A Simple Way to Localize Spinal Lesions

This study of 41 dogs with thoracolumbar spinal cord injuries evaluated the accuracy of the cutaneous trunci reflex to localize lesions and assess the correlation between focal loss of the reflex and injury severity. Thoracolumbar spinal injuries are commonly assessed on a scale of 0–5, but this scale does not allow for gradations within dogs with ambulatory paraparesis. A 14-point grading scale provides more detailed prognostic information, but necessary video gait analysis limits its utility.

In this study, cutaneous trunci reflex cut-off was seen in 33 (80%) dogs at 0­­–4 vertebrae caudal to the maximal spinal lesion. Lesions were identified on MRI; in 16 (48.5%) dogs, the lesion was either 2 or 3 vertebrae caudal to the lesion. Reflex cutoff occurred at less severe grades than did ambulatory paresis. In addition, in dogs with ambulation loss, there was a significant positive correlation between loss of the cutaneous trunci reflex and more severe clinical grades. Loss of cutaneous trunci reflex may classify dogs with ambulatory paresis into more or less severely affected groups, allowing for more ability to localize lesions and further prognostic information.

CommentaryThis study demonstrated that the cutaneous trunci reflex is relatively accurate and can help localize the lesion in the T3–L3 region of the spinal cord. If the cutaneous trunci reflex is present at L6, there is no need to proceed cranially because the entire pathway is intact. Although this study showed that the cutaneous reflex was elicited in all patients tested, lack of cutaneous trunci reflex can be observed in normal patients. Although there was a fairly wide range of cutoff locations compared with maximal lesion location, other examination findings (eg, presence of spinal pain) can be used to further localize the lesion. Unilateral cutaneous trunci reflex cutoff can also help localize the side of the lesion, which can be useful in deciding where to perform surgery.—Mark Troxel, DVM, DACVIM (Neurology)

SourceThe cutaneous trunci reflex for localising and grading thoracolumbar spinal cord injuries in dogs. Gutierrez-Quintana R, Edgar J, Wessman A, Cherubini GB, Penderis J. J SMALL ANIM PRACT 53:470-475, 2012.