Pitfalls in clinical diagnosis of anti-NMDA receptor encephalitis.

OBJECTIVES: To report pitfalls in the clinical diagnosis of anti-N-methyl-D-aspartate receptor (NMDAR) encephalitis. METHODS: We retrospectively reviewed the clinical information of 221 patients with clinically suspected autoimmune neurological disorders who underwent testing for autoantibodies against neuronal cell-surface antigens between January 1, 2007 and September 10, 2017. Forty-one patients met the diagnostic criteria for probable anti-NMDAR encephalitis (probable criteria), but one was excluded because neither serum nor CSF was examined at the active stage. Thus, in 220 patients, sensitivity and specificity of the probable criteria were assessed. RESULTS: NMDAR-antibodies were detected in 34 of 40 patients (85%) with the probable criteria; however, 2 of the 6 antibody-negative patients had ovarian teratoma. The median age at onset was higher in antibody-negative patients than those with antibodies (49 vs. 27 years, p = 0.015). The age at onset was associated with the probability of antibody detection (p = 0.014); the probability was less than 50% in patients aged 50 years or older. NMDAR-antibodies were also detected in 5 of 180 patients who did not fulfill the probable criteria; these patients presented with isolated epileptic syndrome (n = 2), atypical demyelinating syndrome (n = 2; one with aquaporin 4 antibodies), and autoimmune post-herpes simplex encephalitis (post-HSE) (n = 1). Sensitivity and specificity of the probable criteria was 87.2 and 96.7%, respectively. CONCLUSION: The probable criteria are valid, but the diversity of clinical phenotype should be taken into account in diagnosing anti-NMDAR encephalitis particularly in patients aged 50 years or older, or with isolated epileptic syndrome, atypical demyelinating syndrome, or post-HSE.

A Case of Paraneoplastic Limbic Encephalitis in a Patient with Invasive Thymoma with Anti-Glutamate Receptor Antibody-Positive Cerebrospinal Fluid: A Case Report.

BACKGROUND: Thymoma is known to cause autoimmune neuromuscular disease. However, anti-glutamate receptor antibody limbic encephalitis (LE) with thymoma is relatively rare. CASE PRESENTATION: A 68-year-old woman was admitted with progressive memory impairment and personality change. Brain magnetic resonance imaging (MRI) revealed high intensity in the bilateral limbic areas on T2-weighted fluid-attenuation inversion recovery (FLAIR) images. Chest computed tomography revealed a mass in the anterior mediastinum. Surgical resection of the tumor, which was consistent with a type B3 thymoma, resulted in clinical improvement. After surgery, the cerebrospinal fluid (CSF) was found to be positive for anti-N-methyl-D-aspartate (NMDA) type glutamate receptor antibodies. These findings led to the diagnosis of paraneoplastic LE (PLE) associated with thymoma. CONCLUSION: When a patient presents with neurologic symptoms of unknown origin, the possibility of LE accompanied by thymoma should be considered. Rapid treatment is desirable before the symptoms become irreversible.

Effects of L-Dopa and pramipexole on plasticity induced by QPS in human motor cortex.

Abnormal plasticity has been reported in the brain of patients with Parkinson's disease (PD), especially in the striatum. Although both L-Dopa and dopamine agonist remain to be the mainstay of the treatment in PD, their differential effects on cortical plasticity are unclear. We applied quadripulse stimulation (QPS) over the primary motor cortex (M1) in ten normal subjects to induce bidirectional long-term motor cortical plasticity. A long-term potentiation (LTP)-like effect was induced in the primary motor cortex (M1) by high-frequency QPS5 (interpulse interval of 5 ms) over M1, whereas a long-term depression (LTD)-like effect was induced by low-frequency QPS50 (interpulse interval of 50 ms), and the effects lasted up to 90 min after the stimulation pulses have ceased. In a double-blind randomized placebo-controlled crossover design, L-Dopa carbidopa 100 mg, pramipexole 1.5 mg [150 mg LED (L-Dopa equivalent dose)], or placebo was administered to the subjects 30 min before applying QPS. L-Dopa enhanced both LTP- and LTD-like plasticity as compared to placebo. In contrast, neither an LTP-like effect nor an LTD-like effect was modulated by pramipexole. The lack of LTP enhancement by pramipexole is compatible with the finding that D1 activation strengthens LTP because pramipexole is almost purely a D2 agonist. The lack of LTD enhancement by pramipexole is also consistent with the finding that both D1 and D2 coactivation is required for LTD. This is the first report to show that dopamine enhances LTD as well as LTP in the human brain and that coactivation of D1 and D2 is a requisite for LTD enhancement in normal humans.

Ataxic hemiparesis: neurophysiological analysis by cerebellar transcranial magnetic stimulation.

The aim of this study was to investigate physiological mechanisms underlying ataxia in patients with ataxic hemiparesis. Subjects were three patients with ataxic hemiparesis, whose responsible lesion was located at the posterior limb of internal capsule (case 1), thalamus (case 2), or pre- and post-central gyri (case 3). Paired-pulse transcranial magnetic stimulation (TMS) technique was used to evaluate connectivity between the cerebellum and contralateral motor cortex. The conditioning cerebellar stimulus was given over the cerebellum and the test stimulus over the primary motor cortex. We studied how the conditioning stimulus modulated motor evoked potentials (MEPs) to the cortical test stimulus. In non-ataxic limbs, the cerebellar stimulus normally suppressed cortical MEPs. In ataxic limbs, the cerebellar inhibition was not elicited in patients with a lesion at the posterior limb of internal capsule (case 1) or thalamus (case 2). In contrast, normal cerebellar inhibition was elicited in the ataxic limb in a patient with a lesion at sensori-motor cortex (case 3). Lesions at the internal capsule and thalamus involved the cerebello-thalamo-cortical pathways and reduced the cerebellar suppression effect. On the other hand, a lesion at the pre- and post-central gyri should affect cortico-pontine pathway but not involve the cerebello-thalamo-cortical pathways. This lack of cerebello-talamo-cortical pathway involvement may explain normal suppression in this patient. The cerebellar TMS method can differentiate cerebellar efferent ataxic hemiparesis from cerebellar afferent ataxic hemiparesis.

[Two cases of posterior spinal artery syndrome (PSAS)].

We have reported two patients with posterior spinal artery syndrome. Both of them had sudden onset back pain, paraparesis, loss of deep sensation and bladder-bowel disturbances. MRI disclosed spinal cord lesions positioned at its posterior part including the posterior column or posterior horn at thoracic levels. Spinal artery syndrome is a rare disorder, especially the posterior spinal artery syndrome (PSAS). In our department, only ten patients had spinal artery syndrome out of 2,064 patients admitted to our hospital these 20 years. All the other 8 patients had anterior spinal artery syndrome. It supports the notion that PSAS is rare. The detection rate of PSAS may increase after the routine use of spinal MRI in clinical practice. Our two patients had bilateral, symmetric symptoms. These symmetric signs and symptoms are usually seen in PSAS. The bilateral posterior spinal arteries connect with each other through many complex anastomoses. Moderate blood flow insufficiency may produce no clinical symptoms because of compensation by these anastomoses. When symptoms appear, these anastomoses do not compensate blood flow deficit and may produce bilateral symptoms.

[Infliximab treatment trial in a patient with neuro-Behçet's disease unresponsive to other treatments].

A 22-year-old man with a previous uveitis episode was admitted to our hospital because of persistent hiccup. On admission, he presented right-upper quadrantanopia, mydriasis and lack of the light reflex in the left eye, left-sided hemiplegia, and bilateral pathologic hyperreflexia. The MR fluid attenuated inversion recovery images showed left side dominant, high intensity lesions on the brainstem and the diencephalon. The HLA-B51 was positive. The CSF IL-6 was extremely elevated (998 pg/ml: reference value < = 6.0 pg/ml). Based on these, we concluded he had the neuro-Behçet's disease and treated him by high dose intravenous corticosteroids. This treatment improved his symptoms and MRI lesions, and decreased the CSF IL-6 levels initially. On 13th day after the first his discharge, however, dysarthria appeared and the CSF IL-6 levels elevated again. In addition to the high dose intravenous corticosteroids therapy for acute attack, 15 mg/week of methotrexate was started to prevent the recurrence. Even with this prevention, meningitis related to neuro-Behçet's disease occurred within six weeks. We administered 5 mg/kg of infliximab intravenously at 0, 2, 6, and 14 weeks. After the infliximab treatment, his symptoms improved and the IL-6 levels decreased, and no recurrence has occurred. This case supports that infliximab, anti-TNF-alpha agent, is a good candidate for neuro-Behçet's disease treatment when it is resistant to conventional immunosuppressive agents such as corticosteroids or methotrexate.

[Wernicke encephalopathy in a non-alcoholic patient with diabetic nephropathy under hemodialysis].

A 75-year-old man with diabetic nephropathy treated with hemodialysis visited to a medical office because of slight fever, and received intravenous glucose infusion without any vitamins. Thereafter, he noticed gait disturbance and began to tell inconsistent stories. He was admitted to our hospital due to aggravation of these symptoms. On admission, he was disoriented and not able to sit by himself because of severe truncal ataxia without weakness. He had also gaze direction nystagmus. Based on clinical features, we considered him as having Wernicke's encephalopathy (WE) and treated him with 100 mg thiamine per day. The thiamine supply diminished these symptoms soon. Plasma thiamine level prior to the administration was 7 ng/ml, which confirmed the diagnosis. MRI did not disclose any abnormalities frequently seen in WE. WE is a life-threatening disease, and 'early detection, early cure' is important for recovering without sequelae. The thiamine deficiency is often seen in dialysis patients because of dietary restrictions as well as its loss during dialysis. This case gives us the caution; when hemodialysis patients present acute/subacute gait disturbance and/ or abnormal mental state, we should consider WE. Furthermore, high-risk patients, such as elderly patients under hemodialysis may need some supplement including thiamine even at preclinical stage.