Headache relief after anterior cervical discectomy: post hoc analysis of a randomized investigational device exemption trial: clinical article

Abstract

Object: The authors analyzed headache relief after anterior cervical discectomy. Headache may be relieved after anterior cervical discectomy, but the mechanism is unknown. If headaches were directly referred from upper cervical pathology, more headache relief would be expected from surgery performed at higher cervical levels. If spinal kinesthetics were the mechanism, then headache relief may differ between arthroplasty and fusion. Headache relief after anterior cervical discectomy was quantified by the operated disc level and by the method of operation (arthroplasty vs arthrodesis).

Methods: The authors performed a post hoc analysis of an artificial disc trial. Data on headache pain were extracted from the Neck Disability Index (NDI) questionnaire.

Results: A total of 260 patients underwent single-level arthroplasty or arthodesis. Preoperatively, 52% reported NDI headache scores of 3 or greater, compared with only 13%-17% postoperatively. The model-based mean NDI headache score at baseline was 2.5 (95% CI 2.3-2.7) and was reduced by 1.3 points after surgery (95% CI 1.2-1.4, p < 0.001). Higher cervical levels were associated with a greater degree of preoperative headache, but there was no association with headache relief. There was no significant difference in headache relief between arthroplasty and arthrodesis.

Conclusions: Most patients with symptomatic cervical spondylosis have headache as a preoperative symptom (88%). Anterior cervical discectomy with both arthroplasty and arthrodesis is associated with a durable decrease in headache. Headache relief is not related to the level of operation. The mechanism for headache reduction remains unclear.

Keywords: IDE = investigational device exemption; IHS = International Headache Society; NDI = Neck Disability Index; cervical; cervicogenic; headache; spine; spondylosis.

Figures

Fig. 1

The effect of surgery type (artificial disc vs fusion) on headache relief. The pre- and postoperative NDI headache scores were 2.5 and 1.1, respectively, for the artificial disc group and 2.4 and 1.2, respectively, for the fusion group. There was no significant difference between the groups (p = 0.56).

Fig. 2

The effect of the operated level on headache relief. The highest levels (C3–4 and C4–5) were combined for analysis, since the number of operations at these levels was low (5 and 13, respectively). The pre- and postoperative NDI headache scores, respectively, were 2.8 and 1.6 for levels C3–4/C4–5, 2.6 and 1.2 for C5–6, and 2.1 and 0.9 for C6–7. Higher levels (those more proximal to the head) were associated with greater preoperative pain. There was no difference, however, in degree of postoperative pain relief as a function of what level was surgically treated (p = 0.45 for quantitative approach, p = 0.38 overall for categorical approach).

Fig. 3

The preservation of headache relief after surgery over time in all patients up to 2 years postoperatively. Postoperative headache NDI scores at baseline (BL), 6 weeks (6W), 12 months (12M), and 24 months (24M) were 2.48, 1.07, 1.26, and 1.24, respectively. We found a statistically significant trend for very gradual worsening of pain level of 0.002 NDI headache points per week (p = 0.018), amounting to a change of just a tenth of a point worse per year. The 2nd year showed an attenuation of a significant portion of the pain relief from the first 6 weeks to 6 months after surgery, but with most of the improvement retained.