RHEUMATOID-ARTHRITIS OF THE CERVICAL-SPINE - A LONG-TERM ANALYSIS WITH PREDICTORS OF PARALYSIS AND RECOVERY

We analyzed the cases of seventy-three patients who were managed over a twenty-year period for rheumatoid involvement of the cervical spine and were followed for a minimum of two years, with an average follow-u p of seven years. A neurological deficit did not develop in thirty-one patients (Ranawat et al. Class I) and paralysis developed in the rema ining forty-two patients: Class II in eleven and Class III in thirty-o ne. Of the forty-two patients in whom paralysis developed, thirty-rive had operative stabilization. Seven patients were managed with a soft cervical collar because they refused or were medically unable to have the operation; all of them had an increase in the severity of the para lysis. The posterior atlanto-odontoid interval and the diameter of the subaxial sagittal canal measured on the cervical radiographs demonstr ated statistically significant correlations with the presence and seve rity of paralysis. All of the patients who had a Class-III neurologica l deficit had a posterior atlanto-odontoid interval or diameter of the subaxial canal that was less than fourteen millimeters. In contrast, the anterior atlanto-odontoid interval, which has traditionally been r eported, did not correlate with paralysis. The prognosis for neurologi cal recovery following the operation was not affected by the duration of the paralysis but was influenced by the severity of the paralysis a t the time of the operation. The most important predictor of the poten tial for neurological recovery after the operation was the preoperativ e posterior atlanto-odontoid interval. In patients who had paralysis d ue to atlantoaxial subluxation, no recovery occurred if the posterior atlanto-odontoid interval was less than ten millimeters, whereas recov ery of at least one neurological class always occurred when the poster ior atlanto-odontoid interval was at least ten millimeters. If basilar invagination was superimposed, clinically important neurological reco very occurred only when the posterior atlanto-odontoid interval was at least thirteen millimeters. All patients who had paralysis and a post erior atlanto-odontoid interval or diameter of the subaxial canal of f ourteen millimeters had complete motor recovery after the operation. I n this series, although only patients who had a neurological deficit w ere operated on, we observed the range of the posterior atlanto-odonto id interval that was associated with poor or no recovery after the ope ration, and we identified the safe range on the basis of the patients in whom paralysis did not develop. Therefore, to minimize the potentia l risk of the development of irreversible paralysis, we recommend oper ative stabilization of the rheumatoid cervical spine, in the presence or absence of a neurological deficit, for patients who have atlanto-ax ial subluxation and a posterior atlanto-odontoid interval of fourteen millimeters or less, patients who have atlanto-axial subluxation and a t least rive millimeters of basilar invagination, and patients who hav e subaxial subluxation and a sagittal diameter of the spinal canal of fourteen millimeters or less.