Comparative clinical and morphometric investigations of cervical stenosis of the spinal canal in humans and dogs

Abstract

Acquired stenosis of the spinal canal is a common problem in human and animal pathology. It is defined as a pathological condition that mainly develops as degeneration of the spine with cervical myelopathy development, which is a characteristic manifestation of this pathology. Pain both in the neck and upper back is the leading syndrome of this pathology. 65 human patients aged 20–65 years and 19 dogs weighing more than 20 kg were examined with the aim of comparative clinical and morphometric analysis of stenosis of the spinal canal. The age of the dogs was maximally converted to the age of a person. Computed tomography using the Pavlov-Torg index and the reserve space evaluation supplemented diagnosis of stenosis of the spinal canal. The mass proportion of stenotic changes of the spinal canal against the background of the degenerative-dystrophic process was 21 in males (n = 25) 84.0%, females – 28 persons (n = 40) 70.0%. Pain syndrome was the main complaint in all patients. Cervicalgia prevailed in 60 (92.3%), pain in the upper back was registered in 32 (49.2%) patients. The intensity of pain syndrome was equal to 3.1 ± 0.4 points. Motor deficiency in the form of paresis, mainly of the distal parts of the hands, was registered in 48 patients (73.8%), pyramidal symptoms were noted in the legs in 32 (49.2%) patients, pelvic reservoir dysfunction (7.0–10.8%), and sensory disorders were also found (24.0–36.9%). Such manifestations of cervical myelopathy progressed slowly. Pyramidal symptoms were more frequent and more pronounced in men. According to the computed tomography scan, degenerative changes of the spine were maximal at the level of the C6 vertebra with the maximum clinical correlation (neurological deficit, pain syndrome, etc.). In the course of the research, probable stenosis of the spinal canal was found in people on computed tomography images. In the 19 dogs observed weighing 20 kg or more the presence of pain syndrome was evaluated in all the animals (100.0%) as well as behaviour change (100.0%). During the examination, gait disorder was detected (18.0–94.7%); reaction to palpation of the neck area (15.0–78.9%); the habitus of animals experiencing pain, especially during neck movements (14.0– 73.7%), body tension (12.0–63.1%), etc. Bony outgrowths of the edges of the vertebrae and intervertebral joints were found in almost all dogs of 18 (94.7%) large breeds compared to others. Narrowing of the intervertebral openings, deformation and sclerotic changes of the locking plates, thickening of the yellow and elongated ligaments occurred three to four times more in large breeds compared to dogs weighing less than 20 kg, and were absent in cats. Stenosis of the spinal canal was detected in 15 (78.9%) dogs. Therefore, acquired stenosis of the spinal canal probably develops after degenerative-dystrophic changes in the neck in 87.7% of people and in 78.9% of dogs with clinical manifestations of cervical myelopathy and with persistent pain syndrome (equal to 3.1 ± 0.3 points in humans and 2.6 ± 0.4 points in animals according to visual analog scale). This kind of pathological process in the investigated groups developed mainly at the level of the C6 vertebra. Similar clinical and morphometric indexes were obtained in humans (87.7%). It was found that the maximum similarity of pathological processes with stenosis of the spinal canal formation was characteristic in dogs of exclusively large breeds. Therefore, we consider it promising to study the development mechanisms of stenosis of the spinal canal and peculiarities primarily in young generations of humans and animals, to implement modern non-invasive neuroimaging methods, in particular for animals with investigation of morphometric indexes. This will prevent the occurrence of most comorbid syndromes, including chronic pain, neurological deficits as well as help find new opportunities for correction of stenosis of the spinal canal, to suppress the aging processes not only of the muscle-skeletal system but also of the body as a whole. The importance of this work, we suppose, lies in the further identification of adequate models in animals of different breeds and weight categories with stenosis of the spinal canal pathology in which it develops significantly faster, for extrapolation to humans to predict the development of pathological events.