Limbic encephalitis secondary to malignant thymoma

Thymoma and Autoimmune Encephalitis: Clinical Manifestations and Antibodies

OBJECTIVE

To report the clinical, neuroimaging, and antibody associations in patients with autoimmune encephalitis (AE) and thymoma.

METHODS

A retrospective cohort study of 43 patients was conducted. Antibody determination and immunoprecipitation to characterize novel antigens were performed using reported techniques.

RESULTS

Patients' median age was 52 years (range: 23-88 years). Forty (93%) had neuronal surface antibodies: gamma-aminobutyric acid receptor A (GABA_AR) (15), amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor (AMPAR) (13), contactin-associated protein-like 2 (CASPR2) (4), leucine-rich, glioma inactivated 1 (LGI1) (3), glycine receptor (GlyR) (3), and unknown antigens (2). Concurrent antibodies against intracellular antigens occurred in 13 (30%; 9 anti-collapsin response mediator protein 5 [CRMP5]) and were more frequent in anti-AMPAR encephalitis (54% vs 20%; p = 0.037). The most common clinical presentation was encephalitis with multiple T2/fluid-attenuated inversion recovery hyperintense lesions in 23 (53%) patients (15 GABA_AR, 5 AMPAR, and 1 unknown neuropil antibody), followed by encephalitis with peripheral nerve hyperexcitability in 7 (16%; 4 CASPR2, 2 LGI1, and 1 unknown antibody), limbic encephalitis in 6 (14%; 4 AMPAR, 1 LGI1, and 1 antibody negative), progressive encephalomyelitis with rigidity and myoclonus in 4 (9%; 3 GlyR and 1 AMPAR antibodies), and encephalitis with normal MRI in 3 (7%; AMPAR antibodies). Anti-GABA_AR encephalitis was more prevalent in Japanese patients compared with Caucasians and other ethnicities (61% vs 16%; p = 0.003). In anti-AMPAR encephalitis, 3/4 patients with poor and 0/6 with good outcome had concurrent CRMP5 antibodies (p = 0.033). Immunoprecipitation studies identified metabotropic glutamate receptor 3 antibodies that were additionally found in 5 patients (3 with and 2 without encephalitis).

CONCLUSIONS

AE in patients with thymoma include several clinical-radiologic syndromes that vary according to the associated antibodies. Anti-GABA_AR encephalitis was the most frequent AE and occurred more frequently in Japanese patients.

Autoimmune Encephalopathies

BACKGROUND

Evaluation of patients with recent onset of progressive cognitive and behavioral problems can be challenging. Psychiatric disorders, metabolic derangements, toxins and infections are generally considered in the differential diagnosis along with prion disorders (Creutzfeldt-Jakob disease) and rapidly progressive degenerative dementias. Some subacute encephalopathies are caused by autoimmune or inflammatory mechanisms, recognized by the association with autoantibody markers and/or clear response to immunomodulatory treatment. This review describes the clinical features of these potentially reversible autoimmune encephalopathies.

REVIEW SUMMARY

Morvan syndrome, paraneoplastic limbic encephalitis (PLE), and nonparaneoplastic autoimmune limbic encephalitis have characteristic clinical and serological features. Limbic encephalitis is characterized by short-term memory impairment, complex partial temporal lobe seizures and psychiatric symptoms. Signal abnormalities in the mesial temporal lobes without contrast enhancement are the typical MRI findings. Morvan syndrome presents with behavioral changes, hallucinations, severe insomnia, autonomic hyperactivity and neuromyotonia (spontaneous muscle activity). Corticosteroid-responsive encephalopathy associated with evidence of thyroid autoimmunity (sometimes called Hashimoto encephalopathy) has a broad range of clinical presentation. Cognitive impairment with tremor, seizures, stroke-like events (including transient aphasia) and normal thyroid hormone levels is a common scenario. In the absence of diagnostic serological findings, clinical improvement with corticosteroids may be the only evidence of autoimmune encephalopathy.

CONCLUSIONS

Autoimmune encephalopathies are an important cause of rapidly progressive cognitive and behavioral decline that probably remain under recognized. Electroencephalography, brain MRI, cerebrospinal fluid examination and serological tests are useful diagnostic tools. With increased clinical suspicion, these diseases may be diagnosed and treated successfully.

Amygdaloid kindled seizures can induce functional and pathological changes in thymus of rat: role of the sympathetic nervous system

The present study sought to determine the effects of long-term kindled seizures of the basal amygdala upon immune function in rat, utilizing the thymus, as a principal target for study. Histopathology from kindled Sprague-Dawley rats revealed the presence of epithelial cell thymoma in 70% of these rats. The results revealed an increased rate of apoptosis and proliferation in thymic epithelial cells. Analysis of thymocytes indicated a decrease in the ratio of CD4 to CD8 positive T cells and reduced proliferative response to T-cell mitogens. To determine whether these effects were mediated through the sympathetic nervous system, animals were treated with guanethidine, which blocked the development of epithelial cell thymomas, while mifepristone treatment, employed to determine the possible role of the hypothalamic-pituitary axis, was ineffective in attenuating thymoma development. Thus, the present study demonstrated that functional and pathological changes in the thymus during kindled seizures are mediated through the sympathetic nervous system.

Potentially reversible autoimmune limbic encephalitis with neuronal potassium channel antibody

OBJECTIVES

To describe the clinical features and coexisting serum autoantibodies in seven patients with encephalitis associated with autoantibodies to alpha-dendrotoxin-sensitive voltage-gated potassium channels (VGKCs), and to compare this disorder with other autoimmune encephalopathies.

METHODS

Clinical information was obtained from a retrospective review of medical records and telephone interviews. All autoantibody testing was performed in a single laboratory.

RESULTS

The seven patients were examined for subacute cognitive and behavioral changes. Seizures, usually temporal-onset complex partial type, were documented in six patients, and all seven patients had EEG abnormalities. None had symptoms or signs of neuromuscular hyperexcitability. One described hypersalivation. Four patients had additional autoantibody markers of neurologic autoimmunity (muscle acetylcholine receptor, striational, P/Q-type calcium channel, or GAD65), and two had thyroperoxidase antibodies. Two patients had a history of cancer: one had active prostate adenocarcinoma, and the second had a remote history of tongue carcinoma. Cranial MRI demonstrated mesial temporal lobe abnormalities in all patients. One patient improved spontaneously, and six were treated with IV methylprednisolone. Three improved remarkably with treatment. At follow-up evaluation, one had no cognitive deficits, four had mild persistent short-term memory dysfunction, and two had persistent disabling behavioral deficits.

CONCLUSIONS

Voltage-gated potassium channel antibodies are a valuable serologic marker of a potentially reversible autoimmune encephalopathy. The neurologic manifestations of this disorder are indistinguishable from paraneoplastic limbic encephalitis but are distinct from Morvan syndrome and Hashimoto encephalopathy.

Fulminant autoimmune cortical encephalitis associated with thymoma treated with plasma exchange

A 55-year-old man presented with fever, malaise, dysarthria, and intermittent twitching of his right hand. He progressed rapidly to aphasia, intractable myoclonic seizures, and unresponsiveness. Magnetic resonance imaging (MRI) of the head demonstrated multiple nonenhancing areas of signal abnormality involving the cortex of both cerebral hemispheres. Extensive evaluation revealed no infectious cause for his symptoms. Muscle acetylcholine receptor binding and modulating antibodies, striational antibodies, and a neuronal autoantibody specific for collapsin response-mediator protein were detected. An invasive thymoma was discovered and resected. Brain biopsy revealed microglial activation, gliosis, and scant perivascular lymphocytic inflammation. His condition worsened despite treatment with anticonvulsants, intravenous corticosteroids, and antimicrobials. Plasma exchange was performed. The myoclonus stopped; he regained consciousness and gradually improved to the point that he could talk and ambulate with assistance. An MRI revealed regression of the lesions with residual cortical atrophy. This case demonstrates that paraneoplastic encephalitis may occur with thymoma and may extend to cortical regions outside the limbic system.

Limbic encephalitis and hyperactive foci on PET scan

Two cases of patients with paraneoplastic limbic encephalitis, difficult to control seizures, and unilateral hippocampal hypermetabolism on positron emission tomography (PET) are described. Two women aged 33 and 61 presented with uncontrolled complex partial seizures, profound memory loss and cognitive decline. One was later diagnosed with breast cancer and the other with lung cancer. Video-EEG on the first patient recorded multifocal sharp waves and bilateral independent seizure onsets. The second patient had no epileptiform discharges and bitemporal ictal onset, even though the clinical seizures suggested a right temporal onset. Magnetic resonance imaging (MRI) was normal in both patients. PET scans obtained in the interictal state showed right hippocampal hypermetabolism in both patients. In the second patient, the lung cancer was irradiated with resolution of seizures and improvement of memory function. A PET scan six months later was normal. Subsequent seizure recurrence and worsening of memory led to the discovery of widespread metastases. Limbic encephalitis should be considered in the differential diagnosis of intractable partial epilepsy, particularly if accompanied by severe memory loss and cognitive decline. Treatment of the underlying cancer may be lead to improved seizure control. Hippocampal hypermetabolism may be a common feature on PET, and may indicate subclinical seizure activity.

Morvan's fibrillary chorea: a paraneoplastic manifestation of thymoma

Morvan's fibrillary chorea is a rare disease characterised by symptoms which include neuromyotonia, cramping, weakness, pruritus, hyperhidrosis, insomnia, and delirium. The first case of Morvan's fibrillary chorea to be associated with clinical manifestations of myasthenia gravis with thymoma, psoriasis, and atopic dermatitis is reported. Muscle histopathology disclosed chronic denervation and myopathic changes and in vitro electrophysiology demonstrated both presynaptic and postsynaptic defects in neuromuscular transmission. Serum antibodies to acetylcholine receptors, titin, N-type calcium channels, and voltage gated potassium channels were detected. Plasmapheresis, thymectomy, and long term immunosuppression induced a dramatic resolution of symptoms. The association of thymoma with other autoimmune disorders and autoantibodies, and prolonged and sustained remission with chronic immunosuppression, place Morvan's fibrillary chorea on the range of neurological diseases arising as a paraneoplastic complication of cortical thymomas.

Thymoma: a multivariate analysis of factors predicting survival

BACKGROUND

Despite complete surgical excision, malignant thymomas often recur with resultant death. We reviewed our series to determine which factors independently predict survival after surgical resection.

METHODS

A retrospective analysis of patients operated on for thymoma between 1949 and 1993 at Memorial Sloan-Kettering Cancer Center was performed. Clinical data were collected from chart review. Only patients with a pathology report confirming the diagnosis of thymoma were included in this analysis. Kaplan-Meier survival curves were generated and comparisons of survival analyzed by log rank test. Multivariate analysis was performed by the Cox proportional hazard model.

RESULTS

One hundred eighteen patients with thymoma underwent operation. There were 86 complete resections (73%), 18 partial resections (15%), and 14 biopsies (12%). By Masaoka staging, 25 patients were stage I (21%), 41 stage II (35%), 43 stage III (36%), and 9 stage IVa (8%). Overall survival was 77% at 5 years and 55% at 10 years. Tumor recurred in 25 (29%) of 86 completely resected thymomas. Stage of disease (p = 0.03) was the only independent prognostic factor affecting recurrence. By multivariate analysis, stage (p = 0.003), tumor size (p = 0.0001), histology (p = 0.004), and extent of surgical resection (p = 0.0006) were independent predictors of long-term survival.

CONCLUSIONS

Patients with stage I disease require no further therapy after complete surgical resection. Neoadjuvant therapy should be considered for patients with large tumors and invasive disease.

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.