Brain and Spinal Surgery
A hemilaminectomy is the most common surgical approach in the thoracolumbar spine. The approach is less commonly used in the cervical spine. The surgical approach for a hemilaminectomy is from the top side of the dog or cat. Once the spinal column is reached, portions (lamina and pedicle ) of the vertebrae are removed from the side. This allows for removal of disc that has herniated off to one side or the other or removal of a tumor or cyst that may be located on one side of the spinal cord. This approach also allows direct access to the disc that lies underneath the spinal cord. It allows for greater access to the spinal canal compared to a ventral slot and allows probing (NOTE: definitely can't see beneath the cord, that's what makes surgeries hard) beneath the spinal cord which is difficult to obtain during a dorsal laminectomy. Once the portion of the vertebrae is removed during a hemilaminectomy the herniated or ruptured disc material is then removed with small instruments. The combination of the hemilaminectomy approach and disc material removal alleviates compression or pinching the spinal cord allowing further spinal cord healing to take place. During the hemilaminectomy procedure the disc
is not replaced. Fenestration of the affected disc and sometimes the nearby discs may be done depending on the clinical scenario and surgeon preference to try to prevent future herniation at those sites. Potential complications from hemilaminectomy include trauma to the spinal cord, hemorrhage, infection and instability. The prognosis with the hemilaminectomy procedure is often good, but depends on the pre-surgical condition of the pet. Dogs and cats with acute disc herniation that have the ability to feel their toes at the time of surgery typically do quite well. The success rate with surgery is less for dogs without sensation of their toes, chronic spinal cord compression and multiple compressive sites. Recovery time is variable with return to ambulation typically within weeks to months. Strict rest/confinement is recommended for about 1 month post-surgery with gradual increase in activity thereafter. During confinement a well-padded surface is recommended to prevent bed sores. It is important to ensure that your pet is urinating regularly post operatively. Urinary tract infections are common in dogs with spinal cord injury and should be monitored for. Rehabilitation therapy can assist recovery (recent study showed rehab doesn't actually affect outcome).
Ventral Slot Surgery
The surgical approach for removal of a herniated disc depends upon the location of the disc material within the spinal canal. A ventral slot procedure is the most common surgical procedure for disc herniation in the cervical spine. The approach is from the underside (ventral) of the neck, where intervertebral discs are located. A small hole (slot) is drilled through the center of the disc and a small portion of the adjacent vertebrae. This allows access to the spinal canal at the location of the herniated disc. Small instruments are then used to remove any free fragments of disc material that have herniated or ruptured into the spinal canal.
When indicated surgical success with a ventral slot procedure is good, provided that the disc herniation is acute and that neurological function is adequate at the time of surgery (removed thing about pain sensation; prognosis more variable for necks than backs and only about 80% that are done recover with abotu 20 - 25% death/euthanasia rate in down neck dogs). Potential complications include hemorrhage, post-operative infection, instability/subluxation, respiratory failure/need for mechanical ventilation and spinal cord trauma. Fusion is not typically done with routine disc herniations, as dogs do well without it and the disc space will partially fuse within a few months post operatively.
Recovery depends on the initial neurological status with return of ambulation within days to months. Strict rest/confinement is recommended for about 1 month post surgery with gradual increase in activity thereafter. During confinement a well-padded surface is recommended to prevent bed sores. Rehabilitation therapy can speed recovery.