Outcomes After Surgery for Degenerative Cervical Radiculopathy in Patients with Concurrent Headache

Surgery for degenerative cervical radiculopathy (DCR) is one of the most common causes of neck surgery. The typical surgical indication is radicular pain (arm pain) caused by nerve impingement. However, many patients also report varying degrees of pain in the neck and head. This headache, often referred to as cervicogenic headache (CEH), is believed to result from the convergence of trigeminal afferents and the upper three cervical spinal nerves in structures such as facet joints, ligaments, cervical muscles, intervertebral and nerve roots.

The diagnostic criteria used to distinguish CEH from the other types of headaches are based on low to moderate evidence and can be challenging due to their similar clinical presentations. Nevertheless, headache disorders are a common cause of disability and many patients undergoing surgery for DCR report headache. However, prior reports assessing headache in patients surgically treated for DCR are limited by small sample sizes, inconsistent inclusion criteria and outcome measures. Consequently, there is limited understanding about the frequency of DCR associated headache and whether these patients experience meaningful improvements in their headache following surgical treatment.

The aims of this study are to assess 1) the frequency of DCR associated headache in patients operated for DCR, 2) the minimal clinical important change for NRS headache 3) if DCR associated headache is an independent prognostic factor for neck pain-related disability and 4) if patients experience improvement in their headache 12 months after surgery for DCR.

Hypothesis:

Our null hypothesis is that DCR patients with and without concomitant headache have similar outcomes after surgery. Our alternative hypothesis is that concomitant headache is a negative predictor for a favourable outcome of DCR surgery, i.e. an effect size less than the MCIC value for improvement.

Data source:

The project will use prospectively collected data from the Norwegian Registry for Spine Surgery (NORspine). The NORspine is a comprehensive national clinical registry, with a capture rate of patients operated for DCR of 75% from 2021 and a response rate at 12 months follow-up of 80% in 2022. The coverage rate at the institutional level is 95-100%.

Analyses and reporting will be conducted according to the methodology proposed by PROGRESS (prognosis research strategy) framework, and reported according to the STROBE (strengthening the reporting of observational studies in epidemiology) statement.

Data collection:

Demographic variables, smoking, educational level, duration of symptoms, status on sick leave, working and disability status are collected at admission (baseline). Comorbidity, diagnosis, treatment as well as perioperative complications are recorded by surgeons. Patient reported outcome measures (PROMs) are recorded at admission (baseline) and 3- and 12 months follow-up time) after surgery.

Statistical analyses:

The invastigators will select patients with both headache and neck pain assessed with the NRS to assess the frequency of DCR associated headache.

To determine the MCIC of DCR associated headache the invastigators will use the global perceived effect (GPE) scale as the external criterion (anchor). The invastigators will assess the mean NRS headache score at 12 months, change score between baseline and 12 months follow-up and the corresponding percentage change score. A cut-off value for the NRS headache MCIC will be obtained by assessing values of sensitivity and specificity receiver operating curve (ROC).

Univariable and multivariable analyses will be used to evaluate if NRS headache is a potential prognostic factor against the NDI (35% improvement (yes/no) using binary logistic regression, adjusted for a priori selection of confounding factors. A p-value of \<0.05 will be considered statistically significant.

Eligibility Criteria:
Inclusion criteria:

* Patients 16 years or above and operated for degenerative cervical radiculopathy (disc herniation or spondylosis)
* Single level or multiple (primary surgery)
* Anterior cervical discectomy and fusion with or without plate
* Artificial cervical disc replacement

Exclusion criteria:

* Degenerative cervical myelopathy, tumour, inflammation, infection and trauma
* Previous surgery in the cervical spine
* Corpectomy
* Posterior approach as laminectomi with or without fusion and foramenotomi