112: (E) This process is resulted from a chronic viral infection

Diagnosis: Rasmussen encephalitis

Pathology of the case: For mysterious reasons, Rasmussen encephalitis (RE) always affects only one side of the brain as illustrated here. It is an inflammatory disease of the brain occurring most often in children (<15 yrs.). It is characterized by chronic inflammation involving one cerebral hemisphere and typically results in seizures, hemiparesis, and cognitive difficulties. While the underlying cause is unknown, the process is mediated by T cells, with neuronal loss, gliosis, and microglial activation of the affected region. The possibility of a viral infectious agent has been suspected for a long time but no such agent has ever been found. Antibodies against glutamate GluR3 receptors has have been associated with Rasmussen encephalitis but more recent studies show that these antibodies can be found in other epilepsy patients.

Reference:

• Watson R, Jiang Y, Bermudez I, Houlihan L, Clover L, McKnight K, Cross JH, Hart IK, Roubertie A, Valmier J, Hart Y, Palace J, Beeson D, Vincent A, Lang B. Absence of antibodies to glutamate receptor type 3 (GluR3) in Rasmussen encephalitis. Neurology. 2004 Jul 13;63(1):43-50.

• Mantegazza R, Bernasconi P, Baggi F, Spreafico R, Ragona F, Antozzi C, Bernardi G, Granata T. Antibodies against GluR3 peptides are not specific for Rasmussen's encephalitis but are also present in epilepsy patients with severe, early onset disease and intractable seizures. J Neuroimmunol. 2002 Oct;131(1-2):179-85.

RE has an acute stage, where the inflammation is active and neuronal damage is occurring, followed by a chronic (residual) stage, where the inflammation has subsided but the damage remains. In some cases, a prodrome may be identified for a period of time prior to the onset of symptoms. Initially, the treatment involves managing the inflammation with steroids and possibly immunomodulation therapies. In the chronic stage, treatment is focused on improving symptoms. RE patients frequently experience seizures that are often refractory to medical management. Epilepsia partialis continua is a condition in which patients experience focal recurrent motor epileptic seizures, and may be seen in patients with RE. When seizure activity is persistent and/or refractory to medical management, a hemispherectomy (surgical removal of affected hemisphere) may be performed to remove the source of the seizures.