Adult-onset subacute sclerosing panencephalitis presenting as a degenerative dementia syndrome.

Abstract

Sirs: Subacute sclerosing panencephalitis (SSPE) is a chronic reactivated infection with measles virus causing progressive inflammation and gliosis of the brain, mostly in children with an average age of onset of 14 years. The clinical course initially is marked by changes in behaviour, followed by myoclonic jerks, seizures and motor abnormalities, accompanied by progressive dementia. Later in the course pyramidal signs, stupor and finally decorticate postures and coma ensue. The course is slowly progressive with death occurring within three years. Up to 10 % of cases show either a fulminant or prolonged course. Diagnosis is based on antibodies against measles virus, elevation of gamma-globulin fraction and positive oligoclonal bands of immunoglobulin (Ig) in the cerebrospinal fluid (CSF) [4]. The electroencephalogram (EEG) shows a characteristic abnormality with periodic bursts of 2to 3-persecond high voltage waves [3]. Magnetic resonance imaging (MRI) shows involvement of periventricular and subcortical white matter [1]. Although no effective treatment has been proven, oral isoprinosine and intrathecal application of alpha-interferon may prolong survival [5]. We report a case of a very late adult-onset of SSPE presenting as a degenerative dementia syndrome. The 38-year-old Turkish female patient was admitted to our department for the evaluation of a progressive dementia. First symptoms were apparent when she was aged 35 years. She first developed indifference to her job, became apathetic with decline in intellectual functions. Disorientation for time, place and parts of her own person followed, furthermore psychomotor slowing, flat affect, depression, but no paranoid-hallucinatory symptoms. The patient developed mild neurogenic bladder disturbance with urge-incontinence. There was no history of any vaccination. She had suffered from “the usual childhood diseases”, but the family could not state explicitly whether she had suffered from measles. Cranial MRI in the year of onset of symptoms and two years later demonstrated a progressive generalized cerebral atrophy without any white matter changes or gadolinium enhancement. EEG and visual and somatosensory evoked responses were normal. When we saw the patient three years after the first manifestation of symptoms, neuropsychological examination showed verbal perseverations, anomia, phonematic paraphasia, dysgraphia, dyslexia, ideomotor and ideatoric and spatial constructive apraxia. Mini-Mental State Examination Score (MMSE) was 9,5/30. Neurological examination was normal except for slight rigidity of all limbs and very mild gait ataxia. Examination of the CSF revealed a massively elevated titre of anti-measles IgG antibodies (38.880 mU/ml) on enzyme-linked immuno-sorbent assay (ELISA), also demonstrable in the serum (270.000 mU/ml), with negative IgM antibodies in the CSF and serum. Antibody index was 57.2 [calculated as (anti-measles CSF IgG titre/mg total protein CSF)/ (anti-measles serum IgG titre/mg total serum IgG)], proving local synthesis in the CSF. Oligoclonal bands were strongly positive in the CSF because of intrathecal production of IgG. Cell count (16/3) and total protein content (539 mg/l) of the CSF were slightly elevated. Beta-amyloid 1–42 was decreased (370 pg/ml), but tau-protein, neuronspecific enolase and protein 14–3–3 in CSF were normal. Cultures for bacteria and fungi were negative. Further evidence of infection was lacking in CSF and serum, including search for antibodies against rubella-, cytomegaly-, Epstein-Barr-, varicella-zoster-virus and against Borrelia burgdorfferi. The patient was discharged and therapy with oral isoprinosine and intrathecal application of alpha-interferon was recommended in her home country. We present a case of very late adult-onset SSPE in a female Turkish patient now aged 38 years with a very slow and chronic course of three years so far. Because the relationship between measles virus and SSPE had not been established until 1967, a case of adult-onset of SSPE with immunological detection of measles virus was only first described in 1973. Cases of adultonset of SSPE reported before this time therefore must be regarded as questionable [2]. A more recent review of cases of adult-onset SSPE reports a range of the age of onset from 20 to 35 years [6]. In the reported cases of SSPE in adults the clinical picture was quite characteristic, making the diagnosis likely. The case we present is notable for the clinical picture of an almost pure cortical dementia without any myoclonus, seizures or dystonia. MRI showed unspecific generalized progressive cerebral atrophy and EEG was normal. Examination of CSF with local synthesis of anti-measles IgG antibodies reLETTER TO THE EDITORS