An anatomical study of the subarachnoid space surrounding the trigeminal ganglion in horses-in preparation for a controlled glycerol rhizotomy in equids.
Abstract: Equine trigeminal-mediated headshaking is a painful neuropathic disorder comparable to trigeminal neuralgia in humans. The selective destruction of pain fibers within the trigeminal ganglion, called rhizotomy, is the surgical treatment of choice for idiopathic trigeminal neuralgia refractory to medical treatment in humans. The human trigeminal ganglion is enclosed by a dural recess called the Meckel's or trigeminal cave, in which the ganglion is surrounded by a cerebrospinal fluid (CSF)-filled subarachnoid space. During glycerol rhizotomy, glycerol is percutaneously injected in this CSF-filled space. Until now, information about the anatomy of the dural recess and the subarachnoid space surrounding the trigeminal ganglion is lacking in horses. The aim of this study was to explore if a CSF-filled subarachnoid space around the trigeminal ganglion exists in horses. Unassigned: Six equine cadaver heads were investigated for CSF accumulation around the ganglion with a 3 Tesla MRI. After anatomical dissection to expose the trigeminal root, a polymer-based radiopaque contrast agent was injected through the porus trigeminus into the subarachnoid space (cisternography). The exact delineation and the volume of the contrast agent accumulation were determined on subsequent micro-computed tomographic scans and segmentation. Finally, the distribution of the contrast agent within the subarachnoid space was examined histologically in three specimens. Unassigned: In all 12 specimens included in this study, the trigeminal ganglion was surrounded by a subarachnoid space forming a trigeminal cistern. The mean volume of the trigeminal cave in this study was 0.31 mL (±SD: 0.11 mL). Distribution of the contrast agent along the peripheral nerves (i.e., ophthalmic, maxillary and/or mandibular nerve) was observed in 7 out of 12 specimens. Unassigned: A subarachnoid space surrounding the trigeminal ganglion exists in the horse and could be targeted for glycerol rhizotomy in horses suffering from trigeminal-mediated headshaking. However, the clinical relevance of contrast agent distribution along the peripheral nerves remains to be assessed.
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The research focused on studying the anatomical structure of the subarachnoid space in horses as a means to prepare for a controlled glycerol rhizotomy treatment for headshaking in equids. The study’s findings show that a subarachnoid space indeed surrounds the trigeminal ganglion in horses and could be targeted for glycerol rhizotomy.
Context and Purpose of Study
The study was centered around a neurological condition in horses known as trigeminal-mediated headshaking, which is akin to trigeminal neuralgia in humans. This condition causes horses distress because it is a painful neuropathic disorder.
In human medicine, when this disorder is unresponsive to medication, a surgical procedure known as rhizotomy is undertaken. This process involves the selective destruction of pain fibres located in a cluster of nerve cells called the trigeminal ganglion.
The human trigeminal ganglion is situated in a fluid-filled space, the cerebrospinal fluid (CSF)-filled subarachnoid space, which is within a cavity (Meckel’s or trigeminal cave). In performing a glycerol rhizotomy, glycerol is injected percutaneously into this space.
Before this study, there was limited knowledge about the structure of both the dural recess, a small cavity or depression, and the subarachnoid space around the trigeminal ganglion in equine anatomy.
The primary aim of the study was to ascertain if there is a CSF-filled subarachnoid space surrounding the trigeminal ganglion in horses.
Research Methodology
The heads of six equine cadavers were used in the study. The researchers explored CSF accumulation surrounding the ganglion using a 3 Tesla MRI.
The cadaver heads went through an anatomical dissection to expose the root of the trigeminal nerve, upon which radiopaque contrast agent was administered into the subarachnoid space.
Researchers used subsequent micro-computed tomographic scans and segmentation to ascertain the exact location and volume of the contrast agent accumulation.
The distribution pattern of the contrast agent within the subarachnoid space was subsequently analyzed histologically in three specimens.
Results of the Research
The research showed that in all 12 tested specimens, the trigeminal ganglion was surrounded by a CSF-filled subarachnoid space, referred to as a trigeminal cistern.
Research demonstrated the average volume of the trigeminal cave was approximately 0.31 mL.
Furthermore, distribution of the contrast agent followed along the peripheral nerves in seven out of 12 samples. These peripheral nerves include the ophthalmic, maxillary and/or mandibular nerve.
Conclusion and Implication of the Study
The study confirmed the existence of a subarachnoid space surrounding the trigeminal ganglion in the horse. This discovery is significant because it means that glycerol rhizotomy can be considered as a potential treatment method for horses suffering from trigeminal-mediated headshaking.
However, the distribution of contrast agent along the peripheral nerves’ clinical relevance is yet to be determined, thus further studies are needed.
Cite This Article
APA
Becker R, Haenssgen K, Precht C, Khoma OZ, Hlushchuk R, Koch C, Kaessmeyer S, de Preux M.
(2024).
An anatomical study of the subarachnoid space surrounding the trigeminal ganglion in horses-in preparation for a controlled glycerol rhizotomy in equids.
Front Vet Sci, 11, 1424890.
https://doi.org/10.3389/fvets.2024.1424890
Department of Clinical Veterinary Medicine, Vetsuisse-Faculty, Swiss Institute of Equine Medicine (ISME), University of Bern, Bern, Switzerland.
Haenssgen, Kati
Division of Veterinary Anatomy, Department of Clinical Research and Veterinary Public Health, Vetsuisse-Faculty, University of Bern, Bern, Switzerland.
Precht, Christina
Division of Clinical Radiology, Vetsuisse-Faculty, University of Bern, Bern, Switzerland.
Khoma, Oleksiy-Zakhar
Institute of Anatomy, University of Bern, Bern, Switzerland.
Hlushchuk, Ruslan
Institute of Anatomy, University of Bern, Bern, Switzerland.
Koch, Christoph
Department of Clinical Veterinary Medicine, Vetsuisse-Faculty, Swiss Institute of Equine Medicine (ISME), University of Bern, Bern, Switzerland.
Kaessmeyer, Sabine
Division of Veterinary Anatomy, Department of Clinical Research and Veterinary Public Health, Vetsuisse-Faculty, University of Bern, Bern, Switzerland.
de Preux, Mathieu
Department of Clinical Veterinary Medicine, Vetsuisse-Faculty, Swiss Institute of Equine Medicine (ISME), University of Bern, Bern, Switzerland.
Conflict of Interest Statement
The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.
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