[A case of small epidermoid cyst in cauda equina with manifest regional hypesthesia].

This report concerns the 22-year-old female who has been suffering the paresthesia in the left buttock and thigh for three months. Neurological examination revealed nothing other than hypesthesia and hypalgesia which distributed in the third, fourth and fifth segments of left sacral region with the loss of anal reflex. Pain had not been noticed until when she came to our clinic. Myelography and MRI showed small irregular round mass occupying a third of the spinal canal behind the body of fourth lumbar spine. In the axial view of MRI, the mass was enhanced by the gadolinium (Gd) except for the small portion of its center. She underwent the surgical treatment which revealed the tumor entangling four nerves of cauda equina in its center as imaged in MRI. The tumor was epidermoid cyst which presumably caused the chemical meningitis and involved those nerves. That resulted in the sensory disturbance in the left sacral region, although the tumor was not large enough to compress the nerves.