Untersuchung auf ein mögliches Vorkommen von geringgradigen lagerungsbedingten iatrogenen Nervenschäden beim Kleintier im Katzenmodell

Positioning dependent neurological injuries present a well-known aetiological factor in human medicine with serious negative consequences for the patient. In animals, iatrogenic nerve injuries caused by inappropriate perioperative positioning are well described in large animals, but evidence-based information about the existence of this issue in small companion animals is missing. This cumulative dissertation consists of a foundational and applied research part. 1) The goals of the foundational research part were: - Selection of the appropriate small animal model; - Standardisation of the positioning and fixation methodologies; - Evaluation and quantification of the anatomical changes of the spinal column during perioperative positioning in the animal model as a basis for the further clinical study; - Determination of the more physiological perioperative position from an anatomical point of view. European Shorthair cats with feline lower urinary tract disease (FLUTD) undergoing perineal urethrostomy were selected as an animal model. The positioning and fixation methodologies were standardised. Twenty-one male feline cadavers were enrolled in the study. All feline cadavers were evaluated by CT. Examinations were performed with the cadaver in a neutral position and dorsal and ventral recumbency. Sagittal vertebral canal diameters (VCDs) were obtained by measuring the distance between the ventral and dorsal aspects of the vertebral canal in the middle of the intervertebral space. A comparison of the VCDs between L6 and L7, L7 and S1, S3 and Co1 and Co1 and Co2 in neutral position vs dorsal recumbency revealed a reduction of 0.27 mm (14.6%; P <0.001) between S3 and Co1 and 0.26 mm (18.1%; P <0.001) between Co1 and Co2. No differences were seen when comparing L6–L7 and L7–S1. The VCDs were decreased in all segments when comparing neutral with ventral recumbency. This study revealed a reduction of 0.13 mm between L6 and L7 (3.3%; P = 0.003), 0.14 mm between L7 and S1 (4.1%; P = 0.003), 0.61 mm between S3 and Co1 (32.5%; P <0.001) and 0.63 mm between Co1 and Co2 (44.1%; P <0.001). Comparison of the VCD between dorsal and ventral recumbency in L6–L7, L7–S1, S3–Co1 and Co1–Co2 revealed a decrease in the VCDs in ventral recumbency of 0.13 mm (3.3%; P <0.001), 0.12 mm (3.6%; P <0.001), 0.34 mm (21.0%; P <0.001) and 0.37 mm (31.7%; P <0.001), respectively. The results provide evidence that, from an anatomical point of view, perineal urethrostomy performed in dorsal recumbency is superior to ventral recumbency, but further clinical study to verify these findings was needed. 2) The goals of the applied research part were: - Evaluation and quantification of the postoperative neurological changes associated with the perioperative positioning in the animal model and the determination of the existence or non-existence of positioning dependent nerve injury; - Determination of the more physiological position from a clinical point of view. Twenty male castrated cats with FLUTD presented for perineal urethrostomy were enrolled in this study. Surgery was performed either in dorsal (group A) or in ventral recumbency (group B). Motor response of the patellar tendon, gastrocnemius muscle, pelvic limb withdrawal and perineal reflex, as well as the presence of spinal pain in the lumbosacral region, motor function of the tail and faecal continence were examined prior to surgery, 24 hours and 14 days after surgery. The mean weight of animals was 5.07 ± 1.08 kg with a mean age of 6.12 ± 1.85 years. Weight and age were not significantly different between groups A and B (both P = 0.897). All tested parameters of the neurological examination performed prior to surgery were considered normal in both groups (P = 1). The comparison between neurological examinations (perineal reflex and spinal pain) before and 24 hours after surgery revealed a significantly decreased briskness of the perineal reflex and an increased occurrence of spinal pain 24 hours after surgery (P = 0.043 and P = 0.031, respectively). However, the changes of aforementioned parameters were statistically insignificant (P = 0.249, P = 0.141) between groups A and B. The other parameters (patellar tendon, pelvic limb withdrawal and gastrocnemius muscle reflexes; motor function of the tail and faecal continence) were statistically insignificant (P = 1) before surgery and 24 hours after surgery, as well as between groups A and B 24 hours after surgery. Results of all tested parameters were statistically insignificant (P = 1) before surgery and 14 days after surgery, as well as between groups A and B 14 days after surgery. The briskness of the perineal reflex was significantly decreased and the occurrence of spinal pain significantly increased 24 hours after surgery. A parallel with a low-grade positioning dependent nerve injury as described in human medicine may be drawn. However, no fixation method has been proven to be superior to the other.Lagerungsbedingte neurologische Schäden sind in der Humanmedizin wohlbekannte ätiologische Faktoren mit ernstzunehmenden Konsequenzen für den betreffenden Patienten. Beim Großtier sind iatrogene Nervenschäden durch inadäquate Positionierung des Patienten peri operationem gut beschrieben, evidenzbasierte Daten zu ihrem Vorkommen beim Kleintier fehlen jedoch. Diese kumulative Dissertation besteht aus einem Grundlagen- und angewandten Forschungsteil. 1) Ziele des Grundlagenteils waren: - die Auswahl eines geeigneten Kleintiermodells; - die Standardisierung der Positionierung und der Fixationsmethoden; - die Evaluation und Quantifizierung anatomischer Veränderungen im Bereich der Wirbelsäule während der perioperativen Lagerung im Tiermodell als Basis für die weiterführende klinische Studie; - festzustellen, welche Art der perioperativen Positionierung aus anatomischer Sicht eher als physiologisch anzusehen ist. Als Tiermodell wurden Europäisch Kurzhaarkatzen mit Feline Lower Urinary Tract Disease (FLUTD) gewählt, bei denen eine perineale Urethrostomie durchgeführt wurde. Die Positionierung und Fixationsmethoden wurden standardisiert. Einundzwanzig Kadaver männlicher Katzen wurden in diese Studie eingeschlossen. Alle Katzenkadaver wurden mittels Computertomographie (CT) untersucht. Die Untersuchungen der Kadaver wurden in Neutralposition sowie in Rücken- und Bauchlage durchgeführt. Die sagittalen Diameter des Wirbelkanals (VCDs) wurden durch Messung der Abstände zwischen ventralem und dorsalem Rand des Wirbelkanals mittig auf Höhe der Intervertebralspalten ermittelt. Ein Vergleich der VCDs zwischen L6 und L7, L7 und S1, S3 und Co1 sowie Co1 und Co2 in Neutralposition und Rückenlage ergab eine Reduktion des VCDs um 0,27 mm (14,6%; P <0,001) zwischen S3 und Co1 sowie um 0,26 mm (18,1%; P <0,001) zwischen Co1 und Co2. Es wurde kein Unterschied beim Vergleich der VCD’S zwischen L6 und L7 sowie L7 und S1 festgestellt. Die VCD’S waren beim Vergleich von Lagerung in Neutralposition und Lagerung in Bauchlage in allen untersuchen Wirbelsäulenabschnitten reduziert. Zwischen L6 und L7 um 0,14 mm (3,3%; P = 0,003), zwischen L7 und S1 um 0,14 mm (4,1%; P = 0,003), zwischen S3 und Co1 um 0,61 mm (32,5%; P <0,001) und zwischen Co1 und Co2 um 0,63 mm (44,1%; P <0,001). Ein Vergleich zwischen Lagerung in Bauch- und Rückenlage ergab ebenfalls eine Reduktion der VCD’S in Bauchlage in den Abschnitten L7, L7–S1, S3–Co1 und Co1–Co2 von jeweils 0.13 mm (3.3%; P <0.001), 0.12 mm (3.6%; P <0.001), 0.34 mm (21.0%; P <0.001) und 0.37 mm (31.7%; P