[A case of chronic myopathy associated with an antibody to signal recognition particle (SRP) following long-term asymptomatic hypercreatinekinasemia].

A 65-year-old man first visited our hospital due to hypercreatinekinasemia (hyperCKemia) (669 IU/l) 12 years ago at age 53. At that time, he had normal muscle strength without other neurological deficits, electromyography (EMG) was normal, and a muscle biopsy obtained from the biceps brachii was intact in routine histochemical studies. These findings led to a diagnosis of idiopathic hyperCKemia that lasted for over a decade. At age 65, the patient became aware of muscle weakness and serum CK was elevated to 4,846 IU/l. Neurological examination revealed very mild atrophy in both thighs, proximal muscle weakness in the left upper and right lower limbs without myalgia, grasping pain, joint pain, and skin lesions. A typical myogenic pattern was detected on EMG exclusively in proximal limb muscles, and fat-suppressed MRI showed high intensity signal areas in adductor magnus muscles. The clinical diagnosis was limb-girdle muscular dystrophy, but MRI findings suggestive of an inflammatory process prompted us to perform muscle biopsy at the rectus femoris. The pathology had characteristic features of necrotizing myopathy containing necrotic and regenerating fibers without prominent inflammatory cell infiltration. Serum anti-signal recognition particle (SRP) antibodies were found to be positive and the final diagnosis was anti-SRP antibody myopathy. Muscle weakness progressed slowly despite therapy with oral corticosteroids. Addition of intravenous high-dose immunoglobulin therapy led to an apparent improvement of muscle weakness in parallel with lowering of the serum CK level. In those who were thought to be idiopathic hyperCKemia or hereditary muscle disorders, potential immunotherapy-effective group does exist. We suggest considering such cases including anti-SRP antibody myopathy during diagnosis, and non-invasive MRI study may be useful to differentiate immunotherapy-effective group from hereditary muscle disorders.

[Orbital apex syndrome without MRI lesion caused by ANCA-associated vasculitis].

A 73-year-old man developed double vision and a progressive loss of visual acuity of the left eye over one week. Examination showed disturbances of the left II, III, IV, and VI cranial nerves, that is, an orbital apex syndrome. A brain MRI showed abnormal T2-high signals in the right maxillary sinus and the left mastoid cells without abnormalities in the left orbital apex and the surroundings. Laboratory examination showed an elevated erythrocyte sedimentation rate and a positive perinuclear anti-neutrophil cytoplasmic antibody (MPO-ANCA). After two courses of methyl-prednisolone pulse treatment, his external ophthalmoplegia fully recovered and he regained his left eye's sight. MPO-ANCA was negative and MRI abnormalities were disappeared after treatment. Two years later, the patient developed upper respiratory symptoms associated with an elevation of MPO-ANCA titer, and rapidly progressive renal failure. Renal biopsy specimen showed fibrinoid necrosis with periarteriolar neutrophil infiltration, which suggested that the patient suffered from ANCA-associated vasculitis probably of Wegener's granulomatosis or microscopic polyarteritis. ANCA-associated vasculitis may present with a focal neurological syndrome such as the orbital apex syndrome without a lesion detectable with MRI.