Purpose:
Patients with craniocervical trauma (whiplash or mild traumatic brain injury) and craniocervical instability due to other reasons (ex: Ehlers Danlos Syndrome, EDS) often complain of a characteristic headache that originates in the occipital region (1,2). These patients also present with a constellation of other neurologic symptoms including tinnitus, visual disturbances, gait difficulty, and syncopal episodes. This group of non-focal neurologic symptoms has been described as the craniocervical syndrome (CCS), but the physiologic basis is not fully understood (3). It has been reported that alterations in CSF flow are associated with occipital headache in patients with Chiari I malformation regardless of the degree of tonsillar ectopia, suggesting that decreased CSF flow may be responsible for the symptoms (4). Due to the similar symptoms in Chiari and CCS, we hypothesize that the etiology of CCS is related to CSF dynamics. This retrospective study aims to identify the relationship between chronic occipital headache and CSF flow in patients with suspected CCS. 

Materials and Methods:
16 patients (6 male, mean age =48.4) with the primary complaint of occipital headache were chosen from the adult patient population referred to our MRI center for clinically suspected CCS. 11 patients had prior head/neck trauma, 2 patients had EDS, and 3 patients had no discernible history of trauma or connective tissue disorder. Patients with any major neurological disorder or spinal surgery were excluded. 18 asymptomatic volunteers (8 male, mean age= 48.4) were used as controls. All subjects underwent MRI in a sitting position on a 0.6T positional MRI. A phase encoded sequence was applied with peripheral gating to image and quantify CSF flow. CSF flow data was obtained at the midC2 level. Unpaired t-test was used to compare the CSF parameters between the two groups. One of two radiologists reviewed each brain MRI to assess the position of the cerebellar tonsils. 
Results:
A significant decrease in CSF stroke volume per cardiac cycle (p=0.029) and total systolic CSF flow (p=0.044) was seen in CCS patients (Fig. 1). No CCS patients exhibited cerebellar tonsillar ectopia (CTE) >5mm: 5 patients had CTE 1-4mm, and 11 patients had no CTE. 
Conclusions:
Our results suggest that occipital headache is related to decreased CSF flow even in the absence of Chiari I malformation and that alterations in CSF dynamics may be responsible for CCS. Further study is warranted into the e!ect of head and neck trauma on CSF hydrodynamics.

Cerebrospinal Fluid Flow Alterations in Craniocervical Syndrome: A Phase-Contrast MRI Study

[Virtual Conference Page](https://event.vconferenceonline.com/microsite/html/login.aspx?id=1551&rlp=1)

[ASNR Website] (https://www.asnr.org//annualmeeting)

[Educational Exhibits](https://www.morressier.com/event/asnr2020exhibit/5e5d0be000701ceba4a26941)