Queckenstedt's test repurposed for the quantitative assessment of the cerebrospinal fluid pulsatility curve

Abstract

Purpose: Before the era of spinal imaging, presence of a spinal canal block was tested through gross changes in cerebrospinal fluid pressure (CSFP) provoked by manual compression of the jugular veins (referred to as Queckenstedt's test; QT). Beyond these provoked gross changes, cardiac-driven CSFP peak-to-valley amplitudes (CSFPp) can be recorded during CSFP registration. This is the first study to assess whether the QT can be repurposed to derive descriptors of the CSF pulsatility curve, focusing on feasibility and repeatability.

Method: Lumbar puncture was performed in lateral recumbent position in fourteen elderly patients (59.7±9.3 years, 6F) (NCT02170155) without stenosis of the spinal canal. CSFP was recorded during resting state and QT. A surrogate for the relative pulse pressure coefficient was computed from repeated QTs (i.e., RPPC-Q).

Results: Resting state mean CSFP was 12.3 mmHg (IQR 3.2) and CSFPp was 1.0 mmHg (0.5). Mean CSFP rise during QT was 12.5 mmHg (7.3). CSFPp showed an average 3-fold increase at peak QT compared to the resting state. Median RPPC-Q was 0.18 (0.04). There was no systematic error in the computed metrics between the first and second QT.

Conclusion: This technical note describes a method to reliably derive, beyond gross CSFP increments, metrics related to cardiac-driven amplitudes during QT (i.e., RPPC-Q). A study comparing these metrics as obtained by established procedures (i.e., infusion testing) and by QT is warranted.

Keywords: Cerebrospinal fluid; Cerebrospinal fluid pressure; Queckenstedt’s test; Relative pulse pressure coefficient; Spinal cord compression.

Fig. 1

Basic concepts of the study. Flow diagram of cerebrospinal fluid pressure (CSFP) assessment during resting state (a), and Queckenstedt’s test (QT) (b), and the resulting pulsatility curve (c) in a representative patient (ID 059)

Fig. 2

(a) Schematic representation of the experimental setup (1–3) employed to test the frequency response of the pressure measurement system (4–8); 1: motor-driven piston pump, 2: bottle semi-filled with water, 3: first pressure transducer, 4: needle, 5: short connecting line, 6: three-way stopcock, 7: connecting tube, 8: second pressure transducer. (b) The ratio between the peak-to-valley amplitudes of the output and the input pressure signals, as measured by the second (8) and first pressure transducer (3), respectively, is reported for each investigated frequency

Fig. 3

Queckenstedt’s test (QT) derived cerebrospinal fluid pressure (CSFP) parameters. (a) Mean CSFP calculated using the time-reconstructed CSFP signal obtained with the frequency bins in the range 0–0.5 Hz. (b) Cardiac-driven CSFP peak-to-valley amplitude (CSFPp) followed from resting state and to QT, calculated using the time-reconstructed CSFP signal obtained with the frequency bins in the range 0.5–8 Hz. (c) CSFPp at resting state (blue dots) and during QT (black dots) is plotted against mean CSFP. The regression line (in black) is reported: the relative pulse pressure coefficient (RPPC-Q, 0.18) corresponds to the slope of such a line and P₀-Q (7.15) to the x-axis intercept. (d) Data from a single patient (ID 053) showing CSFPp at resting state (left of the vertical dashed line) and during QT (right of the vertical dashed line); during QT the positive correlation between mean CSFP and CSFPp is detected (P < 0.001, correlation coefficient = 0.66)

Fig. 4

Cerebrospinal fluid pressure (CSFP) rise plotted against mean CSFP at the resting state (no significant correlation, P = 0.867); each dot represents a patient (n = 14)

Fig. 5

Bland-Altman plots of Queckenstedt’s test (QT) derived metrics. Each dot represents single patient’s data, since two QTs were performed in each patient. (a) Cerebrospinal fluid pressure (CSFP) rise; bias: 0.8 mmHg (continuous blue line), 95% confidence interval of the bias: −1.9 – 3.6 mmHg (dashed blue lines), repeatability coefficient: −9.5 – 11.1 mmHg (dashed red lines). (b) Cardiac-driven CSFP peak-to-valley amplitude (CSFPp); bias: −0.5 mmHg (continuous blue line); 95% confidence interval of the bias: −1.0 – 0.1 mmHg (dashed blue lines); repeatability coefficient: −2.6 – 1.6 mmHg (dashed red lines). (c) Relative pulse pressure coefficient obtained through QT (RPPC-Q); bias: −0.04 (continuous blue line), 95% confidence interval of the bias: −0.10 – 0.02 (dashed blue lines), repeatability coefficient: −0.26 – 0.18 (dashed red lines). (d) Theoretical pressure at infinite compliance obtained through QT (P₀-Q); bias: −1.5 mmHg (continuous blue line), 95% confidence interval of the bias: −3.8 – 0.9 mmHg (dashed blue lines), repeatability coefficient: −10.3 – 7.4 mmHg (dashed red lines)