Many mutations of genes for ion channels result in some epilepsies. Their electrophysiological studies reveal pathophysiological mechanisms underlining epilepsy and also mechanism of action of several antiepileptic drugs. In this review, We briefly summarize pathophysiology of epilepsy and the mechanisms of antiepileptic drugs.

A 62-year-old woman had a prior ischemic stroke in the right temporal lobe with dysarthria and dysesthesia of the left hand. Embolic stroke of undetermined source (ESUS) was diagnosed and warfarin was administered. However, transient ischemic attack recurred upon admission to our hospital. Paroxysmal atrial fibrillation and cerebral arterial stenotic lesions were absent. Transesophageal echocardiography revealed a mobile hyperechoic structure on the aortic valve indicating papillary fibroelastoma. She was diagnosed with a brain embolism due to the intracardiac tumor which was surgically excised and pathologically confirmed as papillary fibroelastoma. This type of tumor is relatively rare but it is important as an embolic source especially in ESUS. Transesophageal echocardiography was indispensable for detecting the embolic source in this patient with ESUS.

A 49-year-old man was transferred to our hospital with chief complaint of global aphasia and weakness of right upper and lower limbs. Brain MRI showed ultra-acute cerebral infarction in left anterior cerebral artery and middle cerebral artery territory and MRA showed occlusion of A2 and M2. Although t-PA was administrated intravenously, symptoms didn’t improve and giant internal carotid thrombus (size 6 × 7 × 17 mm) was recognized at left internal carotid artery by carotid ultrasonography. After started anticoagulant therapy, thrombus was miniaturized gradually and finally disappeared. Anticoagulant therapy is effective to internal carotid thrombus and carotid ultrasonography is useful to confirm the effectiveness. We suggest that clinicians should enforce anticoagulant therapy for the first choice to internal carotid thrombus.

A 21-year-old woman underwent surgery for a pituitary tumor. On the 11th postoperative day, blood examination revealed severe hyponatremia, with a serum sodium level of 111 mEq/l, and two days later this increased rapidly to 137 mEq/l. On the 20th postoperative day, the patient developed dysarthria and gait disturbance. Head MRI on the 30th postoperative day demonstrated intense high-signal lesions in the pons and bilateral corpus striatum on FLAIR and DWI, and central pontine and extrapontine myelinolysis was diagnosed. The patient’s symptoms improved gradually after rehabilitation and antispasticity treatment. It was suggested that the changes in serum sodium levels after pituitary surgery were due to impaired secretion of antidiuretic hormone due to degeneration of nerve terminals in the posterior pituitary. As pituitary surgery may trigger changes in serum sodium leading to myelinolysis, this possibility should always be borne in mind when treating such patients.

We report an acute myelitis in a 53-year-old woman that occurred in 7 days after the diagnosis of Th5–6 herpes zoster. Clinical examination revealed hyperhidrosis of left side of her face, neck, arm and upper chest. She also had muscle weakness of her left leg and sensory impairment for light touch and temperature in her chest and legs. Spinal cord MRI demonstrated a longitudinal T₂-hyperintense lesion extending from Th1 to 7. In the axial imaging, the lesion dominantly located in the left side gray matter. Hyperhidrosis, weakness and sensory impairment were improved after intravenous therapy with acyclovir and methylprednisolone. VZV (varicella zoster virus) IgG index of the cerebrospinal fluid was high and serological anti aquaporin-4 antibodies were positive at the time of the admission. This case had both characteristics of VZV myelitis and neuromyelitis optica spectrum disorder. Myelitis relapsed 19 months after the first attack. We believe that sympathetic hyper reactivity due to thoracic spinal cord lesion was responsible for the hyperhidrosis in our patient.

We report a 74-year-old female patient with Parkinson disease (PD). Around 2010, she developed depression and bradykinesia and was diagnosed as PD. In July 2014, she came to our hospital, of which she lived in the neighborhood. In the last part of December 2014, she felt uneasy about her fecal smell and saw a psychiatrist in the first part of January 2015. Quetiapine (25 mg/day) was added. In the last part of January, she complained of fecal smell everywhere and could not take a meal. No-one else could detect the smell. A diagnosis of olfactory hallucination was made. The next day after increasing to 75mg/day, however, she was admitted to our hospital because of refusing to take medicine. After introducing donepezil, olfactory hallucination subsided and her appetite was improved. Brain MRI showed atrophy of the bilateral temporal lobes and N-isopropyl-p-(iodine-123)-iodoamphetamine single photon emission computed tomography (¹²³I-IMP-SPECT) revealed hypoperfusion in the bilateral mesial temporal lobes. We suppose that cholinergic denervation in the mesial temporal lobes is an important determinant of her olfactory hallucination.

A 62-year-old woman presented with paresthesia of limbs, gait disturbance, urinary retention and constipation following upper respiratory infection. Neurological examination revealed gait disturbance due to loss of position sense in her extremities with intact muscle power, and autonomic failure represented by orthostatic hypotension, constipation and autonomic bladder. Cerebrospinal fluid analysis showed normal cell counts with elevated protein levels. Nerve conduction study showed sensory nerve impairment with almost normal motor nerve conduction in her upper and lower extremities. Sympathetic skin response of both hands was unresponsive, indicating autonomic nervous dysfunction. We diagnosed her as having acute autonomic and sensory neuropathy (AASN) and treated her with intravenous immunoglobulin, which ameliorated her symptoms enabling her to walk without any assistance at the time of discharge. Screening tests of serum autoantibodies revealed positivity of antibody against a mixture of galactocerebroside (Gal-Cer) and phospholipids. According to previous literature, no specific antibodies have been identified in AASN. This case, therefore, suggests a possible role of anti-Gal-Cer antibody in the pathogenesis of AASN.

A 46-year-old man presented with a history of personality change and memory disturbance for 5 months. He gradually became difficult in doing a daily job. Brain MRI showed abnormal hyperintensity within bilateral mesial temporal lobes on T₂ weighted image. Therefore, viral and autoimmune limbic encephalitis was initially suspected. However, because treponemal and non-treponemal specific antibodies were positive in serum and cerebrospinal fluid (CSF), the diagnosis of neurosyphilis was made. Patients of neurosyphilis with mesiotemporal T₂ weighted hyperintensity reportedly showed common features such as relatively young age, HIV-negative, subacute cognitive impairment and seizure, as seen in our patient. Neurosyphilis should be included in the differential diagnosis for mesiotemporal abnormality in patients with these features. In addition, in our patient, anti-glutamate receptor ε2 antibody (ELISA) was strongly positive in CSF that suggested additional autoimmune pathophysiological mechanism.

A 21-year-old man was admitted to our hospital in June 2015. He felt paresthesia of toes in April 2015, which had been spreading upward, and he became difficult to walk in June. Nerve conduction study showed peripheral demyelinating neuropathy that met the diagnostic criteria for chronic inflammatory demyelinating polyneuropathy (CIDP), and the cerebrospinal fluid (CSF) examination revealed the remarkably increased protein level. In addition, magnetic resonance imaging of his brain showed a few plaques in white matter, so he was finally diagnosed with combined central and peripheral demyelination (CCPD). Moreover, anti-neurofascin155 (NF155) antibodies assayed in his serum and CSF turned out to be positive. Although he was treated with intravenous immunoglobulin and intravenous methylprednisolone, his symptoms were not ameliorated. However, plasma exchange therapy was apparently effective, and the titer of anti-NF155 antibody was reduced. Recently, the number of case reports of CIDP with CNS lesions has gradually been increasing, while the information about the diagnosis and the treatment responses are not enough. Thus, we reported our case with CCPD who was successfully treated with plasma exchange.