Measurement and characterization of cough induced subarachnoid space pressure wave reverberations during lumbar puncture
If you would like to help with this study as a master's or bachelor's thesis project, please send Bryn Martin an email with your resume and research interests.
- Bryn Martin
- Currently seeking a neurologist or neurosurgeon interested in this project. Please contact Bryn Martin if you are interested.
Craniospinal compliance (CC) has been hypothesized to be an important indicator of craniospinal health as it is related to intracranial pressure (ICP). However, mean ICP does not provide information about CC. For example, in some people ICP could be normal, but CC could be low. Recent research has supported that healthy CC is needed to properly dampen the cerebral blood flow (CBF) pulsations (Madsen, Egnor et al. 2006; Luciano and Dombrowski 2007). If CC is insufficient, ICP fluctuations would be altered and these alterations could have an impact on transport, production, or absorption of cerebrospinal fluid (CSF).
CC assessment could be an important tool to help diagnose craniospinal disorders such as normal pressure hydrocephalus. It has been hypothesized that elevated CSF pulse pressure amplitude, as a result of insufficient CC, may be an underlying cause for normal pressure hydrocephalus (Eide and Brean 2006; Czosnyka, Keong et al. 2008; Eide and Sorteberg 2008) and related craniospinal disorders. However, healthy and abnormal CC levels have not yet been established. At present, CC is difficult to assess since the subarachnoid space is enclosed within bone and meninges of the nervous system and the currently used techniques for CC assessment require sophisticated CSF infusion tests. Thus, a simple technique for CC measurement could be helpful for diagnosis and post-surgical assessment.
CC can be obtained by recording CSF pressure wave reverberations in the SSS due to a cough input during lumbar puncture. Williams (Williams 1976) recorded CSF pressure reverberations of ~ 3.5 Hz following a cough (Figure 1). If a total length of the SSS is assumed to be 0.5 m, the wave would travel ~ 1 m for a round trip and thus would imply a SSS PWV of 3.5 m/s. This PWV is near the SSS velocity propagation velocity calculated by Kalata et al. in the cervical SSS (4.6 m/s) using a high-temporal resolution phase encoded MRI velocity technique (Kalata, Martin et al. 2009).
The pressure reverberations in the SSS are a result of the CSF pressure wave reflecting back and forth along the spine and can be used to determine the SSS pressure wave velocity (PWV), an indicator of CC. In analogy, the arterial PWV has been shown to be an important diagnostic tool in cardiovascular disease (Asmar, Benetos et al. 1995) and could have a similar impact for the CSF system. Thus, Measurement of the CSF pressure propagation wave velocity (PWV) in the spinal subarachnoid space (SSS) could give information about CC and be a tool to help diagnose and assess craniospinal disorders such as hydrocephalus.
Hypothesis and research objectives
We hypothesize that the SSS PWV can be measured in patients undergoing lumbar puncture by observing the pressure reverberations produced by coughing and that the pressure reverberation frequency will be impacted by the drainage of CSF.
Methods and study outline
We propose to conduct CSF pressure measurements during a lumbar puncture procedure in 30 subjects using the following protocol. The duration of the entire project is estimated to be 1 year.
- Measurement protocol. The subject’s spine length will be measured from the foramen magnum to the coccyx along with subject age, sex, weight, and height. The subject will be asked to lie in the dorsolateral position at 0 degrees tilt and a 25 gauge needle will be inserted at the lumbar spine until CSF outflow is observed. Needle location will be recorded. A two way valve will be connected to the needle with one end leading to the normal lumbar opening pressure tube and the other directly connected to a pressure recording device. The subject will be asked to cough three times while the lumbar pressure is recorded. The opening pressure will then be recorded and 30-50 ml of CSF will be removed for biological testing and recorded. The subject will then be asked to cough three more times while the pressure is recorded. See Figure 2 for lumbar pressure measurement apparatus schematic.
- Data analysis. The pressure recordings will be analyzed to determine the damped natural frequency and damping ratio by spectral analysis. As a first estimate, the SSS will be assumed to act as a flexible tube with uniform cross-sectional area and homogenous properties. The natural frequency along with the subject spine length will be used to determine the SSS PWV. PWV measurements will be examined before and after the removal of CSF and to determine the possibility of age, sex, height, and weight relationships.
Expected results and potential impact
This project will quantify the SSS CSF PWV in healthy subjects before and after CSF drainage. If shown effective, the technique could be used to determine if SSS PWV is an indicator of various craniospinal disorders such as normal pressure hydrocephalus.
To be posted.
Asmar, R., A. Benetos, et al. (1995). "Assessment of arterial distensibility by automatic pulse wave velocity measurement. Validation and clinical application studies." Hypertension 26(3): 485-490.
Czosnyka, Z., N. Keong, et al. (2008). "Pulse amplitude of intracranial pressure waveform in hydrocephalus." Acta Neurochir Suppl 102: 137-140.
Eide, P. K. and A. Brean (2006). "Intracranial pulse pressure amplitude levels determined during preoperative assessment of subjects with possible idiopathic normal pressure hydrocephalus." Acta Neurochir (Wien) 148(11): 1151-1156; discussion 1156.
Eide, P. K. and W. Sorteberg (2008). "Changes in intracranial pulse pressure amplitudes after shunt implantation and adjustment of shunt valve opening pressure in normal pressure hydrocephalus." Acta Neurochir (Wien) 150(11): 1141-1147; discussion 1147.
Kalata, W., B. A. Martin, et al. (2009). "MR measurement of cerebrospinal fluid velocity wave speed in the spinal canal." IEEE Trans Biomed Eng 56(6): 1765-1768.
Luciano, M. and S. Dombrowski (2007). "Hydrocephalus and the heart: interactions of the first and third circulations." Cleve Clin J Med 74 Suppl 1: S128-131.
Madsen, J. R., M. Egnor, et al. (2006). "Cerebrospinal fluid pulsatility and hydrocephalus: the fourth circulation." Clin Neurosurg 53: 48-52.
Williams, B. (1976). "Cerebrospinal fluid pressure changes in response to coughing." Brain 99(2): 331-346.