Diffuse idiopathic skeletal hyperostosis (DISH) is a common disease of the aging population, characterized by multiple axial and extraaxial involvement. 1When the spine is affected, calcification and ossification along the anterior surface of several vertebrae can occur. 2Reports that DISH of the cervical spine impairs management of the upper airway during anesthesia are rare. The authors describe a case of progressive dysphagia, new-onset obstructive sleep apnea, and difficult awake fiberoptic intubation due to anterior cervical osteophyte disease from DISH.
A 55-yr-old man 1(height, 177 cm; weight, 95 kg) was admitted with a 1-month history of progressive weakness and numbness of the lower extremities. His medical history was significant for controlled hypertension, progressive dysphagia for solids and liquids, and new-onset obstructive sleep apnea, consequently requiring continuous positive airway pressure of 12 cm H2O. A recent sleep study showed a baseline apneahypopnea index of 42 (severe obstructive sleep apnea), with marked improvement to 4 when a continuous positive airway pressure of 11 cm H2O without oxygen supplementation was instituted.
Preoperative cervical magnetic resonance imaging showed neural foraminal narrowing from C3–C4 to C6–C7, mild canal stenosis, and thecal compression at C6–C7. The patient was scheduled for C3–C7 laminectomies and fusion. Preoperative airway examination showed a two-finger breadth mouth opening, a 5-cm mentohyoid distance, and a Mallampati score of II. Neck flexion resulted in dyspnea, whereas neck extension was significantly limited secondary to severe pain. Awake fiberoptic intubation and positioning were planned because of findings on airway examination and the presence of early cervical myelopathy.
Sufentanil and midazolam were used for sedation because of marked preoperative anxiety. These agents were carefully titrated until the patient was somnolent but easily arousable and able to follow commands. His respiratory rate was maintained at greater than 10 breaths/min with an oxygen saturation greater than 95% on room air. Glycopyrrolate was administered preoperatively to decrease oral secretions; atropine was not used because of concerns of resultant tachycardia. Local anesthesia of the upper airway was accomplished with topical lidocaine and superior laryngeal nerve, glossopharyngeal nerve, and transtracheal blocks. Despite multiple attempts at oral fiberoptic laryngoscopy using the Williams airway, neither the epiglottis nor the vocal cords could be identified because of a combination of residual secretions and the unexpected presence of a large soft tissue mass extending from the posterior pharyngeal wall to the base of the tongue. The presence of a large anterior mass had not been detected during evaluation of the preoperative cervical radiographs. Direct laryngoscopy and light wand intubation was attempted without success. After multiple attempts at intubation, the decision was made to postpone the procedure, and the patient was admitted to the intensive care unit for observation because of concerns of airway edema.
The cervical radiographs were reevaluated. A large anterior osteophyte extending from C2 to C6 —more pronounced at the C3–C4 level—was considered the culprit. The diagnosis of DISH was made (fig. 1).
The patient returned to the operating room a week later. He was premedicated with glycopyrrolate and atropine. After confirming the lack of oral secretions, local anesthesia of the upper airway was accomplished in a similar fashion. It was also decided to provide only minimal sedation to preserve full cooperation from the patient. Fiber-optic laryngoscopy confirmed the soft tissue mass. The epiglottis was noted to be deviated to the left of the midline, and the vocal cords could only be visualized briefly with deep inspiration. Intubation was difficult but accomplished successfully with a 7.0 endotracheal tube lubricated with lidocaine gel. Surgery proceeded uneventfully, and the postoperative course was uncomplicated.
The patient returned 2 months later for anterior osteophytectomy. Awake fiberoptic intubation with minimal sedation and patient cooperation was performed successfully. Postoperatively, the patient had resolution of his dysphagia and improvement in his obstructive sleep apnea and continuous positive airway pressure requirements. Postoperative sleep studies were not obtained.
Degenerative disease of the cervical spine is relatively common after the age of 40 yr and affects a significant number of patients after the seventh decade of life. The three most common causes of cervical osteophytosis are ankylosing spondylitis, DISH, and degenerative disc disease.
The axial distribution of DISH primarily involves the thoracic spine, followed in frequency by the lumbar and cervical spine. When the cervical spine is involved, coexisting ossification of the posterior longitudinal ligament is detected in approximately 50% of patients and may be responsible for spinal canal narrowing and neurologic deficits. 3Cervical spine alteration is most common between the fourth and seventh vertebral bodies.
Extensive cervical hyperostosis that can be associated with DISH may result in symptoms related to compression, distortion, or both of the aerodigestive tract, including dysphagia, stridor, dyspnea, and obstructive sleep apnea. 4–7Reports of difficult intubation are surprisingly rare. The presence of an enlarged cervical osteophyte may lead to edema of the laryngeal inlet, aggravating the mechanical obstruction. 8
Our patient’s cervical radiograph shows the presence of a large contiguous osteophyte involving the C2–C6 area. The apex of the osteophyte lies adjacent to the epiglottis, and the airway seems markedly narrow at this point, thus making fiberoptic visualization of the larynx and placement of the endotracheal tube difficult. Deep sedation during the initial fiberoptic intubation attempt prevented the patient from inspiring maximally, which was needed to optimally locate the laryngeal inlet. With subsequent fiberoptic intubation attempts, a lighter level of sedation was chosen, and the patient was instructed to inspire deeply during advancement of the fiberoptic scope, beyond the area of critical narrowing. In addition, more aggressive use of antisialogogue agents facilitated subsequent attempts. In patients with obstructive sleep apnea, adipose tissue deposits in the lateral walls of the pharynx, which is the most important site of collapse during deep sleep and when central nervous system depressants are used. 9With deep sleep or sedation, upper airway muscle tone decreases and upper airway resistance increases, resulting in generation of subatmospheric pressure in the pharynx and ultimate pharyngeal collapse. 9
The presence of excessively large cervical osteophytes, particularly those located adjacent to areas of normal esophageal fixation, may also impair swallowing. 10–12There is also an increased risk for aspiration pneumonitis because of the altered anatomy of the hypopharynx.
Cervical dysphagia may improve with conservative therapy; however, the definitive management is surgical resection of the osteophyte. Obstructive sleep apnea has been described when large cervical osteophytes are present in combination with relaxation of the hypopharyngeal musculature in the supine position. 13Continuous positive airway pressure devices relieve the obstruction caused by these large osteophytes during inspiration.
The presence of dysphagia, dyspnea, or sleep apnea, as in our patient, should alert the clinician to possible upper airway obstruction from large anterior cervical osteophytes. This mechanical distortion may complicate both direct laryngoscopy and intubation. Thorough peri-operative preparation and radiographic imaging is necessary to manage this condition successfully.