Abstracts

The cause of Rasmussen[apos]s syndrome (RS) is unknown. Many investigators have suggested that RS may be an autoimmune disorder due to heterogeneous etiologies resulting in similar clinical, electroencephalographic, radiographic, and pathologic characteristics. The criteria necessary and sufficient to make the diagnosis of RS are still being defined. The 6^th European Congress on Epileptology in Vienna recently proposed consensus criteria for the diagnosis of RS (Bien et al., Brain 2005;128:454-471). We report three patients with clinical characteristics consistent with the proposed diagnostic criteria for RS, who had incongruent pathologic findings based on surgical specimens from hemispherectomy or multilobar resection. Thirty-two patients admitted to UCLA between January 1992 and February 2005 who had clinical findings consistent with RS and who underwent operative treatment, selected via the UCLA Pediatric Epilepsy surgical database, were reviewed. All 32 patients, including the three patients reported here, had clinical characteristics consistent with the diagnosis of RS: medically intractable focal seizures and focal neurologic deficits localizing to one cerebral hemisphere, electroencephalography showing unihemispheric slowing and epileptogenic zones, and MRI findings of focal cortical atrophy of one cerebral hemisphere (adapted from Bien et al., Brain 2005;128:454-471). Three of these 32 patients did not have pathologic findings consistent with RS based on surgical specimens. The extensive pathologic specimens from these three patients revealed only focal Chaslin[apos]s gliosis and no diagnostic abnormality, including no active inflammation. No microglial nodules, microvascular proliferation, or cystic cavitation were present, and no other signs of chronic inflammation apart from rare foci of perivascular lymphocytic cuffing around a few cortical/leptomeningeal arteries were found. These three patients may represent a subgroup of RS patients whose disease is due to a specific singular pathogenetic mechanism. Separating RS patients into distinct subgroups based on their pathologic findings will help to elucidate the different pathogenetic mechanisms that result in the classical clinical picture of RS. (Supported by NIH grant R01 NS38992 and P05 NS02808.)