CSF Flow Different In Patients With Cough Headaches

March 31st, 2011 -- While a cough triggered headache in the back of the head is often considered to be the signature symptom of Chiari, some Chiari patients get different kinds of headaches, and some don't get headaches at all. In a recent on-line publication in the journal, AJNR, a group of Boston researchers (Bhadelia) showed that the CSF flow of Chiari patients who get cough associated headaches (CAH) were significantly different than Chiari patients who do not get those types of headaches as measured by MRI.

The natural flow of CSF between the brain and spinal areas is driven by the cardiac cycle. During the systole phase of the cardiac cycle, the heart muscles contract and push blood out through the arteries. When this blood flows in the brain, because it is essentially a fixed space, CSF is forced out from the brain and down into the spinal area. During the second phase of the cardiac cycle. diastole, this process is reversed and CSF flows from the spine back into the brain.

Based on theories that Chiari cough headaches are due to CSF pressure differences in the brain and spine, the Boston research team decided to use cine PC MRI to study the CSF flow in Chiari patients both with and without cough headaches. Specifically, they retrospectively looked at 30 Chiari patients, ranging in age from 5 - 64 years, who had been scanned on a single MRI machine. Patients with prior Chiari surgery or who moved too much during the scan were excluded. Patients were considered to suffer from CAH if they made specific note of it during their clinical visit, which 9 of the 30 did.

Based on the PC MRI scans, the researchers measure the CSF velocity throughout the cardiac cycle at two different locations: just below the foramen magnum and between the second and third cervical vertebrae. Figure 1 below shows what a CSF velocity plot might look like:

Figure 1: Representation of CSF Velocity Plot

CSF%20Fl1.gif

When the velocity has a positive value, CSF is flowing from the brain to the spine, and when it has a negative value, it is flowing from the spine to the brain. In this fashion, the authors defined CSF systole and diastole graphically as a fraction of one cardiac cycle.

When the scientists looked at the CSF plots of the CAH patients versus the no CAH patients, they did not find much difference in the actual velocities of the CSF, but they did find a significant difference in the relative time of CSF diastole (Table 1). Specifically, the average CSF diastole - where the CSF is flowing from the spine to the head - took up much more of the cardiac cycle as a fraction in the CAH patients as opposed to the non-CAH patients (78% vs 59%). This is shown graphically in Figure 2 below:

Figure 2: CSF Waveform CAH vs No CAH

CSF%20Fl2.gif

It should be noted that this difference was only found with the measurements just below the foramen magnum, and that the measurements taken further down the spine in the cervical region showed no significant differences between the groups. It is also interesting to note that the systole/diastole composition of the cardiac cycle was not related at all to whether patients had a syrinx.

While the true clinical implications of this study are not clear, it does provide strong evidence of a physiological difference between Chiari patients with cough headaches and those without. The researchers disclose that a drawback of this work is that the acquisition time to get these types of MRI measurements is quite long which makes it difficult from a practical point of view.

However, Conquer Chiari is funding a pilot study designed by Dr. Bhadelia to use a new type of MRI technique to perform a similar study in Chiari patients during Valsalva.


Table 1: CSF Flow Differences in Patients with CAH (9) vs No CAH (21),
Measured Just Below Foramen Magnum

No CAH CAH Sig
Max Systolic CSF Velocity (mm/s) 22.8 23.6 No
Mas Diastolic CSF Velocity (mm/s) 16.4 20.5 No
CSF Systole Fraction of Cardiac Cycle 41% 28% Yes
CSF Diastole Fraction of Cardiac Cycle 59% 72% Yes

Note: Sig refers to whether the difference between groups is statistically significant and not likely due to chance


Related C&S News Articles:

Chiari Accounts For Half Of All Cough Headaches

Study Explores The Chiari-Migraine Connection

What causes the dreaded Chiari cough headache?