Study protocol for an observational study of cerebrospinal fluid pressure in patients with degenerative cervical myelopathy undergoing surgical deCOMPression of the spinal CORD: the COMP-CORD study

Abstract

Introduction: Degenerative cervical myelopathy (DCM) is a disabling spinal disorder characterised by sensorimotor deficits of upper and lower limbs, neurogenic bladder dysfunction and neuropathic pain. When suspected, cervical MRI helps to reveal spinal cord compression and rules out alternative diagnoses. However, the correlation between radiological findings and symptoms is weak. Cerebrospinal fluid pressure (CSFP) analysis may complement the appreciation of cord compression and be used for intraoperative and postoperative monitorings in patients undergoing surgical decompression.

Methods and analysis: Twenty patients diagnosed with DCM undergoing surgical decompression will receive standardised lumbar CSFP monitoring immediately before, during and 24 hours after operation. Rest (ie, opening pressure, CSF pulsation) and stimulated (ie, Valsalva, Queckenstedt's) CSFP-findings in DCM will be compared with 20 controls and results from CSFP monitoring will be related to clinical and neurophysiological findings. Arterial blood pressure will be recorded perioperatively and postoperatively to calculate spinal cord perfusion pressure and spinal vascular reactivity index. Furthermore, measures of CSFP will be compared with markers of spinal cord compression by means of MR imaging.

Ethics and dissemination: The study protocol conformed to the latest revision of the Declaration of Helsinki and was approved by the local Ethics Committee of the University Hospital of Zurich (KEK-ZH number PB-2016-00623). The main publications from this study will cover the CSFP fluid dynamics and pressure analysis preoperative, perioperative and postoperative correlated with imaging, clinical scores and neurophysiology. Other publications will deal with preoperative and postoperative spinal perfusion. Furthermore, we will disseminate an analysis on waveform morphology and the correlation with blood pressure and ECG. Parts of the data will be used for computational modelling of cervical stenosis.

Trial registration number: ClinicalTrials.gov Registry (NCT02170155).

Keywords: adult neurology; neurophysiology; neurosurgery; spine.

Figure 1

Cervical sagittal and axial T2w MRI sequences in a representative patient with degenerative cervical myelopathy showing narrowed spinal canal, hyperintense T2w lesions, effacement of the cerebrospinal fluid signal, impression of the spinal cord, and reduced diameter (91.55 mm²) at the level of maximum stenosis C4/C5 (orange lines).

Figure 2

Bedside CSFP recordings (60 s, x-axes) of CSFP in mm Hg (y-axes) in a patient without (HC; left) and with cervical stenosis (DCM; right). Blue arrows mark the onset of provocation manoeuvres with jugular vein compression (Queckenstedt’s test; upper rows) and Valsalva manoeuvre (lower rows), respectively, represented by the pictograms. Upper rows: without stenosis, CSFP was pulsatile (corresponding heart rate around 80 pulses/minute) and rapidly increased from baseline pressure of 12 mm Hg to 27 mm Hg during Queckenstedt’s test. In the presence of stenosis, cardiac pulsations were absent, but the signal was still modulated with respiration (corresponding respiratory rate about 18–20/min). Queckenstedt's test was not responsive, that is, CSFP did not react to jugular vein pressure, indicating spinal block. Lower rows: during Valsalva maneuver CSFP increased in both participants to values well above 50 mm Hg. This indicates that different physiological mechanisms are responsible for pressure increase in Queckenstedt’s test and Valsalva manoeuvre. Due to more pressure increase with Valsalva test stenosis can be overcome and therefore response is positive in the patient with DCM as well. CSFP, cerebrospinal fluid pressure; DCM, degenerative cervical myelopathy; HC, healthy control.