Tag: myelography

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Origin of Syrinx Fluid in Syringomyelia: A Physiological Study

Neurosurgery 84:457–468, 2019

The origin of syrinx fluid is controversial.

OBJECTIVE: To elucidate themechanisms of syringomyelia associated with cerebrospinal fluid pathway obstruction and with intramedullary tumors, contrast transport from the spinal subarachnoid space (SAS) to syrinx was evaluated in syringomyelia patients.

METHODS: We prospectively studied patients with syringomyelia: 22 with Chiari I malformation and 16 with SAS obstruction-related syringomyelia before and 1 wk after surgery, and 9 with tumor-related syringomyelia before surgery only. Computed tomographymyelography quantified dye transport into the syrinx before and 0.5, 2, 4, 6, 8, 10, and 22 h after contrast injection by measuring contrast density in Hounsfield units (HU).

RESULTS: Before surgery, more contrast passed into the syrinx in Chiari I malformation related syringomyelia and spinal obstruction-related syringomyelia than in tumor-related syringomyelia, as measured by (1) maximum syrinx HU, (2) area under the syrinx concentration-time curve (HU AUC), (3) ratio of syrinx HU to subarachnoid cerebrospinal fluid (CSF; SAS) HU, and (4) AUC syrinx/AUC SAS. More contrast (AUC) accumulated in the syrinx and subarachnoid space before than after surgery.

CONCLUSION: Transparenchymal bulk flow of CSF from the subarachnoid space to syrinx occurs in Chiari I malformation-related syringomyelia and spinal obstruction-related syringomyelia. Before surgery, more subarachnoid contrast entered syringes associated with CSF pathway obstruction than with tumor, consistent with syrinx fluid originating from the subarachnoid space in Chiari I malformation and spinal obstruction-related syringomyelia and not from the subarachnoid space in tumor-related syringomyelia. Decompressive surgery opened subarachnoid CSF pathways and reduced contrast entry into syringes associated with CSF pathway obstruction.

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Axial Loading During Magnetic Resonance Imaging in Patients With Lumbar Spinal Canal Stenosis

SPINE Volume 37, Number 16, pp E-985–E992

We compared the sizes of the dural sac among conventional magnetic resonance imaging (MRI), axial loaded MRI, and upright myelography in patients with lumbar spinal canal stenosis (LSCS).

Objective. To determine whether axial loaded MRI can demonstrate similar positional changes of the dural sac size as were detected by upright myelography in LSCS.

Summary of Background Data. In patients with LSCS, constriction of the dural sac is worsened and symptoms are aggravated during standing or walking. To disclose such positional changes, upright myelography has been widely used. Recently, axial loaded MRI, which can simulate a standing position, has been developed. However, there has been no study to compare the dural sac size between axial loaded MRI and upright myelography.

Methods. Forty-four patients underwent conventional MRI, axial loaded MRI, and myelography. Transverse and anteroposterior diameters and the cross-sectional areas of the dural sac from L2– L3 to L5–S1 were compared. Pearson correlations of the diameters between the MRIs and the myelograms were analyzed. On the basis of the myelograms, all disc levels were divided into severe and nonsevere constriction groups. In each group, the diameters and the cross-sectional areas were compared. Sensitivity and specifi city to detect severe constriction were calculated for the conventional and axial loaded MRI.

Results. Transverse and anteroposterior diameters at L4–L5 in the axial loaded MRI and myelogram were signifi cantle smaller than those observed in the conventional MRI ( P < 0.001). Crosssectional areas in the axial loaded MRI were signifi cantly smaller than those in the conventional MRI at L2–L3, L3–L4, and L4–L5 ( P < 0.001). Between the axial loaded MRI and the myelography, Pearson correlation coeffi cients of the transverse and anteroposterior diameters were 0.85 and 0.87, respectively ( P < 0.001), which were higher than those for conventional MRI. Reductions of the dural sac sizes in the axial loaded MRI were more evident in the severe constriction group. The axial loaded MRI detected severe constriction with a higher sensitivity (96.4%) and specifi city (98.2%) than the conventional MRI.

Conclusion. The axial loaded MRI demonstrated a significant reduction in the dural sac size and signifi cant correlations of the dural sac diameters with the upright myelogram. Furthermore, the axial loaded MRI had higher sensitivity and specifi city than the conventional MRI for detecting the severe constriction observed in the myelogram. Therefore, the axial loaded MRI can be used to represent positional changes of the dural sac size detected by the upright myelography in patients with LSCS.

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