Cerebrospinal fluid flow dynamics study in Chiari I malformation: implications for syrinx formation

Abstract

<jats:p>Cerebrospinal fluid (CSF) flow abnormalities are known to be present in Chiari I malformation and to underlie the origin and progression of associated syringomyelia. The incidence of syrinx formation, however, is variable for unknown reasons. The aim of this study was to investigate whether differences in CSF flow dynamics in patients with Chiari I malformation may account for the different clinical and radiological presentation.</jats:p> <jats:p>Presurgical and postsurgical phase-contrast magnetic resonance imaging investigations were prospectively conducted in 47 adult patients with symptomatic Chiari I malformation. Patients were divided into two groups according to the presence (32 cases) or absence (15 cases) of syrinx. Cerebrospinal fluid flow patterns were evaluated at four regions of interest: prebulbar cistern, foramen magnum, and the ventral and dorsal spinal subarachnoid spaces at the C-5 level. A temporal analysis of CSF flow waveforms was performed with measurement of cranial- and caudal-directed flow durations. All patients underwent a craniocervical decompressive procedure. Preoperatively, a prolonged caudal-directed (systolic) flow pattern was observed in patients with syringomyelia, as compared with normal control values obtained in 15 healthy volunteers. Conversely, a decreased systolic duration was observed in Chiari I patients who had malformation without syrinx. These trends were not statistically significant because of the considerable degree of overlap with the control values recorded in both groups. Additional comparison of the observed preoperative values obtained in patients with and those without syringomyelia indicated that the difference in systolic flow duration was significant at the ventral spinal subarachnoid space level (p = 0.003) and remarkable at the other levels, although not reaching statistical significance. Cerebrospinal fluid flow was minimal or absent at the foramen magnum (dorsal aspect) due to tonsillar herniation, precluding reliable quantitative measurement at this level. There was no evidence of communication between the fourth ventricle and syrinx in any case. Postoperatively, unobstructed CSF flow was recorded across the enlarged foramen magnum and into the artificial cisterna magna in all patients. A gradual restoration of near-normal flow patterns was observed in both groups. Inside the syrinx, fluid motion gradually tapered, no longer being detectable in 12 patients (37.5%) 1 year postsurgery.</jats:p> <jats:p>In patients with Chiari I malformation and associated syringomyelia different CSF flow patterns were demonstrated as compared with patients in whom syrinx was absent. Analysis of this study's findings supports the hypothesis that in Chiari I malformation an elongated systolic flow may prolong the condition of increased spinal subarachnoid pressure caused by the junctional obstruction, thus favoring CSF penetration into the spinal cord. It may be also proposed that a shortened systolic flow may be insufficient to maintain a hypertensive condition for enough time to induce syrinx formation.</jats:p>

Pediatric and adult Chiari malformation Type I surgical series 1965–2013: a review of demographics, operative treatment, and outcomes

“…[1][2][3][4][5][6][7][8][9][11][12][13][14][15][16][17][18][19][65][66][67]70,71,100,[102][103][104][105][106][107][108][109][110][111][113][114][115][116][117][118][119][120][121][122][123][124][125][126][127][128][129][130][132]…”

“…4,8,13,14,[16][17][18][19]21,22,29,36,45,48,49,57,62,71,79,82,84,85,95,105,113,[118][119][120][122][123][124][125]127,128,137,149,151 In the pediatric series that reported an association of syringomyelia, of a total of 1678 patients, 673 (40%) harbored a syrinx. [1][2][3]15,24,28,[30][31][32][33]35,41,42,50,51,…”

The post–syrinx syndrome: stable central myelopathy and collapsed or absent syrinx

“…The persistence of dysesthetic pain (especially in group B) was characteristic for patients with collapse of their syrinxes [35]. Patients of both groups had similar bony and CSF space abnormalities at the CVJ and PF (Table) [16,43,45]. Syrinxes in some patients of group B were very narrow (Fig.…”

“…Several pathophysiological factors are proposed to promote syringomyelia development: 1) reduction of subarachnoid compliance and accentuated pulse pressure in the cervical portion of the spinal subarachnoid space [16,43], 2) increased intrasyrinx pressure [36], 3) pressure gradients within the intramedullary extracellular fluid [23], 4) intrasyrinx fluid pulsation [9], 5) pulsation of the intramedullary arteries [51], and 6) patency of the central canal of the spinal cord [33]. However, because communication between the syrinx and fourth ventricle is usually not found in radiographic or post-mortem studies, it cannot play a role in pathogenesis of most cases of syringomyelia [34,43,45].…”

“…Although the pathogenesis of CM1-associated syringomyelia is not completely understood, abnormal CSF flow at the foramen magnum (FM) and upper cervical spinal canal appears to influence the creation and progression of syrinxes [9,16,20,43,45]. Several pathophysiological factors are proposed to promote syringomyelia development: 1) reduction of subarachnoid compliance and accentuated pulse pressure in the cervical portion of the spinal subarachnoid space [16,43], 2) increased intrasyrinx pressure [36], 3) pressure gradients within the intramedullary extracellular fluid [23], 4) intrasyrinx fluid pulsation [9], 5) pulsation of the intramedullary arteries [51], and 6) patency of the central canal of the spinal cord [33].…”