Upright MRI in Chiari & connective tissue disorder

You may have seen a recent new items on the use of upright MRI in the diagnosis of hypermobility and cranial settling in Chiari I patients with connective tissue disorders. While this is a very important observation, currently only one case using upright MRI has been published.

In the December 2007 issue of The Journal of Neurosurgery: Spine, Dr. Thomas Millhorat and colleagues performed detailed measurements of the cranio-cervical junction (CCJ) in patients with the Chiari I malformation. Of their database of 2813 CM-I patients, 357 patients had connective tissue disorders that can weaken the ligaments. These patients were taken to the operating room for cranial tong traction performed under sedation. Detailed measurements of the cranio-cervical junction were made before and after traction. The traction test revealed changes in the distances and angles at CCJ in patients with connective tissue disorders.

Toward the end of their study, the authors chose to use standing MRI to measure the CCJ in the supine (lying down) and sitting position. As noted in the images above, they found evidence of cranial settling and gliding of the joints between the skull and cervical 1 vertebrae. The scans show that the tonsils are up in the supine position and droop down into the upper spinal canal in the sitting position.

The findings in this study a very important and the authors are to be congratulated. We look forward to more experience in use of the upright MRI in certain CM-I cases.

Pseudomeningocele after decompression

In the February 10 post, I discussed the development of spinal fluid collection (pseudomeningocele) after surgery for CM-I. I consider a pseudomeningocele to be a clinically significant spinal-fluid collection developing outside of the dura membrane. It may cause pain, compression of the dural patch, crowding of the area of decompression, or spinal fluid leak through the skin.

We calculate the risks of surgery over the previous 100 cases. In the Feb. 10 post, I noted that our incidence of clinically significant fluid collection (pseudomenigocele) was 1% over the previous 100 cases. As of this writing, the risk is 2%.

One of our recent patients hit the top of her head on a shelf 5 weeks after surgery. There was no loss of consciousness, however, the blow was enough to “take her breath away”. Three to 4 days later she developed flu-like symptoms with coughing and gaging and noted return of headache and development of swelling of the wound.

An MRI revealed a pseudomeningocele. She was taken to surgery where spinal fluid was noted to be oozing through a small, few-millimeter, area at the superior suture line. The area was oversewn and a couple of days later  she was discharged home doing well.

John Oro’, MD

chiaritimes@mac.com

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