A transmandibular lateral transsphenoidal navigated surgical approach to access a pituitary macroadenoma in a warmblood mare.
Abstract: A 16-year-old warmblood mare was referred with a progressive history of behavioral changes and left-sided blindness. Following neuroanatomical localization to the forebrain, magnetic resonance imaging of the head revealed a well-delineated, 4.5 cm in diameter, round pituitary mass causing marked compression of the midbrain and optic chiasm. Euthanasia was recommended but declined by the owners. Veterinary specialists and a human neurosurgeon collaboratively prepared for surgical case management. A novel navigated transmandibular lateral transsphenoidal approach was developed to access the region of the sella turcica and practiced on cadaver specimens. The horse was anesthetized and placed in sternal recumbency with the head above the heart line. Using a cone beam computed tomography (CBCT)-coupled navigation system, a navigated pin traversing the vertical ramus of the mandible and the lateral pterygoid muscle was placed in a direct trajectory to the predetermined osteotomy site of the basisphenoid bone. A safe corridor to the osteotomy site was established using sequential tubular dilators bypassing the guttural pouch, internal and external carotid arteries. Despite the use of microsurgical techniques, visualization of critical structures was limited by the long and narrow working channel. Whilst partial resection of the mass was achieved, iatrogenic trauma to the normal brain parenchyma was identified by intraoperative imaging. With consent of the owner the mare was euthanized under the same general anesthesia. Post-mortem magnetic resonance imaging and gross anatomical examination confirmed partial removal of a pituitary adenoma, but also iatrogenic damage to the surrounding brain parenchyma, including the thalamus.
Publication Date: 2024-02-23 PubMed ID: 38393300PubMed Central: PMC10896130DOI: 10.1080/01652176.2023.2300947Google Scholar: Lookup
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- Journal Article
Summary
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A 16-year-old horse underwent a novel surgery to remove a large pituitary tumor causing blindness and behavioral changes. However, due to limitations in visualizing crucial areas during surgery, some normal brain tissue was inadvertently damaged, leading to euthanasia.
Background
- The research focuses on a case of a 16-year-old warmblood mare diagnosed with a pituitary macroadenoma (a large benign tumor) causing health issues including behavioral changes and left-sided blindness. The tumor was located through magnetic resonance imaging (MRI).
- While euthanasia had initially been recommended by the veterinary team, the horse’s owners declined. This led to the exploration of a novel surgical procedure to try and remove the tumor.
Surgical Approach
- In collaboration with a human neurosurgeon, a new ‘transmandibular lateral transsphenoidal’ approach was developed specifically to access the tumor located in the region of the sella turcica, a depression in the sphenoid bone where the pituitary gland is situated.
- This surgical approach was initially practiced on cadaver specimens to ascertain its feasibility and safety.
Surgical Procedure
- The horse was anesthetized and placed in sternal recumbency (lying on its chest) with its head positioned higher than its heart.
- Using a Cone Beam Computed Tomography (CBCT)-coupled navigation system, a path to the tumor was created. To achieve this, a pin, guided by the navigation system, was inserted through the vertical ramus of the mandible (the upwards projecting part of the lower jaw), bypassing several important structures like the guttural pouch and carotid arteries (significant blood vessels).
- Once the path was established, an osteotomy (a surgical operation where bone is cut to redirect it) was conducted on the basisphenoid bone (the bone where the pituitary gland is located) to reach the tumor.
Challenges and Outcome
- Although this innovative method allowed for access to the tumor, it also presented significant challenges. The surgical working channel was long and narrow, making it difficult to visualize key structures.
- While a partial removal of the tumor was successfully accomplished, the procedure resulted in unintended damage to the normal brain tissue. This trauma was identified by intraoperative imaging during surgery.
- Given the damage to the normal brain tissue, and after consulting with the horse’s owner, the decision was made to euthanize the mare under the same general anesthesia.
- A post-mortem MRI and detailed anatomical examination confirmed the partial removal of the pituitary adenoma, as well as the incidental damage to the surrounding brain tissue, including the thalamus (an important part of the brain).
Cite This Article
APA
de Preux M, Precht C, Guevar J, Graubner C, Thenhaus-Schnabel S, Buser L, Lukes A, Koch C.
(2024).
A transmandibular lateral transsphenoidal navigated surgical approach to access a pituitary macroadenoma in a warmblood mare.
Vet Q, 44(1), 1-10.
https://doi.org/10.1080/01652176.2023.2300947 Publication
Researcher Affiliations
- Swiss Institute of Equine Medicine (ISME), Department of Clinical Veterinary Medicine, Vetsuisse-Faculty, University of Bern, Bern, Switzerland.
- Division of Clinical Radiology, Department of Clinical Veterinary Medicine, Vetsuisse-Faculty, University of Bern, Bern, Switzerland.
- Department of Surgery, Small Animal Clinic, Vetsuisse-Faculty, University of Bern, Bern, Switzerland.
- Swiss Institute of Equine Medicine (ISME), Department of Clinical Veterinary Medicine, Vetsuisse-Faculty, University of Bern, Bern, Switzerland.
- Division of Clinical Radiology, Department of Clinical Veterinary Medicine, Vetsuisse-Faculty, University of Bern, Bern, Switzerland.
- Division of Anaesthesiology and Pain Management, Department of Clinical Veterinary Medicine, Vetsuisse-Faculty, University of Bern, Bern, Switzerland.
- Department of Neurosurgery, Lindenhof Hospital, Bern, Switzerland.
- Swiss Institute of Equine Medicine (ISME), Department of Clinical Veterinary Medicine, Vetsuisse-Faculty, University of Bern, Bern, Switzerland.
MeSH Terms
- Horses
- Humans
- Female
- Animals
- Pituitary Neoplasms / surgery
- Pituitary Neoplasms / veterinary
- Adenoma / surgery
- Adenoma / veterinary
- Adenoma / pathology
- Sella Turcica / pathology
- Sella Turcica / surgery
- Iatrogenic Disease / veterinary
- Magnetic Resonance Imaging / veterinary
- Horse Diseases / diagnostic imaging
- Horse Diseases / surgery
- Horse Diseases / pathology
Conflict of Interest Statement
No potential conflict of interest was reported by the author(s).
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