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Limbic encephalitis

Limbic encephalitis (LE) is a clinical syndrome defined by subacutely evolving limbic signs and symptoms with structural and functional evidence of mediotemporal damage in the absence of a better explanation than an autoimmune (or paraneoplastic) cause. There are features common to all forms of LE. In recent years, antibody(ab)-defined subtypes have been established. They are distinct regarding underlying pathophysiologic processes, clinical and magnetic resonance imaging courses, cerebrospinal fluid signatures, treatment responsivity, and likelihood of a chronic course. With immunotherapy, LE with abs against surface antigens has a better outcome than LE with abs to intracellular antigens. Diagnostic and treatment challenges are, on the one hand, to avoid overlooking and undertreatment and, on the other hand, to avoid overdiagnoses and overtreatment. LE can be conceptualized as a model disease for the consequences of new onset mediotemporal damage by different mechanisms in adult life. It may be studied as an example of mediotemporal epileptogenesis.

Paraneoplastic autoimmune optic neuritis with retinitis defined by CRMP-5-IgG

Autoantibodies have defined two paraneoplastic visual disorders related to small-cell lung carcinoma: retinopathy ("CAR"-IgG [23kDa, recoverin]) and optic neuritis collapsin response-mediated protein 5 (CRMP-5-IgG [62kDa]). Among 16 patients with CRMP-5-IgG and optic neuritis (aged 52-74 years; all smokers, 9 women), we documented coexisting retinitis in 5. None had CAR-IgG. Fifteen had subacute vision loss, swollen optic discs, and field defects. Vascular leakage was evident at and remote from the disc; 5/5 tested had abnormal electroretinograms. Nine had striking vitreous cells. Vitrectomy showed reactive lymphocytosis (4/4), predominantly CD4(+) (1/1). Most patients had multifocal neurological accompaniments. Cerebrospinal fluid contained lymphocytes (7-32), elevated protein, multiple oligoclonal immunoglobulin bands, and CRMP-5-IgG. Three patients superficially resembled Devic's disease at presentation. One autopsied patient had predominantly CD8(+) T lymphocytes infiltrating optic nerve and spinal cord. Eleven patients had confirmed small-cell carcinoma; 1 had imaging evidence of lung cancer; 3 had renal or thyroid carcinoma. Full-length CRMP-5 protein was identified in normal retina and optic nerve by Western blot analyses. Photoreceptor cells, retinal ganglion cells, and nerve fibers exhibited CRMP-5-specific immunoreactivity. In summary, CRMP-5-IgG defines a paraneoplastic ophthalmological entity of combined optic neuritis and retinitis with vitreous inflammatory cells. Positive serology obviates the need for vitreous biopsy and expedites the search for cancer.

Paraneoplastic neurological syndromes: an update on diagnosis, pathogenesis, and therapy

Since the discovery of the first clinically relevant anti neuronal antibody specific for a paraneoplastic aetiology in 1985, the number of such reactivities has grown at a rate of about one per year. Clinicians can now diagnose a paraneoplastic syndrome much more easily. This ability is especially important because, typically, the neurological symptoms occur before the cancer is diagnosed. Early tumour diagnosis is essential, because effective treatment of the cancer still seems to be the most efficient treatment option for the neurological symptoms. Immuno modulatory therapy should, nevertheless, be initiated as early as possible and seems especially helpful for peripheral syndromes and limbic encephalitis. The recent fundamental advances in understanding of the autoimmune pathology of these disorders, especially the role of cytotoxic T cells, should eventually lead to more effective treatment options.

Paraneoplastic chorea associated with CRMP-5 neuronal antibody and lung carcinoma

Paraneoplastic chorea is described in 16 patients: 11 with limited small-cell carcinoma, 2 with lung cancer revealed by imaging, 1 with renal cell carcinoma, and 1 with lymphoma. All had CRMP-5-IgG; 6 also had ANNA-1 (anti-Hu), including 1 without evident cancer. Chorea was the initial and most prominent symptom in 11 patients, asymmetric or unilateral in 5 patients, and part of a multifocal syndrome in 14 patients. Basal ganglia abnormalities were revealed by magnetic resonance imaging and at autopsy (as perivascular inflammation and microglial activation). Four patients improved with chemotherapy, and 2 improved with intravenous methylprednisolone.