Case Report of Chiari Formation Affecting the Cauda Equina
In this case report of a 59-year old woman, MRIs are used to study a condition called chiari malformation. In CM, the lower part of the cerebellum protrudes from its normal location in the back of the head.
The word cerebellum means little brain. It is a separate, smaller part of the brain located at the base of the skull just above the cervical spine. In CM, the cerebellum slides down into the cervical or neck portion of the spinal canal.
Sometimes the patient develops a syrinx in the cervical spine.The syrinx is a cyst that fills with cerebrospinal fluid (CSF), expanding and getting longer. The syrinx can extend over several spinal levels. Over time, this condition can destroy the center of the spinal cord.
Syrinx fluid is forced downward with every heart beat. Anything that blocks the free flow of CSF can keep this fluid from moving normally in and out of the head. Pressure builds in the syrinx until it enlarges and ruptures, damaging normal spinal cord tissue and injuring nerve cells.
This patient did not have a syrinx but the MRI showed that the cauda equina in the lower spine was flattened. Cauda equina means horse tail. It is made up of a group of nerves at the end of the spinal cord.
The authors suggest that even though there was no syrinx, abnormal pressure from the cerebrospinal fluid was causing a sandwiching effect. Every time the heart beat a piston effect sent a wave through the CSF, reaching as far down as the cauda equina.
The patient developed symptoms of neck pain and back pain. She had loss of feeling in her arms and legs and increased muscle tone in all four extremities.
Surgery to relieve pressure on the cerebellum and the spinal cord was done. The patient's symptoms went away. The large fluid-filled space around the cauda equina went away. An MRI taken a month later showed a normal positioning of the cauda equina.
Satoru Shimizu, MD, et al. Flat Arrangement of the Cauda Equina in Chiari Malformation. In Journal of Neurosurgery:Spine. April 2007. Vol. 6. No. 4. Pp. 373.