[Symptomatic arachnoid cyst in an elderly patient who developed motor aphasia]

The patient was an 83-year-old woman with a history of breast cancer, distal right radial edge bone fracture, and cervical spine symptoms who had been diagnosed with an arachnoid cyst 9 years previously. She was examined by a nearby doctor, because of an approximately 1-year history of reduced verbal output; she also begun experiencing difficulties with walking. However, she was diagnosed with aging, a history of cervical spondylosis, and the effects of past fractures.At the time of this consultation, she was conscious and lucid, with mild right-sided hemiparesis, was unable to write, and had mild motor aphasia. Head magnetic resonance imaging revealed an arachnoid cyst (longer axis: 10 cm) in the left frontal lobe that did not take up contrast media. There was also a midline shift. The cause of the right hemiparesis and motor aphasia was probably compression of the left frontal lobe by the arachnoid cyst.We performed excision of the cyst wall by craniotomy and placed a cyst-peritoneal shunt under general anesthesia. At approximately one week after surgery, the patient was able to write and her motor aphasia improved. She was discharged 20 days after the operation.It is rare for an arachnoid cyst to increase in size after childhood. In the present case, surgical treatment led to a good outcome in an elderly patient with a symptomatic arachnoid cyst. Arachnoid cysts rarely increase in size. These cysts may become symptomatic in elderly people after lying clinically dormant for a long time.