The Impact of Surgery-Related Muscle Injury on Prevalence and Characteristics of Acute Postcraniotomy Headache - A Prospective Consecutive Case Series.

Background:  The latest third edition of the International Classification of Headache Disorders delineates diagnostic criteria for acute headache attributed to craniotomy (AHAC), but data on possible predisposing factors are sparse. This prospective observational study aims to evaluate the impact of surgery-related muscle incision on the prevalence, severity, and characteristics of AHAC.

Patients And Methods:  Sixty-four consecutive adults (mean age: 54.2 ± 15.2 years; 26 males and 38 females) undergoing cranial neurosurgery for various reasons without preoperative headache were included. After regaining consciousness, all patients reported their average daily headache on a numeric pain rating scale (NRS; range: 0-10), headache characteristics, as well as analgesic consumption from day 1 to 3 after surgery. Three distinct patient cohorts were built with respect to the surgical approach (craniotomy ± muscle incision; burr hole surgery) and group comparisons were performed. Additionally, patients with AHAC ≥ 3 NRS were reevaluated at 7.2 ± 2.3 months following treatment by means of standardized questionnaires to determine the prevalence of persistent headache attributed to craniotomy as well as headache-related disability and quality of life.

Results:  Thirty of 64 (46.9%) patients developed moderate to severe AHAC (NRS ≥ 3) after cranial neurosurgery. There were no significant group differences with regard to age, gender, or general health condition (American Society of Anesthesiologists Physical Status Classification). Craniotomy patients with muscle incision suffered from significantly higher early postoperative mean NRS scores compared with their counterparts without procedure-related muscle injury (3.4 ± 2.3 vs. 2.3 ± 1.9) as well as patients undergoing burr hole surgery (1.2 ± 1.4;  = 0.02). Moreover, the consumption of nonopioid analgesics was almost doubled following muscle-transecting surgery as compared with muscle-preserving procedures ( = 0.03). Young patient age (odds ratio/95% confidence interval for each additional year: 0.93/0.88-0.97) and surgery-related muscle injury (5.23/1.62-19.41) were identified as major risk factors for the development of AHAC ≥ 3 NRS. There was a nonsignificant trend toward higher pain chronification rate as well as headache-related disability after craniotomy with muscle injury.

Conclusion:  Surgery-related muscle damage may be an important predisposing factor for AHAC. Therefore, if a transmuscular approach is unavoidable, the neurosurgeon should be aware of the need for adequately adjusted intra- and postoperative analgesia in these cases.