Diffuse idiopathic skeletal hyperostosis: an unusual cause of difficult intubation.

A case is reported in which anterior osteophytes on the cervical vertebra, in combination with a subglottic stenosis, resulted in distortion of the airway and led to unexpected difficulties during intubation. The osteophytes, associated with the syndrome of diffuse idiopathic skeletal hyperostosis (DISH) were centred at the midcervical level and resulted in anterior displacement of the larynx with an acute angulation of the trachea just below the larynx. This acute angulation, immediately above an unrecognized subglottic stenosis, rendered it impossible to pass all but the smallest endotracheal tube. Diffuse idiopathic skeletal hyperostosis is an ossifying diathesis leading to bone formation in spinal and extraspinal sites, paravertebral osteophyte formation and ligamentous calcification and ossification. Ossification of the anterior longitudinal ligament is common, may be discontinuous, and is often more marked in the thoracolumbar spine than elsewhere. However, isolated and predominant cervical spinal involvement may occur. Diffuse idiopathic skeletal hyperostosis occurs primarily in the elderly population and is often associated with the syndromes of osteoarthritis and ossification of the posterior longitudinal ligament (OPLL). Difficult intubation resulting from anatomical abnormalities of the cervical spine is rare. Although radiological evaluation may be useful in assessing the airway in patients deemed to be at risk for difficult intubation, it cannot be recommended for screening patient populations on a routine basis because of the cost and anticipated extremely low yield. Careful clinical evaluation of the airway before operation and having an approach to the unexpected difficult intubation are emphasized.