An 84-year-old woman developed spontaneous recurring mutism. During the periods in which she was able to speak, she described that she had a peculiar delusion where her body was melting away. She did not obey orders although she was able to move her limbs spontaneously. Severe fluctuations in blood pressure measurements were observed; they were unaffected by postural changes. She also had urinary retention and constipation. Her psychiatric and autonomic symptoms showed marked daily and diurnal fluctuations. The brain MRI showed no abnormality in the limbic system or temporal lobes. The cerebrospinal fluid showed slightly elevated protein with normal cells counts. This case was initially thought to be an encephalopathy of unknown etiology. On subsequent testings she was shown to have positive anti-ganglionic acetylcholine receptor (gAChR) antibodies. Although the initial steroid pulse and intravenous immunoglobulin therapies markedly improved both psychiatric and autonomic symptoms, they turned ineffective in subsequent recurrences. We were not able to treat her with plasmapheresis or with other immunisuppressive drugs because of her poor general status, thus their effectiveness could not be determined. Judging from her clinical course, in which immunotherapy was effective although somewhat limited, a possible involvement of an autoimmune mechanism was suspected; however, the exact pathogenesis remains undetermined. It is possible that in this case there may have been an involvement of the immune system and that the patient might have had an encephalopathy with anti-gAChR antibodies.

The case is a 30-year-old woman. From the age of 25 years, she had several episodes of cortical blindness and visited a local doctor. Mitochondrial disease was suspected based on findings of cerebral infarction-like imaging and a history of diabetes. However, serum and cerebrospinal fluid lactate levels were normal and no abnormal muscle pathology was found. At the age of 30 years, she visited our hospital with impaired consciousness, cortical blindness, and tremor-like involuntary movements in the neck and right fingers. Brain MRI showed abnormal signals in bilateral basal ganglia, with an increased lactate peak by magnetic resonance spectroscopy and high cerebrospinal fluid lactate levels. Mitochondrial gene analysis identified a m.4296G>A gene mutation. Consequently, we reached a diagnosis of mitochondrial encephalopathy. Adult-onset mitochondrial encephalopathy with m.4296G>A gene mutation is extremely rare. This case showed clinical features caused by damage of both the cerebral cortex and subcortical basal ganglia.

A 76-year-old Japanese female who was treated with long-term use of prednisolone at 10 mg/day for interstitial pneumonia developed acute right-dominant lower limb paralysis and then upper limb paralysis with herpes zoster eruptions on the right C7–Th1 dermatomes. On admission, right predominant quadriplegia was observed with sensory symptoms; Hughes functional grade was level 4; the hand grip power was right, 0, and left, 7 kg, the deep tendon reflexes were abolished throughout without pathologic reflexes. Twenty days after the onset of the symptoms, the cerebrospinal fluid (CSF) revealed mild increases of lymphocytes (13 cells/μl) and protein content (73 mg/dl). Varicella-zoster virus (VZV) PCR was negative in the CSF, but an enzyme immunoassay for VZV was positive in her serum and CSF, and the high titers were prolonged. Peripheral nerve conduction and F wave studies suggested right-dominant demyelinating polyradiculoneuropathy. A T₁-weighted MR contrast image exhibited right-dominant high-intensity lesions on the C7–Th1 spinal roots and similar lesions on the L4–5 spinal roots. We compared with several similar cases from the literature and proposed that VZV itself involves the pathogenesis of the polyradiculoneuritis in immunocompromised hosts.

We describe a 60-year-old woman with medically refractory left mesial temporal lobe epilepsy accompanied by Ross syndrome. The patient had a partial triad of Ross syndrome with hypohydrosis only on her right side (contralateral to the epileptic seizure focus), Adie’s tonic pupil on the right, and areflexia while her seizures used to be medically refractory. However, her hypohidrosis and Adie’s tonic pupil have completely changed in terms of laterality following nearly complete seizure freedom resutling from left temporal lobectomy. This unique change in laterality in Ross syndrome is most likely caused by remote effects of the near-absent epileptic acitivity, and it also may contribute to understanding the pathophysiological mechanism of Ross syndrome.

A 60-year-old woman with a 3-day history of ataxic gait, blurred vision, and upper extremity paresthesia was admitted to our hospital. She presented with severe visual disturbances (finger counting), ophthalmoplegia, neck weakness, and sensory ataxia. Serum anti-GQ1b antibody, anti-GM3 antibody, and anti-GD3 antibody were strongly positive, which might contribute to the pathogenesis. Since we suspected Guillain-Barré syndrome (GBS), intravenous immunoglobulin therapy (IVIg) and high-dose steroid therapy were administered; however, improvements in her visual acuity were minimal. Additional IVIg and high-dose steroid therapy resulted in limited visual acuity improvements. Therapeutic strategies for patients with GBS and refractory optic neuropathy remain controversial.

A 49-year-old woman with hepatic failure owing to alcoholic liver cirrhosis went into a deep coma. Her serum ammonia concentration was elevated at 436 μg/dl, and she had a generalized convulsion. Electroencephalogram and cerebrospinal fluid examination did not suggest encephalitis and epilepsy. Hyperammonemia may be occur because of generalized convulsions; however, it can spontaneously resolve if the convulsions are stopped. If hyperammonemia is the primary cause of generalized convulsion, the serum ammonia concentration will remain high until the cause is eliminated. However, despite stopping the convulsions, her ammonia concentration remained high. Diffusion-weighted brain MRI revealed symmetric high-intensity lesions in the frontal, temporal, and parietal cortices, especially the cingulate and insular cortices of the bilateral hemispheres. These findings were in line with those of previous reports that revealed symmetric cortical lesions, including cingulate and insula cortices that are distinctive in acute hyperammonemic encephalopathy. Therefore, we diagnosed that the coma, generalized convulsions, and abnormal brain MRI findings were caused by acute hyperammonemic encephalopathy.

A 55-year-old man presented with recurrent brain infarction which had increased multifocally mainly in the cerebral white matter over the course of one year. Antibodies associated with antiphospholipid syndrome (APS) were initially negative. The patient was admitted to our department because of the thickened meninges shown on gadolinium enhanced brain MRI, mimicking hypertrophic pachymeningitis. However, blood and cerebrospinal fluid analysis revealed no significant inflammatory changes. On histopathological examination of the biopsied meninges, the arachnoid membrane was thickened with fibrosis, and arachnoidal microvessels were enlarged without significant inflammatory changes. The dura mater was not thickened, and no inflammation or microvessel enlargement were revealed. Finally, serum IgG anticardiolipin antibody testing was positive twice at an interval of more than 12 weeks, confirming the diagnosis of APS. Since initiating antithrombotic therapy with warfarin, brain infarction has not recurred. Without inflammation in the arachnoid membrane, the congestion of blood flow caused by thrombosis of microvessels in the arachnoid membrane might have increased the thickness of the arachnoid membrane.

A 17-year-old woman was admitted to our hospital because of a high fever, consciousness disturbance, and delirious behavior. Methicillin susceptible Staphylococcus aureus (MSSA) infection was confirmed by blood culture. Transthoracic echocardiogram showed no abnormality at first. Diffusion-weighted brain MRI showed a high intensity lesion in the middle portion of the splenium, which was shown as low intensity on apparent diffusion coefficient map. Then, antibiotics therapy was started against suspected bacterial meningitis, while the lumbar puncture was not performed because of the decreased number of platelets. Since the systolic murmur appeared at the apex on day 12, the diagnosis with infectious endocarditis was made by transthoracic echocardiogram. The MRI abnormalities disappeared on day 16 and we diagnosed her with clinically mild encephalitis/encephalopathy with a reversible splenial lesion (MERS) associated with infectious endocarditis. This case suggests that MERS can occur associated with infectious endocarditis caused by Staphylococcus aureus.