Paraneoplastic encephalitis

Case contributed by Dr Michael Burns

Presentation

Subacute diplopia, confusion and headache. Right gaze palsy on exam.

Patient Data

Age: 65 years
Gender: Female
MRI

Abnormal ill-defined T2 signal increases in the medial temporal lobe regions bilaterally and more superiorly in the inferior frontal lobe periventricular and caudate nuclei regions. There is also an abnormal T2 signal increase in the posterior limb of the left internal capsule, the right cerebral peduncle and right pons. Patchy contrast enhancement is seen in the medial temporal lobe regions bilaterally.  There is mild restricted diffusion in the medial left temporal lobe.  There is no appreciable mass effect.  No extra-axial fluid collections are present.  No other abnormality is noted.  

IMPRESSION:  
Bilateral temporal lobe and frontal lobe, right midbrain and right pons lesions are present, likely representing infectious encephalitis.  Limbic encephalitis would also be considered in the appropriate clinical setting. Gliomatosis is considered unlikely.

Lumbar puncture: Protein 1.08 g/L (elevated). WCC 23 x106/L (elevated).  High positive for antibodies to PNMA2(Ma2/Ta)

CT chest/abdo/pelvis: Right infrahilar mass.

Endobronchial ultrasound-guided right hilar lymph node biopsy: Non-small cell lung carcinoma.

Case Discussion

This is a case of anti-Ma2/Ta-associated encephalitis, representing a form of paraneoplastic encephalitis.

Anti-Ma2/Ta-associated encephalitis may manifest as isolated or combined limbic, diencephalic or brainstem encephalitis. Typical clinical features include confusion and eye movement abnormalities. CSF analysis typically shows inflammatory changes. The most common underlying malignancy is testicular cancer, followed by lung cancer.

This patient's neurological symptoms improved significantly following treatment with intravenous methylprednisolone.

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