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.
Syringomyelia is a generic term referring to a neurological disorder where a cyst or cavity is formed within the spinal cord. This cyst called syrinx can expand and elongate over time destroying even the spinal cord leading to pain, paralysis and weakness due to the damage caused. Syringomyelia can lead to inability to feel extremes of hot or cold especially in the hands.
Signs and symptoms of Syringomyelia
Syringomyelia symptoms usually develop slowly over time, and symptoms generally may begin between ages 25 and 40. The symptoms could vary depending upon the extent and location of the syrinx in the spinal cord. Pain is the predominant symptom in Syringomyelia as the nerves are directly under pressure. Patients report pain in the neck, upper back, and shoulders. This is referred to as the cape effect of Syringomyelia - pain where a cape is draped over the shoulders.
There could be pain in the chest, stomach or lower back region for those with a syrinx in the thoracic region of the spinal cord. Neuropathic pain is common among Syringomyelia patients and can be very difficult to treat. Many with Syringomyelia may lose strength and develop numbness in their arms and legs. Controlling body temperature, stiff muscles and loss of bladder and bowel control are other challenges of Syringomyelia. There could be a combination of symptoms experienced by each patient. Symptoms begin in young adulthood. Though the signs of the disorder tend to develop slowly, there could be sudden onset of cough and strain. Some people develop a large syrinx without any symptoms. These people become symptomatic suddenly and deteriorate rapidly.
Causes of Syringomyelia
Syringomyelia is a result of something else and not a disease in itself. The most common cause is a Chiari malformation. Syringomyelia can also result from a spinal cord injury such as a car accident or a fall. Post traumatic Syringomyelia can form months or even years after such an injury. Tumor or mass in spinal cord can also result in Syringomyelia.
Although there have been several theories on this, the most recent one states that the cerebellar tonsils act like a piston and beat down the spinal area with every heartbeat. The piston motion forces the cerebrospinal fluid into the spinal cord where it forms a syrinx. However, the reason for the pressure higher inside than outside the fluid does not match CSF.
Diagnosis of Syringomyelia
Spine MRI can show the presence of a syrinx. Usually MRI of the entire spine is done if Chiari malformations are found. CT scan uses a series of X rays to create a detailed view of the spine and spinal cord.
Treatment of Syringomyelia
Most surgeons recommend surgery of some type. While some surgeons recommend surgery anytime there is a syrinx, others monitor the situation with routine MRI and neurological exams. For Chiari related Syringomyelia, surgery will reduce the syrinx, or at least will prevent increase in most cases. Surgery doesn't always effectively restore the flow of cerebrospinal fluid, and the syrinx may remain, despite efforts to drain the fluid from it.
For those with symptoms of an active syrinx, it may eventually lead to paralysis. For the others without symptoms, the future is less clear and uncertain. Surgery can reduce the pressure on the brain and spinal cord, restore the normal flow of cerebrospinal fluid and resolve Syringomyelia.
Draining the syrinx: The doctor will surgically insert a drainage system called a shunt and drain the syrinx. It consists of a tube with a valve that is flexible from the syrinx flowing in the desired direction. One end of the tube is placed in the syrinx and the other is placed in another area of the body such as the abdomen.
Removing the obstruction: In case a tumor or a bony growth is hindering the normal flow in cerebrospinal fluid, surgically removing the obstruction may restore the normal flow and allow fluid to drain from the syrinx.
Correcting the abnormality: In case a spinal abnormality is hindering the flow of cerebrospinal fluid, surgery to correct it, such as releasing a tethered spinal cord, may restore normal fluid flow and allow the syrinx to drain.
Recovery post surgery
This will vary from one individual to another, but will depend largely on whether there is any permanent damage from the syrinx. In some cases it may take years to get better and stronger. Even after successful surgery, the syrinx may take a year to collapse and may not go away completely. Often recovery can be a series of ups and downs, with long periods of improvements punctuated by temporary setbacks.
Post Surgical Care
Follow-up care after surgery is critical as chances are Syringomyelia may recur. Regular examinations with the doctor, including periodic MRIs to assess the outcome of surgery are necessary. The syrinx may grow over time requiring additional treatment. Even after treatment, the syrinx can cause permanent spinal cord and nerve damage.
Bibliography / Reference
Collection of Pages - Last revised Date: January 16, 2019