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Images in Neurology
June 2005

Magnetic Resonance Imaging Findings in a Patient With Bilateral Limbic Encephalitis

Arch Neurol. 2005;62(6):1014-1015. doi:10.1001/archneur.62.6.1014

A 74-year-old man was referred to the outpatient clinic of the neurology department for assessment of cognitive dysfunction, recent memory problems, hallucinations, abnormal behaviors, and speech disturbances with subacute onset. His medical history was remarkable for hypertension. He had smoked for 20 years. Neurological examination findings showed alteration in mental status, cognitive impairment, and psychiatric symptoms, including hallucinations, confusion, mood lability, and disinhibition. An electroencephalogram showed no abnormality. Cerebrospinal fluid analysis was normal except for a mild elevation in protein content (0.47 g/L; normal range, 0.15-0.40 g/L). A cytological examination of cerebrospinal fluid showed no malignant cells. Results of the cerebrospinal fluid culture and viral serological tests were normal. Initial cranial magnetic resonance imaging revealed a bilateral and symmetrical increase in volume and T2 signal intensity of the hippocampi and parahippocampal gyri, as well as the amygdalae (Figure 1). These areas were hypointense on T1-weighted images, with no change in signal intensity after administration of intravenous contrast. No abnormality was noted on diffusion-weighted images. These findings were suggestive of limbic encephalitis (LE), which is diagnosed with increasing frequency in paraneoplastic disorders. A chest x-ray film, followed by computed tomography of the chest (Figure 2), showed a left-sided hilar mass with spiculated margins. Bronchoscopy and biopsy results yielded the diagnosis of small cell cancer of the lung. The patient was started on chemotherapy. During follow-up, his neurological symptoms did not improve.