[A surgical fenestration of an arachnoid cyst in the cerebellomedullary cistern].

Arachnoid cysts originating from the cerebellomedullary cistern are very rare, and their indications for surgical treatment remain controversial. A 41-year-old man with a cystic lesion in the left cerebellomedullary cistern presented with sudden perspiration, palpitations, and vertigo. Subsequently, he complained of numbness of the left extremities and a dull headache. Otolaryngological evaluation revealed no abnormality. Physical examination on admission showed no neurological manifestations, except for left sensory disturbance. MRI revealed a cyst in the left cerebellomedullary cistern. Radiological examination did not reveal direct compression of the brain stem by the cyst, but the left cerebellum was compressed by the cyst. The patient underwent surgical fenestration of the arachnoid cyst via the midline suboccipital approach. The symptoms immediately disappeared after surgery. Patients with an arachnoid cyst in the cerebellomedullary cistern usually present lower cranial nerve dysfunction as a symptom. In our case, there was no cranial nerve dysfunction, but anatomically unexplainable symptoms, such as perspiration, palpitations, dizziness, and numbness of the left limbs, were observed. In conclusion, even if a patient with an arachnoid cyst in the posterior cranial fossa presents unexplainable symptoms, surgical intervention, including fenestration, is one of the therapeutic options.

Analysis of C9orf72 repeat expansion in 563 Japanese patients with amyotrophic lateral sclerosis.

Recently, a hexanucleotide repeat expansion in C9orf72 was identified as the most common cause of both sporadic and familial amyotrophic lateral sclerosis (ALS) and frontotemporal dementia in Western populations. We analyzed 563 Japanese patients with ALS (552 sporadic and 11 familial) using fluorescent fragment-length analysis of C9orf72 and repeat-primed polymerase chain reaction analysis. Haplotype analysis was performed for 42 single nucleotide polymorphisms in patients with C9orf72 repeat expansion. C9orf72 repeat expansion was found in 2 patients with sporadic ALS (2/552 = 0.4%) and no patients with familial ALS (0/11 = 0%). In the probands' families, 1 primary progressive aphasia patient and 1 asymptomatic 76-year-old individual exhibited C9orf72 repeat expansion. All of the patients with the C9orf72 repeat expansion carried the 20-single nucleotide polymorphism consensus risk haplotype. The frequency of the C9orf72 repeat expansion among Japanese patients is much lower than in Western populations. The existence of a 76-year-old asymptomatic carrier supported the notion of incomplete penetrance. The C9orf72 mutation should be analyzed in sporadic ALS patients after determining their family histories not only of frontotemporal dementia but also of primary progressive aphasia.