Neurosurgery

At Veterinary Specialists of Rochester we handle many patients with a variety of disorders of the nervous system. We also work in conjunction with a local, board-certified veterinary neurologist to provide the greatest expertise with the most challenging cases. Neurological problems can be subdivided into those that affect the central nervous system (CNS), which includes the brain and spinal cord, and the peripheral nervous system (PNS), which includes nerves to the arms (forelimbs) and legs (hindlimbs). Along with the peripheral nervous system proper (the nerves themselves) we and the neurologist also see, evaluate and treat patients with diseases of the neuromuscular junction and the muscles themselves (in many patients it can be challenging to distinguish the exact location – nerve, neuromuscular junction, or muscle – where the disease is). Among these diseases are polymyopathy, polymyositis, polyneuropathy, polyneuritis, and myasthenia gravis.

Because most of the nervous system is inaccessible for direct examination, diagnosis of neurological problems depends on obtaining a good history, consideration of the species, breed, age and gender of the patient, and conducting a thorough neurological examination in order to establish an idea of localization – where in the nervous system the problem lies – and differential diagnosis – a list of the likeliest causes for the observed signs/symptoms. Armed with these deduced concepts specific tests may then be recommended to confirm or refute the findings, and to guide treatment and prognosis.

In animals with suspected peripheral nervous system/muscle disease tests may include looking at blood samples for specific markers (some tests are done in-house in our own Veterinary Laboratory of Rochester, while others, through our lab, are sent to appropriate laboratories around the country for specialized tests), and may also involve referral to a board-certified veterinary neurologist for electrodiagnostic tests such as electromyography (EMG) or nerve conduction velocity (NCV). Such patients may also require biopsies of nerves and muscles, and may need radiographs (x-rays) to evaluate such things as esophageal function (diseases that affect peripheral nerves and muscles frequently can affect swallowing muscles as well).

Most of the patients seen at Veterinary Specialists of Rochester for neurological disease have disorders affecting the central nervous system. Among the common diseases we contend with are intervertebral disc disease, tumors, brain and spinal cord trauma, brain or spinal cord vascular diseases, spinal malformations and instability syndromes (including so-called “Wobbler’s Syndrome”), and various inflammatory or infectious diseases of the CNS.

Intervertebral disc disease is the most common cause for animals to be presented for neck or back pain and possibly weakness or paralysis of one or more limbs. Unfortunately it is not always possible to discern the cause for such signs simply by observing the patient, since many different diseases can look similar in terms of the symptoms the patient has. For this reason, if it is determined that medical therapy alone is insufficient for treatment, and surgery is thought to be a possible solution, imaging studies will likely be required to determine the precise location and nature of the causative problem. Diagnostic imaging for spinal cord disorders involves either myelography (where a radiological contrast agent – dye – is injected into the spinal fluid to permit visualization of the otherwise radiographically-invisible spinal cord on x-rays), computed tomography (CT; sometimes combined with myelography), and magnetic resonance imaging (MRI). The latter is generally the best way of obtaining diagnostic pictures of the spinal cord, but may not always be available in hyperacute, emergency situations.

Similarly, spinal cord tumors are frequently managed with surgery where appropriate. Like intervertebral disc disease, advanced imaging (MRI in most cases) will be used to provide precise guidance to the surgeon.

Inflammatory diseases of the CNS may require a spinal tap and cerebrospinal fluid (CSF) analysis in addition to possible imaging for diagnosis. These diseases are usually treated with non-surgical means.

Disorders involving the brain are also best characterized with advanced imaging techniques, either MRI or CT. The former generally provides better pictures and more complete elucidation, but is more costly than CT and requires more time under sedation/anesthesia. If advanced imaging is required for your pet the doctor will discuss the rationale for selecting one modality over the other.

Intervertebral disc disease and tumors of the central nervous system are the most common indications for neurosurgery at Veterinary Specialists of Rochester. Surgery is also used in some patients that have sustained spinal cord trauma resulting from fracture/luxation (dislocation) of a portion of the spine and resultant pain and/or paralysis (broken neck or back), and also some of the various malformation/instability syndromes including “Wobbler’s Syndrome.” The goal behind all such procedures is to attempt to restore neurological function back to normal and alleviate pain and suffering. As with humans that sustain brain or spinal cord problems, the completeness of recovery and time required can be variable, and may require a period of physical therapy/rehabilitation beyond surgery itself.

One thing to keep in mind regarding “disc disease”: Although many of us, or others we know may suffer from “disc problems,” there are some differences between humans and dogs (and cats). While the syndromes associated with cervical (neck) disc problems are virtually identical, those involving the back are quite different. Most humans with disc problems in their back have involvement of the low back. In humans the spinal cord ends at about the level of the bottom of the rib cage, so that these low back disc problems result from pressure on nerve roots in the spinal canal rather than pressure on the spinal cord itself. In dogs and cats however the spinal cord continues to almost the level of the last lumbar vertebra, so disc problems at all but the very last one or two levels involve direct injury to the spinal cord. For this reason disc problems in dog and cats are frequently a more severe problem than in humans, often require emergency care, and more commonly require surgery for successful resolution.

There are different surgical approaches used for spinal cord diseases, the choice being made by the nature and location of the causative problem. The spine may be approached surgically from the rear (posterior in humans; dorsal in quadrupeds like dogs and cats) through the upper part of the bony spinal canal termed the lamina. These procedures are collectively called “laminectomies”. If only one side of the lamina is removed during surgery it is termed a “hemilaminectomy.” Other procedures and terms frequently encountered during these dorsal approaches include facetectomy, pediculectomy, and foramenotomy. Each refers to a different part of the anatomy of the vertebra that may be opened to afford room for the surgeon to operate or to achieve decompression of the spinal cord and the nerve roots that branch off the spinal cord. In the neck, the spinal cord can be approached dorsally as above but also from the front (anterior in humans; ventral in quadrupeds like dogs and cats). The latter may be advantageous in some cases because it entails less muscle dissection and trauma, and also because for problems like many ruptured discs, the material that needs to be removed to achieve the goal of spinal cord decompression lies in the front – ventral – to the spinal cord. This procedure is referred to as a “ventral slot.” Except for certain non-disc-related diseases, it is not usually necessary to perform spinal fusions on animals as is commonly done in humans with disc surgery. However, spinal fusions are used for some of the instability syndromes of the neck and back, including “Wobbler’s Syndrome.”

For selected patients with brain disease surgery may play a role in treatment. Certain tumors may be amenable to surgical removal, and some dogs have malformations of the opening at the back of the skull (foramen magnum) for which surgery can alleviate symptoms (Chiari malformation or Caudal Occipital Malformation Syndrome – COMS). On occasion dogs with certain forms of hydrocephalus (“water on the brain”) may be treated with shunts that allow cerebrospinal fluid to drain from the cranium to another location in the body. Although problems such as subdural hematomas after trauma or stroke are far less common in dogs and cats than humans, there are occasions where surgery to relieve pressure from hematomas (large blood clots) or depressed skull fractures can be utilized to improve an animal’s prognosis.

In addition to post-operative physical therapy and rehabilitation to help restore function after surgery, some patients may benefit from other adjuvant treatments. This may include certain drugs and in some instances radiation therapy.