Variation in the position of the conus medullaris and dural sac in adult dogs

Khan, Zohra; Munro, Elizabeth; Shaw, Darren; Faller, Kiterie M E

doi:10.1136/vr.105279

Cited by 10 publications

(16 citation statements)

References 20 publications

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“…Recently, it has been described with the use of magnetic resonance imaging (MRI) that the DS remained in a constant position regardless of the size of the dog. It was observed that in most of the patients, the DS extended to the LS space or caudal to it (Khan et al, 2019). In contrast, another study where MRI was used to compare Cavalier King Charles Spaniels (CKCS) with other small breed dogs up to 14 kg of body weight, showed that only in 66% of CKCS the DS reached the LS space, data more similar to our study (Sparks et al, 2019).…”

Section: Discussionsupporting

confidence: 87%

“…Although there are several publications regarding complications associated with epidural injection in dogs (Jones, 2001;Martorell and Cilli, 2020), none described spinal cord damage during the performance of an epidural technique. In contrast, a microscopic examination of the spinal cord after myelography performed at L5-L6 intervertebral space, revealed haemorrhage, axonal degeneration, and gliosis in five dogs, showing the direct trauma after spinal cord puncture (Kishimoto et al, 2004). After these findings, some authors have recommended the LS space as an alternative to the conventional lumbar myelography puncture site (L5-L6) in dogs, since it often allows a subarachnoid puncture for the injection of contrast medium avoiding damage to the spinal cord (Iseri et al, 2004).…”

Section: Discussionmentioning

confidence: 76%

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Dural sac localization using myelography and its application to the lumbosacral epidural in dogs

Zapata¹,

Ros²,

Álvarez³

et al. 2021

Open Vet J.

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Background: The techniques described for the identification of the lumbosacral (LS) epidural space in dogs do not guarantee the needle position or an accidental subarachnoid puncture, especially in small size dogs.Aim: To determine the relationship between body weight and the location of the dural sac (DS) using myelography in dogs, and to determine the possibility of subarachnoid puncture during LS epidural based on the position of the DS.Methods: Four masked observers evaluated 70 myelographic studies of dogs, annotating the vertebrae where the DS ended, if it was localized before or after the LS space, and if accidental subarachnoid puncture during LS epidural injection was possible (yes/no). Body weight (kg) was categorized into: less than 10 kg, between 10 and 20 kg, and more than 20 kg and was also converted to body surface area (BSA) as a continuous variable.Results: The DS ended at the LS space or caudally in 50% of dogs. There was a statistically significant difference between the position of the DS and the dog’s BSA (p = 0.001). The DS ended caudal to the LS space in 72.7% of dogs weighing <10 kg, in 25% of dogs between 10 and 20 kg and in 15% of dogs in the >20 kg category. The observers considered a possible subarachnoid puncture during LS epidural in 69.7% of patients <10 kg, 16.6% on those between 10 and 20 kg, and in 11.7% of the dogs >20 kg.Conclusion: The DS ended caudal to the LS space in almost 3/4 dogs in the <10 kg category, so accidental subarachnoid puncture during LS epidural is highly possible in this weight range.

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Section: Discussionsupporting

confidence: 87%

Section: Discussionmentioning

confidence: 76%

Dural sac localization using myelography and its application to the lumbosacral epidural in dogs

Zapata¹,

Ros²,

Álvarez³

et al. 2021

Open Vet J.

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“…Furthermore, a recent study demonstrated that conus medullaris position, not dural sac position, is dependent on size in dogs. 45 The study reported that the most com- nale internum is markedly elastic and has greater capacity to withstand strain than do the conus medullaris and filum terminal externum. 47 A thickened filum terminale has been extensively described as a cause of TCS in people.…”

Section: Discussionmentioning

confidence: 99%

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

Sparks

Woelfel

Robertson

et al. 2021

Veterinary Internal Medicne

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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.

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“…A previous study 8 shows that the position of the CM in dogs positioned with their pelvic limbs in a neutral posture was more cranial in heavier dogs. In that study, for dogs that weighed between 10 and 15 kg, similar to the body weight of dogs in our study, the CM was located at a level that was in the cranial to the middle area of L7 when imaged in the neutral position, consistent with findings for the dogs of the present study.…”

Section: Discussionmentioning

confidence: 84%

“…1,[3][4][5] In people, the CM has a relatively consistent location, size, and shape 6 ; however, in dogs, the size of the dog and vertebral column influence the locations of the CM and cauda equina. 7,8 This variation in dogs further contributes to difficulties in diagnosing underlying conditions, such as tethered cord syndrome and congenital malformation of the filum terminale. [9][10][11] Although tethered cord syndrome can be diagnosed in people on the basis of the CM terminating distal to L2 (versus at the level of L1 for unaffected individuals), 10,12 diagnosing tethered cord syndrome in dogs is challenging because the location of the CM varies in dogs and because of limitations with conventional static MRI.…”

mentioning

confidence: 99%

Translocation of the conus medullaris during dynamic lumbosacral magnetic resonance imaging in dogs

Nam

Kang

Kim

et al. 2021

ajvr

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OBJECTIVETo investigate the change in the lumbosacral angle (∆LSA) and conus medullaris (CM) displacement in healthy dogs undergoing dynamic MRI with changes in the posture of their pelvic limbs from neutral posture to flexion or extension posture and to evaluate for potential correlation between ∆LSA and CM displacement. ANIMALS 9 healthy adult Beagles. PROCEDURESDogs underwent dynamic MRI with their pelvic limbs positioned in neutral, flexion, and extension postures. From T2-weighted sagittal midline plane MRI images, 2 observers measured the lumbosacral angle and CM location in duplicate for each posture for each dog. Intra-and interobserver agreement was assessed, and the Spearman rank correlation coefficient (ρ) was used to assess for potential correlation between ∆LSA and CM displacement for changes in pelvic limb posture from neutral to flexion or extension. RESULTSOverall, the mean ∆LSA and CM displacement for changes in posture were 23° and 9.09 mm (caudal displacement) for the change from neutral to flexion posture, 8.4° and −2.5 mm (cranial displacement) for the change from neutral to extension posture, and 32.2° and 11.64 mm (caudal displacement) for the change from extension to flexion posture. The ∆LSA strongly correlated (ρ = 0.705; 95% CI, 0.434 to 0.859) with displacement of the CM. CONCLUSIONS AND CLINICAL RELEVANCEThe use of dynamic MRI, compared with conventional MRI, will better help to characterize clinically normal and abnormal features of the lumbosacral region of the vertebral column and associated spinal cord during postural changes. Further, when limited translocation of the CM is evident on dynamic MRI, veterinarians should suspect underlying lumbosacral pathophysiologic processes or anatomic abnormalities.

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Variation in the position of the conus medullaris and dural sac in adult dogs

Cited by 10 publications

References 20 publications

Dural sac localization using myelography and its application to the lumbosacral epidural in dogs

Dural sac localization using myelography and its application to the lumbosacral epidural in dogs

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

Translocation of the conus medullaris during dynamic lumbosacral magnetic resonance imaging in dogs

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