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PEDIATRIC ANESTHESIA

Atlantoaxial Rotatory Subluxation After a Pediatric Tonsillectomy

Department of Anesthesiology, Kaiser Permanente Medical Center, Sacramento, California

Address correspondence to Kevin R. Dasen, MD, Department of Anesthesiology, Kaiser Permanente Medical Center, 2025 Moross, Sacramento, CA 95825. Address e-mail to kdasen{at}aol.com

	Introduction

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Atlantoaxial subluxation has been documented in the anesthetic literature in association with trisomy-21, rheumatoid arthritis, and ankylosing spondylitis. Subluxation may be designated as either rotational or nonrotational by radiographic criteria. In addition, the subluxation of C1 on C2 may be anterior, as is seen with transverse ligament laxity, or posterior, as occurs with dens fractures. Case reports in the anesthetic literature have discussed neurologic injuries after airway manipulation (1,2). Such injuries are usually associated with bone or ligament abnormalities.

This case report depicts a relatively healthy 7-yr-old boy who was diagnosed with a postoperative atlantoaxial rotatory subluxation after a tonsillectomy and adenoidectomy (T&A). Although there was never any indication of neurologic injury in this case, the possibility of airway management as a contributing cause for atlantoaxial subluxation was considered. A search of the anesthetic literature revealed one letter, which briefly addressed atlantoaxial subluxation with torticollis, and one non-English language case report on the subject (3,4). This case report describes Grisel’s syndrome, an atlantoaxial rotatory subluxation after parapharyngeal inflammation, and examines the effects of airway management on the atlantoaxial joint.

	Case Report

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The patient was an obese, 40-kg, 7-yr-old boy, who had a history of tonsillar hypertrophy, snoring, and recurrent tonsillitis. Previously, he had been treated with oral antibiotics and was scheduled for T&A. Physical examination revealed a Mallampati class 2 airway showing soft palate, faucial pillars, and enlarged tonsils. Range of motion in his neck was normal, as were vital signs. Routine monitors were applied in the operating room, and general anesthesia was induced with sevoflurane. Mask ventilation was easily performed. An IV catheter was placed, and mivacurium 0.2 mg/kg IV was administered. The patient was uneventfully tracheally intubated with a 5.0 (internal diameter) cuffed oral endotracheal tube using a Miller 2 blade for direct laryngoscopy. A rolled towel was placed under the shoulders to facilitate surgical exposure with midline head and neck extension. After surgery, once appropriately responsive, the patient was suctioned, tracheally extubated, and placed on his side for transport. Fentanyl (2 µg/kg IV) was given during the perioperative period. He was discharged home without musculoskeletal or neurologic symptoms.

A telephone call the following day found the patient without complaint. Subsequently, he presented to the emergency room on the fourth postoperative day with "cock robin" head positioning, a painful neck, left torticollis, hoarseness, cough, uvular edema, and a low-grade fever (37.6°C). Physical examination revealed spasm of the paraspinous muscles and diffuse neck tenderness during palpation. His symptoms began approximately 24 h postoperatively.

Neurosurgical consultation was obtained, and atlantoaxial rotatory subluxation was diagnosed after radiographic examinations were reviewed. Lateral cervical spine radiographs showed an increased atlas-dens interval (ADI) of 5 mm (Fig. 1). An open-mouth view showed the dens eccentric to the left. A computerized tomography (CT) scan showed the spinous process of C1 to be to the left of midline, while the spinous process of C2 was midline. The chin was to the right of midline. The consulting neurosurgeon felt that parapharyngeal inflammation led to spasm of the deep cervical musculature, causing atlantoaxial rotatory subluxation. Atlantoaxial rotatory subluxation associated with inflammation and torticollis in children has been described as Grisel’s syndrome (5). Treatment recommendations from the consulting neurosurgeon to reduce and stabilize the atlantoaxial joint included wearing a hard cervical collar for 3 mo. Amoxicillin and acetaminophen with codeine were prescribed for infection and neck pain. Repeat cervical spine radiographs taken the following day showed a decreased ADI (3 mm). Radiographs taken 13 days postoperatively showed resolution of the rotatory subluxation. He regained full range of motion in his neck and had a normal neurological examination on follow-up.

View larger version (93K): [in this window] [in a new window]   Figure 1. Lateral cervical spine radiograph. A, increased atlas-dens interval of 5 mm.

	Discussion

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In 1930, Grisel described a syndrome of torticollis with atlantoaxial rotational deformity occurring in children after nasopharyngeal infection (5,6). Septic exudates found in the oropharynx are thought to drain into the periodontoidal plexus and epidural veins via the pharyngovertebral venous plexus (7). Resultant inflammation attenuates the synovial capsules and transverse ligament, leading to an increased ADI from ligamentous laxity. The transverse ligament is the primary stabilizer of the atlantoaxial joint and transverses posterior to the dens to prevent excessive anterior displacement of C1 in relation to C2. The increased incidence of rotatory subluxation found in children, relative to adults, may be related anatomically to their greater dens-facet angle of C2 and the presence of meniscus-like synovial folds in the lateral atlantoaxial joints (8). Early diagnosis is imperative, as the chance of permanent disability, such as facial asymmetry and permanent torticollis, increases with a delay in diagnosis. If a rotatory subluxation has been present for more than a month, traction may be unsuccessful, and posterior arthrodesis will be needed to normalize the torticollis (9).

Wilson et al. (10) examined 62 reported cases of atlantoaxial rotatory subluxation from 1830 to 1985. Forty cases (65%) were in children ages 5 to 12 years, and 14 of the cases (23%) occurred postoperatively. Of the postoperative cases, five followed T&A, and seven followed mastoidectomies. Operations that use extreme head rotation for prolonged periods of time, such as mastoidectomies, may involve an increased risk of rotational subluxation. Under general anesthesia, normal protective cervical muscular tone is decreased, and head rotation exceeding 65° may involve complete bilateral C1-C2 facet dislocation with ligamentous disruption (11). Although the present case did not involve head rotation, minimizing intraoperative head rotation is important in preventing iatrogenic atlantoaxial rotatory subluxation (12). In addition to head rotation, spasm of deep cervical musculature secondary to inflammation may contribute to postoperative atlantoaxial rotatory subluxation (5). The consulting neurosurgeon considered this muscle spasm a likely mechanism contributing to our patient’s atlantoaxial rotatory subluxation.

There is controversy regarding the best radiographic technique for diagnosis of atlantoaxial rotatory subluxation. Commonly, lateral cervical spine, posteroanterior, and open-mouth films have been taken (10). However, axial CT scans, cineroentgenography, and dynamic CT scans have also been used (5). A lateral cervical spine film with an ADI greater than 4 mm in children is suggestive of atlantoaxial subluxation (13). Sudeck’s sign is indicative of atlantoaxial rotation when the chin and the spinous process of C2 are on the same side of midline (10). Even when the head and neck are placed in a neutral position, the C1-C2 rotation remains unchanged.

Numerous investigators have studied motion of the cervical spine during airway management. Direct laryngoscopy and intubation have been shown to extend the atlantoaxial joint between 9 and 25 degrees in adults (14,15). Chin lift and jaw thrust maneuvers on cadavers were found to have similar changes in both angulation and distraction in the face of stable and unstable atlantoaxial joints, when compared with oral intubation (16). These studies demonstrated that motion of the upper cervical spine was predominantly in the direction of extension during airway management. It should be noted that these studies used nonuniform methodologies on adult, not pediatric, patients. However, extension at the atlantoaxial joint will decrease, not increase, the ADI (17).

Given the mechanical impossibility of increasing the ADI with head extension and the 24-hour delay in symptoms, it would be reasonable to exclude airway manipulation as a probable cause of the patient’s atlantoaxial rotatory subluxation. However, conclusive proof to eliminate airway manipulation as the cause (such as that which would be obtained through the use of continuous cervical cinefluoroscopy) was not obtained.

Head and neck manipulations that increase the ADI, such as head flexion, could contribute to a postoperative atlantoaxial rotatory subluxation. For example, this may occur during surgical positioning or while attempting to intubate a difficult airway. Our patient was tracheally intubated on the first attempt without complications. However, manipulation of the cervical spine during positioning for the T&A could have caused an increased ADI. As the head was maintained in extension, however, positioning was probably not a source of an increased ADI.

In summary, Grisel’s syndrome is an atlantoaxial rotatory subluxation associated with torticollis and "cock robin" head positioning in children. It is thought to involve transverse ligament laxity and spasm of the deep cervical musculature (not airway management), which is, in turn, secondary to parapharyngeal infection. Minimizing intraoperative head rotation may help prevent postoperative atlantoaxial rotatory subluxation, and early diagnosis, of less than one month, usually allows this syndrome to be successfully treated without surgery.

	References

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