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Chiari Decompression

What is Chiari Decompression?

Chiari decompression is a surgical treatment for an abnormal brain condition called Chiari malformation, also known as Arnold Chiari malformation, in which the brain tissue protrudes into the spinal canal at the back of the skull. This occurs as a result of a structural problem in the skull, where a section of the skull is malformed or abnormally small, pressing on your brain and forcing it downward. The disorder may be present at birth or may develop as the brain and skull grow.

Chiari decompression surgery is also known as posterior fossa decompression surgery and involves removal of a small section of bone at the back of the skull called the posterior fossa to create more space for the brain tissue and relieve pressure on the brain.

Indication for Chiari Decompression Surgery

Chiari malformation affects the part of your brain known as the cerebellum. It is situated behind the brainstem, where the spinal cord meets the brain. When the cerebellum pushes into the spinal canal it can obstruct signals from the brain to the body as well as cause accumulation of cerebrospinal fluid (CSF) in the brain or spinal cord. This can trigger a variety of neurological symptoms such as:

  • Speech and vision problems
  • Tingling and numbness of the feet and hands
  • Dizziness
  • Neck pain
  • Headache
  • Hearing loss
  • Difficulty swallowing
  • Upper body weakness
  • Loss of sensation of pain or temperature

Chiari decompression surgery is indicated for the resolution of these symptoms which can significantly interfere with your activities of daily living.

Preparation for Chiari Decompression Surgery

Pre-procedure preparation for Chiari decompression surgery may involve the following steps:

  • A thorough examination is performed by your doctor to check for any medical issues that need to be addressed prior to surgery.
  • Depending on your medical history, social history, and age, you may need to undergo tests such as blood work and imaging to help detect any abnormalities that could threaten the safety of the procedure.
  • You will be asked if you have allergies to medications, anaesthesia, or latex.
  • You should inform your doctor of any medications, vitamins, or supplements that you are taking.
  • You may need to refrain from supplements or medications such as blood thinners or anti-inflammatories for a week or two prior to surgery.
  • You should refrain from alcohol or tobacco at least a week before surgery.
  • You should not consume any solids or liquids at least 8 hours before surgery.
  • You will be instructed to shower with an antibacterial soap the morning of surgery to help lower your risk of infection.
  • You need to take off any jewellery, clothing, or other objects that may obstruct the procedure and wear a hospital gown.
  • Arrange for someone to drive you home after surgery.
  • A written consent will be obtained from you after the pros and cons of the surgery have been explained in detail.

Procedure for Chiari Decompression Surgery

Procedure for Chiari decompression surgery generally involves the following steps:

  • You will lie face down on the operating table under the influence of general anaesthesia.
  • The treatment area on the head will be shaved along the planned incision and the surgical site is cleaned with an antiseptic solution.
  • The head is placed in a 3-pin skull-fixation device that is attached to the operating table to hold your head in position until the end of the surgery.
  • A 3-inch surgical cut is made down the middle through the neck muscles so that your surgeon can visualise the skull and top of the spine. 
  • The neck muscles and soft tissues are retracted, and the treatment area is exposed for the surgery.
  • Your surgeon then removes a small part of the skull at the back of your head (foramen magnum). This is referred to as a suboccipital craniectomy. Most often your surgeon also removes the bony arch of the first two vertebrae, C1-C2, to the point where the cerebellar tonsils end. This is referred to as a laminectomy. These steps provide more room for the brainstem, spinal cord, and cerebellar components.
  • Next, your surgeon may also open and widen the dura (the protective covering of the brain and spinal cord tissues) to create additional room for the cerebrospinal fluid to circulate and to enlarge the covering to provide more room for your brain.
  • A tissue graft is often interwoven into the opening made by your surgeon to provide even more space for the unrestricted passage of cerebrospinal fluid.
  • Finally, the retracted muscles and soft tissues are placed in their normal positions and the wound is sutured closed.

Postoperative Care and Recovery

In general, postoperative care instructions and recovery after Chiari decompression surgery may involve the following:

  • You will be transferred to the recovery area where your nurse will closely observe you for any allergic/anaesthetic reactions and monitor your vital signs as you recover.
  • Most patients may need to stay in the hospital for 2 to 3 days before discharge to home.
  • You may experience pain, inflammation, and discomfort in the operated area. Pain and anti-inflammatory medications are provided as needed.
  • Walking and moving around in bed is strongly encouraged to prevent the risk of blood clots.
  • Keep the surgical site clean and dry. Instructions on surgical site care and bathing will be provided.
  • Refrain from smoking and alcohol for a specific period of time as it can negatively affect the healing process.
  • Refrain from lifting anything heavier than 5 pounds and other strenuous activities until the first follow-up visit. These activities may include housework, yard work, gardening, mowing, etc.
  • Gentle neck stretches and regular walking is recommended to improve strength and endurance after the first follow-up visit.
  • Refrain from driving until you are fully fit and receive your doctor’s consent.
  • Most patients can return to their normal daily routines in 3 to 4 weeks after surgery.
  • A periodic follow-up appointment will be scheduled to monitor your progress.

Risks and Complications

Chiari decompression surgery is a relatively safe procedure; however, as with any surgery, some risks and complications may occur, such as:

  • Infection
  • Bleeding
  • Blood clots
  • Anaesthetic/allergic reactions
  • Neurovascular injury
  • Persistent pain
  • Cerebrospinal fluid leakage
  • Permanent disability due to brain or nerve damage
  • King's College London
  • Stanford University
  • University of Pittsburgh Medical Center
  • The Royal College of Surgeons of England