[Anti-MuSK antibody-positive myasthenia gravis with nephrotic syndrome: a case report].

A 40-year-old man was admitted to our hospital because of dysarthria, difficulty swallowing, double vision and weakness of both upper extremities. There were no detectable anti-AChR antibodies. He was diagnosed with seronegative myasthenia gravis (SNMG) based on a positive edrophonium test and positive waning on repetitive stimulation. Thereafter serological examination detected anti-muscle-specific kinase (MuSK) antibodies and he was diagnosed with anti-MuSK antibody-positive MG. Three years after the onset, the patient developed rapidly progressing respiratory failure and fever. He was diagnosed with aspiration pneumonia caused by swallowing difficulty. He was treated with mechanical ventilation, plasma exchange and antibiotics. Laboratory tests on admission also demonstrated nephrotic syndrome. Renal biopsy specimens showed diffuse thickening of the basement membrane by PAS and PAM stain, and granular immunofluorescent deposits of IgG4 along the glomerular capillary walls. Therefore, he was also diagnosed with membranous nephropathy in addition to anti-MuSK antibody-positive MG. MG is sometimes complicated with nephrotic syndrome, however there has been no report of anti-MuSK-antibody positive MG complicated with nephrotic syndrome. It has been reported that anti-MuSK-antibodies are IgG4 and that membranous nephropathy is suggested to be an IgG4 mediated disease. Our findings suggest that IgG4 may play an important role in the pathogenesis of our patient.

"Prominent ear sign" on diffusion-weighted magnetic resonance imaging in relapsing polychondritis.

Relapsing polychondritis is a rare autoimmune disease characterized by recurrent inflammation of cartilage in multiple sites of the body, including the auricles. Central nervous system involvement appears rare. We encountered a case of relapsing polychondritis with encephalitis that could be diagnosed by the unique appearance of the auricle with signal hyperintensity on diffusion-weighted magnetic resonance imaging.

[A case of myasthenia gravis appearing after thymomectomy: with histopathological investigation].

We report a 64-years old man who had myasthenia gravis (MG) appearing after surgical removal of thymoma. His thymoma was not removed completely due to adhesion with other organs. Histopathologicaly, the thymoma was an invasive and predominantly epithelial type. CD45RO positive cells increased in the thymus. After five months of thymectomy, he received radiation therapy because the remaining tumor grew up slightly. The radiation was effective, and the recurrence of tumor has never been detected after that. However, nine months after the surgery, he noticed ptosis and double vision, and he was diagnosed as MG because of positive serum anti-AchR antibody and positive Tensilon test. He received oral prednisolone, and he has kept a good condition. Previous reports have shown that an extensive thymectomy tends to reduce the incidence of post-operative MG. In our case, the remaining thymoma might increase the risk of MG. And the removed thymus might contain an unknown regulatory factor that could inhibit a development of MG. The risk factor for development of post-operative MG should be investigated in future.

[Bacterial meningitis with Campylobacter fetus manifesting chronic clinical course].

A 43-year-old man with no past history of underlying disease was admitted to an affiliated hospital, complaining of high fever and severe headache. Polynuclear dominant pleocytosis in the cerebrospinal fluid (CSF) suggested bacterial meningitis. He was immediately treated with several antibiotics, then his clinical symptoms improved, although intractable headache relapsed after withdrawal of the initial therapy. Thereafter he consulted our hospital for a second opinion. CSF examination in our hospital demonstrated mononuclear dominant pleocytosis with normal sugar value. However, bacterial culture of the CSF specimen yielded a gram-negative bacillus that was finally identified as a Campylobacter fetus on Skirrow's culture. Treatment with meropenem and other antibiotics improved both the clinical symptoms and CSF findings. Thus, meningitis with a Campylobacter fetus could manifest a chronic and atypical clinical course, careful attention should be paid to establish an early diagnosis.

[A case of neuralgic amyotrophy with antiganglioside antibody].

A 54-year-old-man experienced pain from his left shoulder to his left arm and had difficulty in lifting his arm after a febrile episode. Three weeks after the onset, he was admitted to our hospital. Neurological examination demonstrated weakness and atrophy of the left deltoid muscle. Deep tendon reflexes were normal and no pathological reflexes were elicited. CSF total protein was slightly increased. The occurrence rate of F-waves was decreased in the left upper limb. Magnetic resonance imaging (MRI) study of the cervical cord and brachial plexus with and without Gadolinium infusion showed no abnormalities. Serological study showed that IgM anticytomegalovirus antibody was positive, and that serum IgM anti-GalNAc-GD1a antibody and IgM anti-GM2 antibody were positive. Symptoms were improved after treatment with mecobalamin, 1.5mg/day. This case was considered neuralgic amyotrophy after cytomegalovirus infection. The antiganglioside antibodies may play some role in its pathogenesis.

Ischemic neurophysiological changes of rat sciatic nerve in vitro.

PURPOSE: Patients with ischemic neuropathy always have a progressive reduction in nerve conduction resulting in a transient increase in sensation, such as pain or hyperesthesia. We examined the effect of acute complete ischemia on neurophysiological functions in rat and related electrophysiological changes in ischemic nerve with adenosine 5'-triphosphate (ATP) administration. METHODS: The sciatic nerve of rat was placed directly on 16 parallel 0.5 mm diameter platinum electrodes (5 mm interelectrode distance) in a Perspex chamber bathed in Ringer's solution. The stimulus was applied through the electrode at the rostral end of the nerve, and the action potential recorded along different recording electrodes towards the caudal end of the nerve. Measurements were recorded immediately upon initial nerve placing and then 5, 10, 15, 30, 60, 90 and 120 min after nerve placing. RESULTS: We observed two major components in the monophasic compound action potential of the sciatic nerve of rats (A and B waves). Nerve conduction and amplitude of A and B waves underwent an initial increase followed by a reduction and after ATP administration, the transient augmentation of conduction velocity and amplitude in A and B waves disappeared. The median survival time of peripheral nerve was 60 min. CONCLUSION: At the onset of ischemia, the membrane Na-K pump does not work resulting in an increase of threshold potential in nerve membrane. When ATP levels further decrease, nerve function progressively fails.

The impact of aging on vasa nervorum, nerve blood flow and vasopressin responsiveness.

OBJECTIVE: Aging impacts microvessels in a number of tissue beds. Vasopressin acts as a vasoconstrictor in most blood vessels but may also cause vasodilation. We evaluated the role of aging and vasopressin in the regulation of nerve blood flow (NBF) in rat peripheral nerve. METHODS: We undertook a dose-response study to examine the impact of aging on resting NBF and its vasoreactivity to vasopressin. Nerve blood flow was measured using microelectrode hydrogen polarography. Arginine-vasopressin was administered both intra-arterially and topically. RESULTS: In young adult rats (two months old) topical epineurial application of arginine-vasopressin produced a concentration-dependent reduction of NBF (ED50 = 3.8 x 10(-5) mol/L). Intra-arterial arginine-vasopressin also reduced NBF. Nerve blood flow was lower in aged rats (12 months old) and less responsive to topically applied vasopressin. The aging group had significantly higher concentrations of vasopressin in plasma than did the younger group. CONCLUSIONS: The results suggest that vasopressin constricts vessels in peripheral nerve and that there is an age related decline in the vasoconstrictive response to vasopressin. There may be a reduction in receptor sensitivity in vascular smooth muscle cells in peripheral nerve with increasing age.