The X-files: May 2009

Marshall Deltoff
April 30, 2009
Written by Marshall Deltoff

My sincere thanks to Dr. Ernie Perry of Toronto for sharing this case.

This 40-year-old female presented with headaches and neck pain.  She had been previously diagnosed with psoriatic arthritis.

The neutral lateral radiograph demonstrated an atlantodental interspace (ADI) width of 5 mm (Figure A).

Let’s review some of the etiologies for increased ADI:

First and foremost, make sure that the film was taken at a 72 inch FFD; if taken at 40 inches, the ADI, like everything else on the film, will naturally be magnified, and the accepted 3 mm normal limit cannot apply. That said, a variety of disorders may alter the interspace.

Of course, degenerative joint disease would contribute to a decreased space.  The more frequent causes of a widened space include trauma, occipitalization, Down’s syndrome, certain pharyngeal infections, and the various inflammatory arthropathies such as ankylosing spondylitis, rheumatoid arthritis, psoriatic arthritis and Reiter’s syndrome. Flexion/extension views are indicated when a widened space is noted on the neutral lateral film, in order to evaluate any upper cervical complex instability. MRI examination will clearly demonstrate transverse ligament status and integrity.•

A 1983 CMCC graduate, Dr. Marshall Deltoff completed his radiology residency at Los Angeles College of Chiropractic. He is a past radiology department chairman and residency coordinator at CMCC, and he initiated the radiology curriculum at UQTR. Dr. Deltoff has lectured throughout North America, and is co-author, along with Dr. Peter Kogon, DACBR, of the radiology text “The Portable Skeletal X-ray Library” published by Mosby-Yearbook of St. Louis. Dr. Deltoff can be reached at: Images Radiology Consultants, 16 York Mills Road, Toronto, Ont.  M2P 2E5 Tel: (416) 512-2225   Fax: (416) 512-2226   e-mail: This e-mail address is being protected from spambots. You need JavaScript enabled to view it

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