Neurosurgery at theVSCAN
Neurosurgery Involving Conditions of the Brain:
A craniotomy is a procedure that involves creating an entry into the skull to access the structures within the cranium such as the brain, meninges, ventricular system, and nerve roots. Conditions that require a craniotomy procedure may involve surgical removal of brain tumors, brain biopsies, relieving hemorrhage, or compression due to a foreign body or trauma. Depending on the location of the condition where the access needs to be created, the approach of the craniotomy procedure varies. Craniotomies need to be carefully and diligently planned. Planning involves advanced imaging such as magnetic resonance imaging (MRI) of the brain and usually in conjunction with computed tomography (CT).
Chiari-like Malformation and Foramen Magnum Decompression
The anatomy of certain breeds such as the Cavalier King Charles Spaniel and Brussels Griffon predispose them to a condition called Chiari-like Malformation. This is a condition in which the shortening of the soft palate of the mouth and the malformation of the occipital bone at the back of the skull in combination results in inadequate space within the back part of the skull. Due to inadequate space, brain structures residing at the back of the skull, namely the cerebellum, are compressed and this results in herniation of a part of the cerebellum out towards the back of the skull. This condition is also associated with the blockage of cerebrospinal fluid (CSF) flow from the ventricular system within the brain towards the spinal cord. When the natural flow of CSF is obstructed, this fluid builds up within the ventricular system causing the ventricular system to dilate and push onto structures of the brain. In addition, fluid also accumulates abnormally within the spinal cord, a condition called syringohydromyelia, and causes abnormal sensation or pain in the neck and/or back. The common symptoms of Chiari-like Malformation are neck pain, phantom scratching of the neck, loss of balance that may be episodic, and even seizures. A MRI of the brain is required to accurately diagnoses this condition.
If a patient is a candidate for surgical remedy, a procedure called a foramen-magnum decompression is performed. In this procedure, a section of the occipital bone that is compressing onto the cerebellum is removed, along with a section of the atlas, the first cervical vertebra. This allows for the cerebellum to be decompressed and then establishes an improved flow of CSF, thus preventing further building of CSF within the ventricular system and the spinal cord. The goal of the surgery is to relieve/improve clinical signs and prevent further decline.
Ventriculoperitoneal Shunt Placement
This particular procedure involves placement of a tube to shunt cerebrospinal fluid (CSF) away from the brain and into the abdomen to be absorbed. This procedure is employed when there is a buildup of CSF either within the ventricular system or if there is formation of an abnormal cystic structure called an intracranial arachnoid cyst.
Neurosurgery Involving Conditions of the Spine:
Intervertebral Disk Disease
The intervertebral disk acts as a shock absorber of the spinal column located between the vertebral bones, and under the spinal cord. Each intervertebral disk is a structure that consists of an outer fibrous capsule called the annulus fibrosus which houses in its center, a gelatinous substance called the nucleus pulposus. Intervertebral disk disease occurs when structures of the disk protrude, extrude, or push onto the spinal cord and/or nerve roots, resulting in pain and neurologic disability. Depending on the location, and extent of the compression, several approaches may be employed to decompress the spinal cord and nerve roots. These procedures include:
Distraction / stabilization
Wobbler’s disease / Caudal cervical spondylomyelopathy
Large breed dogs such as Doberman Pinschers, Great Danes, and even German Shepherd dogs may suffer from compression of the lower neck, resulting in neurologic dysfunction and pain. The compression can arise from instability, enlargement of articular joint facets of the vertebrae, intervertebral disk degeneration and protrusion, or thickening of ligaments. An MRI of the neck is required to determine the underlying cause of instability and compression. Should instability due to dynamic movement of the neck be suspected, dynamic views during MRI can be performed. Based on that information the surgical approach can be planned.
Several conditions of the spine such as atlantoaxial (AA) subluxation and hypoplastic articular facets may benefit from surgical stabilization procedures. A combination of survey radiographs, magnetic resonance imaging (MRI), and computed tomography (CT) are required to obtain appropriate information for surgical planning to fixate the instability and finally, a radiograph or CT is performed to confirm appropriate placement of implants.
Trauma can cause severe damage to the vertebral bones and spinal cord. Survey radiographs, magnetic resonance imaging (MRI), and computed tomography (CT) are required to obtain appropriate information for surgical planning to fixate a spinal fracture. Post surgically, another CT would be performed to ensure that the reduction of the fracture and placement of surgical implants are appropriate.
Depending on the extent and location of tumors affecting the spinal cord, patients can be candidates for surgical removal. Such procedures are normally described as decompression and cytoreduction, meaning the goal of the surgery is to remove as much of the tumor as possible to reduce compression in order to prevent further decline and possibly even improve function. Tumor removal in surgery is usually incomplete and some tumor is usually left behind. Therefore, the goal of the surgery is also to obtain tissue for submission to a laboratory to identify the tumor. Once the tumor is identified, recommendations for oncologic treatment can be made by an oncologist. Tumors encountered affecting the spinal cord are often meningiomas and nerve sheath tumors.
Neurosurgery Involving Conditions of the Nerves and Muscles:
Nerve Sheath Tumor
This particular tumor arising from around the nerve can compress or enlarge the nerve resulting in pain, lameness, and compress onto the spinal cord. Based on its location, surgical removal of the tumor, followed by radiation therapy may be recommended.
Muscle and Nerve Biopsy
Disorders of the neuromuscular junction usually require electrodiagnostic workup. Based on findings of electrodiagnostic studies and possibly imaging, nerve and muscle biopsies can be obtained and the tissue samples submitted to a laboratory for testing.