Rheumatologic disorders – Questions 1. Is rheumatoid arthritis (RA) just a disease of the joints and adjacent connective tissue?
2. What are some of the clinical manifestations of RA?
3. What are some airway abnormalities that can occur in patients with rheumatoid arthritis?
4. Why might the normal mouth opening be decreased in patients with rheumatoid arthritis?
5. What occurs to the developing mandible in patients with juvenile rheumatoid arthritis that makes it more difficult to intubate the trachea in this patient population?
6. What are some of the clinical manifestations of cricoarytenoid arthritis?
7. Can neck movement in patients with RA result in cervical spine injury? What is the clinical implication of this?
8. What percent of patients with RA have involvement of their cervical spine?
9. What are three abnormal movements of the cervical spine that may be manifest in patients with rheumatoid arthritis?
10. What is atlantoaxial subluxation?
11. What pathology in RA patients can lead to atlantoaxial subluxation?
12. How is the degree of atlantoaxial subluxation measured? What is this measurement called?
13. What test can be used to determine the atlas-dens interval?
14. What degree of motion between the atlas and dens, or at what atlas-dens interval, is the patient considered to be at risk for spinal cord injury?
15. In the case of pure transverse axial ligament disruption, does flexion or extension increase the atlas-dens interval?
16. If a patient is asymptomatic with neck flexion and extension preoperatively can the anesthesiologist be reassured of an atlas-dens interval of less than 4mm?
17. What is subaxial subluxation? What is its clinical significance?
18. What is superior migration of the odontoid? What are the potential clinical manifestations?
19. What is the surgical treatment for superior migration of the odontoid?
20. What effect does rheumatoid arthritis have on the trachea?
Rheumatologic disorders – Answers 1. RA is a chronic inflammatory disease, which initially destroys joints and adjacent connective tissue and then progresses to a systemic disease affecting major organ systems. (499, Figure 32-1)
2. Systemic manifestations of RA are widespread. They may include pulmonary involvement with interstitial fibrosis and cysts with honeycombing, gastritis and ulcers from aspirin and other analgesics, neuropathy, nephropathy, muscle wasting, vasculitis, and anemia. Ultimately the anatomy of the airway is damaged and altered in patients with rheumatoid arthritis. (499, Figure 32-1)
3. Some airway abnormalities that can occur in patients with rheumatoid arthritis include decreased mouth opening, a hypoplastic mandible, cricoarytenoid arthritis, and cervical spine abnormalities. (499-500)
4. Normal mouth opening may be decreased in patients with rheumatoid arthritis as a result of temporomandibular arthritis. (499)
5. The patient with juvenile rheumatoid arthritis often has a hypoplastic mandible as a result of early fusion. This results in the noticeable overbite in some patients with RA. (499)
6. As with other joints, the cricoarytenoid joint may be affected by rheumatoid arthritis. Cricoarytenoid arthritis may result in shortness of breath and snoring. RA patients have been misdiagnosed as having sleep apnea when in fact it they have cricoarytenoid arthritis. Patients with cricoarytenoid arthritis may present with stridor on inspiration. This may present in the postanesthesia care unit (PACU) while the patient is recovering from anesthesia. Acute subluxation of the cricoarytenoid joint, as a result of tracheal intubation, can cause stridor as well, and it is not responsive to racemic epinephrine. (500)
7. Yes, movement of the neck in patients with RA can result in cervical spine injury. The patient must be carefully evaluated for both the complexity and the risk of endotracheal intubation because of difficulty in visualizing the airway as a result of the anatomic changes that occur. Normal endotracheal intubation maneuvers with neck movement may result in an increased risk of cervical spine injury due to destruction of the bones and ligaments of the cervical spine. These can place the cervical spinal cord at risk. Many cervical spine abnormalities may occur in patients with RA. (499)
8. The cervical spine is affected in up to 80% of patients with RA. (500)
9. Three abnormal movements of the cervical spine that may be manifest in patients with rheumatoid arthritis include atlantoaxial subluxation, subaxial subluxation, and superior migration of the odontoid. (500, Figure 32-2).
10. Atlantoaxial subluxation is the abnormal movement of the C1 cervical vertebra (the atlas) on C2 (the axis). (500)
11. Normally, the transverse axial ligament holds the odontoid process, (also referred to as the dens), which is the superior projection of the vertebra of C2, in place directly behind the anterior arch of C1. With destruction of the transverse axial ligament by RA, movement of the odontoid process is no longer restricted. As the neck is flexed and extended, the C1 vertebra can sublux on the C2 vertebra. This can result in impingement of the spinal cord, placing it at risk for damage. (500-501, Figure 32-3)
12. Subluxation of C1 on C2, referred to as atlantoaxial subluxation, can be quantified by a measuring the distance between the back of the anterior arch of C1 and the front of the dens or odontoid. This distance is referred to as the atlas-dens interval. (501)
13. Flexion and extension radiographs of the cervical spine are obtained to determine the distance between the atlas and dens, or the atlas-dens interval, and thus the degree of subluxation. (501, Figure 32-4)
14. If the atlas-dens interval is 4mm or more atlantoaxial instability is present, the amount of subluxation is considered significant, and the patient is considered to be at risk for spinal cord injury. (501)
15. In a situation in which the transverse axial ligament is disrupted, extension of the neck minimizes the atlas-dens interval and increases the safe area for the spinal cord. Conversely, flexion of the neck increases the atlas-dens interval and decreases the safe area for the spinal cord, making flexion a more frequent risk position. Still, rheumatoid arthritis affects more than just the transverse axial ligament; therefore, all neck movements in patients with rheumatoid arthritis have to be evaluated carefully as extension of the neck can also lead to problems. (501, Figure 32-5)
16. Patients with rheumatoid arthritis can be asymptomatic with neck flexion and extension preoperatively while awake, and still have an atlas-dens interval of greater than 4mm and be at risk for cervical spine injury. These patients are able to compensate for their cervical spine instability through local muscle. Once anesthetized and the muscles are relaxed, atlantoaxial subluxation may occur. Therefore the anesthesiologist should not be falsely reassured by asymptomatic flexion and extension in the awake patient. (502)
17. Subaxial subluxation is the subluxation of 15% or more of one cervical vertebra on another at any level below C2. Subaxial subluxation most commonly occurs at the C5-C6 level. Patients with subaxial subluxation are at risk for spinal cord impingement with neck movement. Minimal neck movement is recommended in these patients. (502)
18. Superior migration of the odontoid is a condition where an intact odontoid process projects up through the foramen magnum and into the skull. This occurs because of inflammation and bone destruction that results in cervical spine collapse with sparing of the odontoid process. This can occur because not all areas of the cervical spine are equally affected in any given patient. If the odontoid is spared, the intact odontoid can impinge on the brainstem and patients may suffer neurologic symptoms including quadriparesis or paralysis. (502, Figure 32-6)
19. Surgical treatment for superior migration of the odontoid involves removal of the odontoid to decompress the spinal cord and brainstem. A complicated surgical procedure, referred to as a transoral odontoidectomy, may be performed to accomplish this and involves an incision in the posterior pharyngeal wall, followed by removal of the arch of C1 and then removal of the odontoid and pannus, to relieve neurologic symptoms. With completion of the transoral portion of the procedure, the cervical spine is very unstable, necessitating a posterior spinal fusion. (503)
20. Although the cervical spine is affected by rheumatoid arthritis and may collapse from bone destruction, the trachea is usually spared. This results in the trachea twisting in a characteristic manner as the cervical spine collapses, only serving to increase the difficulty of intubating the trachea of these patients. Tracheal intubation aids such as a fiber optic bronchoscope, Glidescope, Airtraq, or intubating LMA should be available for assistance in endotracheal intubation of these patients should it be required. (503)