Epidural Indomethacin Alternative in Adult Onset Diabetics
Epidural steroid injections have been advocated for the treatment of degenerative disc disease with radiculopathy1 however, in diabetic patients, steroids have been known to produce hyperglycemia.2 In this study, we determine the effects on blood sugar and pain relief in patients with adult onset diabetes having low back pain with radiculopathy that received either methylprednisolone (MTP) or indomethacin (INM) epidurally. Only patients with recurrent post-laminectomy radiculopathy were included in this study.
Pre- and post-treatment measurements of blood sugar were made in 140 patients between the ages of 32 and 68 years old having recurrent low back pain and signs of unilateral radiculopathy after lumbar laminectomy between January 1999 and March 2003. Previous diagnosis of adult onset diabetes (AOD) had been confirmed in 102 patients. These patients were taking oral antiglycemic medications and were following a regimen of less than 1600 calories/day and were randomly included in groups A,B and C. The other 38 patients (group D) did not have diabetes mellitus. In all subjects, reappearance of degeneration of the same operated—or adjacent—disc and epidural fibrosis were confirmed by magnetic resonance imaging.
The protocol of the study was approved by the Clinical Research Board of both facilities.
After obtaining informed consent, the patients were assigned at random to either group A (38 AOD patients), that received 80mg of MTP; group B (38 AOD patients) that received 1mg of INM; to group C (26 AOD patients) that were given 2mg of INM or to group D (38 non-diabetic patients) given 80mg of MTP. The corticosteroids were diluted in 3 ml of 0.5% bupivicaine. The injections were usually the first epidural injections in a series of 3 or 5 injections.
Measurements of fasting blood sugar were taken in all patients before the epidural injection, and 2, 24, and 48 hours later. Blood samples were taken from the finger tips and processed through the Freestyle Blood Glucose Monitoring System (Thera Sence, Inc. Alameda, CA) that has a 4.8 + 0.9 % coefficient of variation of accuracy.3 No medications were taken by the patients before treatment. The degree and duration of pain relief were determined by the visual analog scale (VAS; scale of 0 to 10) and assessing it before and then two hours after treatment, before the patients were discharged from the facility. Two, 7, and 14 days later, the low back pain levels were obtained by communicating with the patients by telephone. The pain was considered at a “tolerable” level when patients adjudicated a VAS score of less than 4. The results were tabulated and analyzed by the x2 method.
Diabetic patients in groups B, C, having received indomethacin epidurally, had slight to moderately elevated blood glucose levels at fasting. However, for the diabetic patients in group A, having received the corticosteroid methylprednisolone epidurally, the blood sugar levels rose consistently, with averages values being significantly higher (p<0.05), as demonstrated in Table 1.
The control levels of pain, in patients in all groups, was above 7.0 VAS before treatment with the averages for each group shown in Table 1; these values decreased significantly (p<0.05) at two hours and two days after treatment, however only the patients that received MTP 80mg and INM 2mg had average pain reductions below the tolerable level <4,seven days post-treatment. Fourteen days later, the average VAS pain levels, of groups A and C were above 4, but they remained below the average control values. Patients were discharged for home two hours post–injection, soon after the second blood sample was taken. At that time, no significant sensory or motor loss was noted in any patient.
For diabetics, the beneficial anti-inflammatory effect of epidural corticosteroids has been tarnished by some of the complications and side effects2,4 appearing usually after prolonged treatment with usual dosages or after high dosages used in relatively short periods of time.5 Most diabetic patients have a tenuous homeostasis that is difficult to maintain. A decreased adrenocorticotropic hormone (ACTH) and plasma cortisol has been noted 45 minutes after the epidural injection of 40mg of triamcinolone, plus 7 ml of 1% lidocaine— yet the blood sugar remained within normal limits in non-diabetic patients.5 A moderate suppression of the hypothalamic-pituitary-adrenal axis (HPA) has also been documented after epidural triamcinolone, lasting at least two to three weeks, and not responsive when challenged by an insulin-induced hypoglycemic stress.6 In diabetic patients, even a single dose of corticosteroids raises blood sugar and alters the patient’s delicate balance.7
Extremely low levels of steroids can be found in venous blood for up to several weeks after epidural,8 but only minimal trace amounts have been found in CSF.9 It has been assumed that most of the “deposteroids” injected extradurally find their way into circulating plasma and hardly any cross the dura and, instead, act mostly upon the inflamed, degenerated discs and nerve roots outside of the dural sac.10