Reversible paraneoplastic limbic encephalitis

Temporal lobectomy for refractory status epilepticus in a case of limbic encephalitis

The authors report a case of status epilepticus secondary to limbic encephalitis that was successfully treated with temporal lobectomy. A 45-year-old woman presented in status epilepticus refractory to high-dose suppressive medical therapy. Magnetic resonance imaging of the brain showed T2- and FLAIR-weighted hyperintensities in the right temporal lobe, left and right frontal lobes, and pons. A lumbar puncture revealed normal findings. Continuous electroencephalography monitoring showed continued right temporal seizure activity. A paraneoplastic panel was positive for N-type voltage-gated calcium channels. Subsequent bronchial biopsy revealed small cell carcinoma of the lung. A right temporal lobectomy was performed due to refractory status, resulting in resolution of seizure activity and recovery of good neurological function. The authors describe their case and review the literature on surgical therapy for refractory status epilepticus and limbic encephalitis.

Paraneoplastic limbic encephalitis

Paraneoplastic limbic encephalitis (PLE) is a rare neurological consequence of a variety of cancers, most commonly originating from lung, breast and testis. The aetiology is believed to be immune-mediated, caused by tumour-induced autoimmunity launching an attack against one's own central nervous system. The patient may present with amnesia, depression, anxiety, seizures and/or personality changes. The onset of these symptoms may precede the diagnosis of malignancy by a period of up to 2 years. The malignancy may be occult and unless the syndrome is recognised, it may fail to be detected. The diagnosis of PLE is suggested by the clinical picture, MRI evidence of mesial temporal lobe abnormality and CSF abnormalities such as the presence of oligoclonal bands. It may be further supported by the presence of paraneoplastic antibodies in the serum. Immunosuppression has been tried in some cases but memory impairment is often irreversible. There are several case reports in the literature of paraneoplastic limbic encephalitis but few emphasise the resulting impact that this may have on the patient's quality of life and their carers. The accompanying amnesia is often far more distressing to the carers, who are aware of the limitations of treatment of the underlying malignancy. Hospices offer the appropriate palliative environment for such patients as well as physical and psychological respite to the carers.

Memory lost, memory regained: neuropsychological findings and neuroimaging in two cases of paraneoplastic limbic encephalitis with radically different outcomes

OBJECTIVE

To report two cases of paraneoplastic limbic encephalitis (PNLE) with similar clinical presentation, but dramatically different outcome and to highlight the role of neuropsychological and radiological evaluation in PNLE.

METHODS

Both patients underwent an extensive battery of neuropsychological tests designed to document general intellectual function, anterograde verbal and visual memory, naming, knowledge and executive ability. In addition, structural (CT and MRI) and functional (HMPAO-SPECT) brain scans were performed.

RESULTS

Both patients presented with fairly sudden onset of profound and persistent memory loss in the absence of other neurological symptoms. Their subsequently diagnosed small cell lung cancer was treated with a combination of radiotherapy and chemotherapy, leading to remission of the tumour. The memory of patient 1 recovered fully and he died from an unrelated cause 1 year later; neuropsychological testing showed a severe, but isolated, anterograde amnesia, brain MRI was normal and HMPAO-SPECT showed left medial temporal hypoperfusion. Patient 2 remained densely amnesic despite regression of her lung tumour; neuropsychological testing disclosed both anterograde and extensive retrograde amnesia together with more generalised cognitive deficits including anomia and executive impairments, MRI showed gross atrophy of the hippocampus and amygdala bilaterally, and HMPAO-SPECT showed pronounced frontal and temporal hypoperfusion.

CONCLUSION

Complete remission from PNLE may occur and seems to be associated with pure anterograde amnesia without evidence of structural hippocampal damage in MRI. By contrast, cognitive deficits beyond severe anterograde amnesia and evidence of destructive medial temporal lobe pathology on MRI seem to be poor prognostic features.

Reversible limbic encephalitis caused by ovarian teratoma

A 19-year-old woman developed memory loss followed by psychosis, coma, convulsion, and central hypoventilation requiring mechanical ventilation. MRI of the brain showed minimal changes, and SPECT imaging revealed a small region of increased uptake in the cortex. Intravenous acyclovir and high-dose corticosteroids were administered without any effect. An extensive work-up revealed an elevated serum alpha-fetoprotein (AFP) concentration and the presence of an ovarian tumor. Following resection of the tumor, an immature teratoma by pathology, the patient had significant recovery of her cognitive function with some psychotic sequela. Serum anti-neuronal antibody (anti-Hu) was negative both by immunohistochemistry and by Western blot analysis. A rare combination of paraneoplastic limbic encephalitis and brainstem encephalitis was the suspected diagnosis. Because the tumor contained a neuronal component, we propose an immunologic cross-reaction as the pathomechanism, but the lack of a specific antibody may suggest cell-mediated rather than globulin-mediated immunity.

Neuropsychological functioning in a patient with paraneoplastic limbic encephalitis

A 54-year-old woman with clinically diagnosed paraneoplastic limbic encephalitis secondary to adenocarcinoma of the lung is described. Neuropsychological evaluation revealed intact visual perception, visual construction, language, speeded processing, and verbal abstract reasoning in the presence of a severe anterograde amnesia for both verbal and visual information. A profound consolidation problem is discussed in view of other diseases of the mesial temporal lobes resulting in impaired consolidation of new material.

Limbic encephalitis and immunological perturbations in two patients with thymoma

Two patients with clinical and radiological evidence of limbic encephalitis associated with an invasive lymphoepithelial thymoma who improved after thymectomy and radiotherapy are reported. The serum of both patients and the CSF of one of them contained different types of antibodies that immunoreacted with human and rat brain and newborn rat thymus. After treatment of the tumour, the antibody titres decreased. Similar antibodies were not found in various controls. Two out of 16 patients with thymoma, myasthenia gravis, and no CNS involvement had low titres of antibodies reacting with the brain. It is suggested that in some patients with thymoma, an autoimmune reaction involving antigens common to the brain and thymus is possibly misdirected against the CNS.

Anti-tumour therapy in paraneoplastic neurological disease

Paraneoplastic neurological syndromes have attracted attention in recent years. Detection of auto-antibodies directed against CNS and PNS structures have suggested an autoimmune etiology. This review is based on reports from the past 10 years and summarizes the therapeutic results in 258 patients suffering from paraneoplastic neurological disease including paraneoplastic encephalomyelitis, sensory neuronopathy, cerebellar degeneration, motor neurone disease and stiff man syndrome. The results show that in some entities such as Lambert-Eaton syndrome successful treatment can be expected. In other syndromes such as subacute sensory neuronopathy or paraneoplastic cerebellar degeneration therapeutic success varies from 5 to 10%.