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. 2021 Jan;35(1):363-371.
doi: 10.1111/jvim.16023. Epub 2021 Jan 11.

Association between filum terminale internum length and pain in Cavalier King Charles spaniels with and without syringomyelia

Courtney R Sparks  1 , Christian Woelfel  1 , Ian Robertson  2 , Natasha J Olby  1   3
Affiliations

Association between filum terminale internum length and pain in Cavalier King Charles spaniels with and without syringomyelia

Courtney R Sparks et al. J Vet Intern Med. 2021 Jan.

Abstract

Background: Lumbar syringomyelia (SM), lumbosacral pain, and more caudal spinal cord termination are reported in Cavalier King Charles spaniels (CKCS). Data are lacking on the clinical relevance of alterations in their spinal cord terminal structures.

Objectives: To compare spinal cord termination level and filum terminale internum length (FTIL) with presence of lumbar SM and clinical signs in CKCS.

Animals: Forty-eight CKCS.

Methods: In this prospective study, pain was quantified using owner and clinician assessments. Vertebral level of spinal cord and dural sac termination, presence of SM, and FTIL were determined from sagittal magnetic resonance imaging (MRI) sequences. Kappa and intraclass correlation (ICC) analyses determined interobserver reliability. The MRI findings were compared to owner and clinician-reported pain quantification.

Results: Interobserver reliability was good for spinal cord and dural sac termination (kappa = 0.61 and 0.64, respectively) and excellent for FTIL (ICC: 92% agreement). The spinal cord terminated at 6th lumbar vertebra in 1, 7th lumbar vertebra in 31, and the sacrum in 15 dogs, and termination level was associated with lumbar SM (P = .002) but not clinical signs. Mean FTIL was 2.9 ± 1.08 mm; it was associated with owner-reported pain (P = .033) and spinal palpation scores (P = .023). Painful CKCS without SM had shorter FTIL compared to normal CKCS and painful CKCS with SM (P = .02).

Conclusions: Painful CKCS without SM have decreased distance between the termination of the spinal cord and dural sac, suggesting a shorter FTIL. More caudal spinal cord termination is associated with development of lumbar SM.

Keywords: Chiari-like malformation; conus medullaris; dural sac; morphometry; tethered cord.

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Conflict of interest statement

Authors declare no conflict of interest.

Figures

FIGURE 1
FIGURE 1
Determination of filum terminale internum length (FTIL) using half‐Fourier acquisition single‐shot turbo spin echo (HASTE) sequences. Panel A demonstrates a straight‐line measurement from the end of the conus (hypointense signal) to the end of the dural sac (bright hyperintense signal). Panel B demonstrates the length measurements using multiple straight‐line measurements due to the angle of the lumbosacral junction
FIGURE 2
FIGURE 2
Scatterplots of the correlation among filum terminale internum length (FTIL) and, A, total scratch score (TSS) (P = .79), B, total pain score (TPS) (P adj = .034), and, C, combined palpation score (P adj = .015). The blue line reflects the linear fit of the data and the light blue shaded region is the 95% confidence region for the fitted line
FIGURE 3
FIGURE 3
A, Spinal cord and, B, dural sac termination in Cavalier King Charles spaniels (CKCS) with and without lumbar syringomyelia (SM). Each stacked bar shows the relative count for each group terminating at every vertebral level. L6, lumbar vertebrae 6; L7, lumbar vertebrae 7; Sa, sacrum; Cd, caudal vertebrae
FIGURE 4
FIGURE 4
‐ Box plots showing filum terminale internum length (FTIL) measurements for normal Cavalier King Charles spaniels (CKCS), asymptomatic dogs with syringomyelia (SM), painful dogs without SM (Chiari‐like malformation [CM] pain), and painful dogs with SM. The horizontal line within the boxplot represents the median, the ends of the box represent the interquartile range, the upper and lower whisker extend 1.5 × interquartile range from the top and bottom of the box.*P = .02
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