Laminectomy is a surgical procedure to remove a portion of the vertebral bone. This is done to relive the pressure on the nerve roots. The lamina is the vertebral bone that is operated upon so as to reduce pressure on the spinal cord and nerve roots. Spinal stenosis usually affects older persons due to degeneration and subsequent enlargement of the facet joints. This leads to acute pain. Laminectomy is also performed to treat conditions such as herniated disks and spondylolisthesis. A patient may need to spend a few days in the hospital and will require physio therapy for embarking on activities such as sitting, standing and walking. In some cases there can be complications such as nerve damage, spinal fluid leak, worsening back pain and bleeding.
Chiari malformations or CM are structural defects in the cerebellum. The cerebellum and parts of the brain stem rest in an indented space at the lower rear region of the skull. This is situated above a funnel-like opening (called the foramen magnum) to the spinal cord. When a part of the cerebellum is found located below the foramen magnum, it is called Chiari malformation.
Causes of Chiari malformations
When the bony space is smaller than normal, this causes the cerebellum and brain stem to be pushed downward into the foramen magnum and into the upper spinal canal, thereby blocking the flow of cerebrospinal fluid that surrounds and cushions the brain and spinal cord.
It can also be caused by structural defects in the brain and spinal cord during fetal development due to genetic mutations or lack of proper vitamins or nutrients in the maternal diet. This is called primary CM or congenital CM.
It is also caused later in life if the spinal fluid is drained excessively from the lumbar and thoracic areas of the spine due to injury or infection. This is acquired CM or secondary CM. However, primary is more common than secondary CM.
Types of Chiari malformations
They are classified into different types depending upon the severity of the disorder.
Type 1 involves extension of the cerebellar tonsils in the foramen magnum involving brain stem. This commonly occurs in adolescence or adulthood.
Type II is called classic CM and it involves extension of both cerebellar and brain stem tissue into the foramen magnum.
Type III is the most serious form of CM. Here the cerebellum and brain stem protrude or herniate through the foramen magnum and into the spinal cord.
Type IV involves an incomplete or underdeveloped cerebellum, a condition known as cerebellar hypoplasia. This is a rare form of CM.
There is yet another form of this disorder which some researchers call as Type 0, in which there is no protrusion of the cerebellum through the foramen magnum but headache and other symptoms are present.
Neck pain, balance problems, muscle weakness, numbness and other abnormal feelings in arms and legs, dizziness, vision problems, difficulty in swallowing, buzzing in the ears, hearing loss, vomiting, insomnia, depression or headache made worse by coughing or straining are some common symptoms.
Symptoms may change from one person to another depending upon the degree of CSF buildup. Patients with type I CM may not have symptoms at all. Adolescents and adults who have CM but no symptoms initially may later in life develop symptoms such as difficulty in swallowing, irritability when being fed, vomiting, arm weakness, a stiff neck, breathing problems, developmental delays and inability to gain weight.
CM is also sometimes associated with certain hereditary syndromes that affect neurological and skeletal abnormalities and disorders that affect bone formation and growth.
It is estimated that the condition occurs in about one in every 1000 births. However, increased use of diagnostic imaging has shown that CM may be much more common. CM occurs more often in women than in men and Type II malformations are more prevalent in certain groups including people of Celtic descent.
As many exhibit no symptoms, their malformations are discovered only during the course of diagnosis or treatment for another disorder. The doctor performs a physical exam and checks the person's memory, cognition, balance, touch, reflexes, sensation and motor skills.
X ray of the head and neck is done to produce images of bones and certain tissues. Though these cannot reveal a CM, they can identify abnormalities that are associated with CM. a and MRI are most often suggested..
Some CMs are asymptomatic and do not interfere with a person's daily activities of daily living and in some cases, medications are used to ease certain symptoms including pain.
Surgery is the treatment option to correct functional disturbances or halt the progression of damage to the central nervous system. Surgery can help reduce symptoms. More than one surgery may be needed to treat the condition. There are different types of surgery performed on adults with CM to create more space for the cerebellum and to relieve pressure on the spinal column.
Surgery involves making an incision at the back of the head and removing a small portion of the bottom of the skull to correct the irregular bony structure. This surgical technique involves destroying tissue with high-frequency electrical currents. Spinal Laminectomy involves surgical removal of the arched, bony roof of the spinal canal to increase the size of the spinal canal and relieve pressure on the spinal cord and nerve roots.
Sometimes, the surgeon makes an incision in the dura to examine the brain and spinal cord. Additional tissue may be added to the dura to create more space for the flow of CSF. Infants may require surgery to reposition the spinal cord and close the opening in the back.
Hydrocephalus is treated with a shunt system that drains excess fluid and relieves pressure from the head. An alternative surgical treatment to improve the flow of CSF is by making a small perforation in the floor of the third ventricle and the CSF is diverted to relieve pressure. Surgeons may open the spinal cord and insert a shunt to drain a syringomyelia. A small catheter is inserted into the syrinx for continued drainage.
Post surgery follow-up
Since surgery involves risk, including the possibility of infection, fluid in the brain, cerebrospinal fluid leakage or problems in wound healing, it is recommended to discuss the pros and cons with the doctor when deciding whether surgery is necessary or not. Surgery reduces symptoms in most people but if nerve injury in the spinal cord has already occurred then this procedure will not reverse the damage. Regular follow up post surgery with examinations by the doctor and periodic imaging tests to assess the outcome of surgery and flow of cerebrospinal fluid is essential.
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Bibliography / Reference
Collection of Pages - Last revised Date: July 30, 2021