CSF Shunt Surgery
Listed below is the step by step procedure of CSF shunt surgery:
- What is CSF Shunt Surgery?
- Why is CSF Shunt Surgery Required?
- Pre-operative Preparation
- Day Before Surgery
- Procedure Day
- Methods/Techniques of CSF Shunt Surgery
- Post Procedure
- Risks and Complications
What is CSF Shunt Surgery?
A shunt is a device that can divert something from its mainstream, example in railways or in electrical circuits. Similarly, a brain shunt is a piece of narrow tubing that diverts the excess buildup of fluid in its compartments to other parts of the body.
Cerebrospinal fluid (CSF) is the shock- absorber of the brain which protects it from injuries, also provides it nutrition and immunity. Excess fluid (CSF) buildup in the brain increases the intracranial pressure which can lead to development of severe neurological deficiencies.
To prevent these problems from worsening, a CSF shunt is placed in the ventricle (a communicating cavity in the brain) and some of the CSF is diverted to other parts of the body to relieve the brain of extra pressure.
Why is CSF Shunt Surgery Required?
To put it simply, anyone suffering from a condition which causes an increase in the intra-cranial pressure or excess CSF buildup, will be considered as a candidate for CSF shunt surgery.
Here is a list of conditions that may require C shunt surgery as treatment
- Hydrocephalus: It is the abnormal accumulation of cerebrospinal fluid in the brain, leading to increase in the intracranial pressure. Few types are considered here
- Congenital Hydrocephalus: Genetic abnormalities that increase the fluid content in the brain.
- Post-Hemorrhagic Hydrocephalus: This is bleeding into the brain cavities (ventricles) that blocks the flow of CSF.
- Normal-Pressure Hydrocephalus: The lateral cerebral ventricles expand and result in brain malfunctioning.
- Tumor: Benign (localised) and malignant (not localised) tumors of the brain in the regions of ventricles, spinal cord and posterior fossa (back inside the skull) can cause CSF blockage.
- Craniosynostosis: A genetic disorder where the sutures (the region where two bones join together) close earlier than expected and this results in a small cranial cavity. This small skull cavity has difficulty in accommodating the extra CSF which again increases the intracranial pressure.
- Meningitis: It is the inflammation of the coverings of brain (dura, pia and arachnoid). The scarring and inflammation because of meningitis inhibits absorption of CSF.
- Arachnoid Cyst: A small fluid (here, the CSF) filled cavity is formed by entrapment in the arachnoid mater as a result of which CSF flow is blocked.
- Spina Bifida: Spina bifida is a congenital defect due to failure of closure of spinal canal and a gap in the vertebrae. The meninges which form a protective covering around the spinal cord and sometimes spinal cord itself protrude out of the vertebral column. Sometimes they are covered with skin, however sometimes they are left completely exposed.
- Idiopathic Intracranial Hypertension: It is a rare congenital disorder commonly seen in women. The intracranial pressure increases and can lead to blindness.
- Congenital Aqueductal Stenosis: Deformities of nervous system impair the circulation of CSF.
- Dandy-Walker Syndrome: A congenital brain malformation that affects the cerebellum (center of movement).
A proper pre-operative assessment is integral to any surgery so that everything goes smoothly without any complications. A few guidelines are given here to help you navigate through the process.
- Before consulting your neurosurgeon, prepare a list of questions you would like to ask. It can be anything from how the surgery is performed, recovery, precautions, etc. Your neurosurgeon will calmly help you through the process.
- Let your doctor know about the details of any previous diseases you had or are suffering from. History of heart disease, diabetes, malfunctions of the liver and kidneys, respiratory (breathing) disorders, bleeding problems, allergies or any other problems should be disclosed to the doctor. This helps in adjusting your treatment plan accordingly.
- Tell about details of medications you are currently taking. It can be blood thinners (warfarin, clopidogrel), pain-relief medications (Aspirin and other non-steroidal anti-inflammatory and analgesic drugs), anti-hypertensives, insulin (for diabetes), etc. Your neurosurgeon may ask you to stop taking some of these drugs or continue them before the surgery.
- Details of radiation and chemotherapy should be given if you are suffering from any malignant/primary tumor.
- People who are suffering from spina bifida are more prone to latex allergies.
- If you drink alcohol, try to limit or stop drinking it altogether. You may experience a few symptoms like nausea, restlessness or dizziness because of this. Your doctor can help treat the withdrawal symptoms you are experiencing.
- Smoking causes breathing problems during the procedure.. It is preferable that you stop it 1-2 weeks before surgery. If you face any difficulty with this, let your healthcare professional know. You can be given a nicotine patch if possible.
Once the neurosurgeon decides to perform the surgery, he would ask you undergo a series of tests to evaluate your fitness before the surgery
- Blood Tests: Blood sugar, complete blood count (CBC), bleeding and clotting time (BT, CT), hemoglobin, platelet count and blood grouping is done.
- Urinalysis: Physical evaluation involves checking color and specific gravity. Presence of blood, sugar and protein is checked. Amount of creatinine is calculated.
- Electrocardiogram (ECG): The electrical activity of heart is measured by placing chest leads and measuring values on a graph paper.
- Chest X-ray: Taken to note any abnormalities of the thoracic cavity.
- Spirometry: To study lung function.
- Renal Function Tests: Blood Urea Nitrogen (BUN) and creatinine levels are calculated.
- Liver Function Tests : Aspartate transaminase (AST) and alanine transaminases (ALT) are two enzymes whose activity is studied to check activity of the hepatic system.
- Electrolytes: Serum electrolyte levels
- Fluid Levels: To avoid a state of hypovolemia (low blood volume) during surgery.
- Examination: Clinical examination is repeated.
- Skin Test: To rule out any allergies.
- Airway examination:to determine suitability for intubation.
- A thorough evaluation should also be done of the region where the excess CSF is going to be drained. For example, if the shunt ends in the lungs, it should be made sure that they are free of any disease, pleural effusions, bronchitis etc.
Your neurosurgeon will like to run a few tests to check the extent of your condition
- CT Scan: Also known as computed tomography scan, it uses radiation to generate 3-D scans of the brain in sliced sections. This gives us an idea about the size, location and extent of brain tumors. It is the preferred diagnostic test to look for any skull fractures.
- MRI Scan: It uses magnetic waves to create images. It is effective for studying soft-tissues in great detail. It can show the buildup of fluid in the brain and any other structural abnormalities present.
- Ultrasound: Ultrasonography uses high frequency sound waves to produce an image of the required region. It is useful in imaging hydrocephalus in its early stages, especially before the birth of the child. It can be placed on the fontanelle (the space at the point where bones close) of a child and cranial structures be studied as needed.
- Lumbar Puncture and Drain: A lumbar puncture can detect the presence of infections such as meningitis and certain cancers. A lumbar drain is done when lumbar puncture cannot improve the symptoms. It is done by inserting a small tube in the lower back to drain out extra fluid. It is carried out under local anesthesia.
- Lumbar Infusion Test: Here fluid is slowly injected into the lower back and pressure is measured simultaneously. Under normal conditions, the body is able to absorb the extra fluid and maintain normal pressure. But in cases of normal pressure hydrocephalus (NPH), the pressure increases; indicating need for surgery.
- Blood Cultures: To study bacterial growth in meningitis.
- Neurological Exam: It is mandatorily done whenever disorders of nervous system are suspected. It includes Glasgow Coma Scale (GCS) to study the eye, muscular and verbal responses along with evaluation of mental status, control and coordination of the body.
Day Before Surgery
- Your appointment will be confirmed by the hospital/surgical centre before the day of surgery.
- Do remember to arrange for conveyance to drop and pick you up from the surgical centre.
- Come accompanied with a dear one who will stay with you throughout the surgery.
- You can take a bath and shower your hair before the surgery, but avoid using any hair products like hairspray or gel.
- Have a good night's sleep. It will help you relax.
- Pack some loose, comfortable clothing preferably with a front opening. Bring along your slippers.
- Carry some things which can keep you distracted during recovery time. It can be books, your I-Pod, or toys if a child is scheduled for the surgery.
- Try not to eat or drink anything in the night before surgery. Solid foods are a strict no-no. You can have clear fluids like broths and soups but strictly nothing 2-3 hours before the procedure.
- Keep your valuables at home.
- Don't apply any lotions, moisturisers or nail polish. Perfumes and deodorants are best avoided.
- You should try to reach the surgical center well on time. Bring your reports along with you.
- The nursing staff will ask you to fill up a few forms and check your vitals (BP, pulse, other blood tests, etc.)
- Your neurologist will come and discuss the procedure with you. If you have any doubts, feel free to clarify them.
- The anesthesiologist will meet you next and tell you about the safety precautions that will be maintained throughout the entire procedure.
- After this, you will be given a consent form. It outlines the entire procedure with its risks and complications. Read them carefully. Only if you feel you are ready to go ahead with the procedure, sign it.
- A portion of your head will be shaved and washed by the nursing staff in order to prevent any chance of infection.
- A clean surgical gown is given to you to be worn for the surgery. Wear it and remove all your jewellery, ornaments, watch and contact lenses (if any).
- An I/V line is attached to your vein in the arm through which medication will be given. You will start feeling drowsy after this.
- Now you will be taken to the operation theater where all the instruments are well sterelised for a safe procedure.
CSF shunt surgery is usually preformed under general anesthesia. It can be administered either intravenously (I/V) or be given via inhalation. A sedative drug is combined with the anesthetic agent to prolong its effect. Now that all your muscles will be relaxed due to anesthesia, a face mask along with a tube is inserted into your airway to help you in breathing.
Your vitals will be maintained and monitored throughout the procedure with the help of pulse oximetry, electrocardiogram, non-invasive blood-pressure, oxygen concentration, and capnography.
Thiopentone and propofol are the choice of anesthetics when inducting whereas sevoflurane or halothane are used if inhalational anesthetic is the chosen method.ketamine should be avoided because it has the potential to increase intracranial pressure. A neuromuscular blocking (NMB) agent is also given to relax the muscles. Neostigmine is used after the surgery to help reverse the effects of NMB agent.
Methods/Techniques of CSF Shunt Surgery
Most of the CSF shunt surgeries follow a standard procedure. The only difference lies in the end-point of catheter insertion. Here is a list of routine shunt procedures that are used
This the most commonly used technique for the treatment of hydrocephalus. Here the shunt catheter goes from the brain ventricle to the abdominal cavity.
A small hole is drilled into the scalp and the meninges removed in that region. The proximal (near) end of the catheter is placed in the enlarged ventricle. Now a valve is attached to this end and placed between the skull and scalp.
The distal (far) end of the catheter will be passed under the skin of the neck, chest and abdomen to drain the fluid into the abdominal cavity. An anti-siphon device is used to control any disturbances in drainage of CSF. The fluid will now enter the abdominal cavity and re-enter blood circulation.
Shunt catheter will emerge from ventricle to insert in the right atrium of the heart. The technique used is similar to that of a VP shunt.
Here the catheter and valve are placed in the jugular vein which collects blood and drains it into the right atrium of the heart.
The shunt catheter will go from ventricles to end in the space outside the lungs (pleura). One end of the catheter is attached in the ventricles and the connection in the lung space is made by making an incision along the ribs, exposing the tissues underneath and placing the distal end of the catheter inside. The incision is then closed in layers. An anti-siphon device is used to prevent over-drainage whenever you sit up straight.
Ventriculo-Cisternal Shunt (Torkildsen procedure)
A shorter shunt, where origin is in the ventricles and termination in the cisterna magna (an opening in the subarachnoid space). This approach is used when there is a block between the ventricles and the subarachnoid space around the brain.
A hole is drilled in parietal bone of skull, the dura (a covering) is removed from that region and one end of catheter is inserted in that region. The other end of the catheter is taken and inserted via the occipital bone so that it meets at the junction of brainstem and spinal cord.
A temporary shunt to divert CSF flow in preterm infants suffering from hydrocephalus. It diverts CSF from the ventricles to subgaleal space (between the scalp and the skull). An incision is made in the skull and catheter is inserted into the ventricle. A low pressure valve placed under the scalp is connected to the catheter and incision is closed. This valve will slowly drain CSF
It is a type of extracranial shunt used to divert excess CSF from the spinal area to the abdominal cavity.
The proximal end of the catheter is inserted into the spine using a needle. The remaining catheter will be channeled through the skin beneath the abdomen.
The technical success of any shunt is dependent on the efficient functioning of its valves. Here we will take a look into how these controllers of fluid dynamics work.
- The valves used in CSF shunt surgeries are usually made of silicone rubber.
- The valves to be used are dependent on the age of patient, amount of pressure to be regulated and the ventricle size.
- Some shunt tubing and valves are coated with antibiotics to reduce the risk of infection during and after the surgery.
- Fixed-Pressure Shunt: Valves in these shunts are adjusted at either low or high pressure which drain the CSF at a set rate.
- Programmable Shunt: These shunts contain special valves that can be adjusted to manipulate the drain rate.
- Magnetic Externally Adjustable Shunt Valves: Magnetic waves are used to adjust the valve settings non-invasively.
- Non-magnetic Externally Adjustable Shunt Valves: As the name suggests, magnetic waves cannot be used to adjust their settings. It is either self regulated or adjustable using minimally-invasive surgical procedure.
Immediately after the surgery, you will be taken to a post-anesthesia care unit (PACU) or post-anesthesia recovery unit (PARU). Your recovery time is dependent on the type of shunt used and the reason for which it was used.
Some machines will be attached to your body that will be measuring vitals. It is normal to feel somewhat tired after surgery. Once you are awake and the anesthesia has worn off, you will be shifted to the hospital ward.
- The nursing staff will take care of you and assess your neurological condition for a few days by asking you some questions everyday.
- Your incisions will be covered with dressings which will be removed by the neurosurgeon 1-2 days after surgery.
- A review CT scan is taken after 2 days to check the position of the catheter placed in the brain.
- Normally it takes about 3-4 days to recover from a CSF shunt surgery. After being satisfied with your fitness levels, your doctor will discharge you from the hospital after 7 days.
- Take plenty of rest at home for the first 1-3 weeks.
- Start with walking first inside your home then outdoors.
- Try not to bend too much to pick up things.
- Avoid lifting heavy objects or doing any strenuous activity.
- You can start running after 2 weeks.
- You can resume driving only on the advice of your doctor.
There are no particular restrictions on your diet after surgery. You can have what you used to have before. Take care to supplement your diet with nutritious food to encourage proper wound healing.
- Your neurosurgeon will prescribe a list of medications to be taken after surgery. Take them exactly as per instructions.
- Ask your doctor when you can start taking your previous medications.
- Don't start taking pain-killers and blood thinners on your own.
- It is common to experience headache for a few days after surgery. You will be prescribed appropriate pain-killers for that. Pain-killers tend to irritate your stomach lining so it is advisable to take some antacid along with that.
- Constipation is a side-effect of narcotic pain-killers. If your bowel movements bother you, take a laxative to smoothen them out.
- You can start taking showers after surgery but no tub baths, whirlpools or swimming pools.
- Try not to apply any lotions or creams near the incision site.
- Always keep the incisions clean and dry.
- Avoid putting your head underwater.
- Your staples on the incision will probably still be in place even after you are discharged.
- Try keeping your incisions dry by keeping them open to the air.
- Always cover your incisions with plastic wrap before showering.
- In the initial days, ask someone to help you with bathing. If in contact with water, wash your incision, but don't scrub it.
The standard recovery time from a CSF shunt surgery is about 2.5-3 months.
If you find or experience any of the following signs and symptoms, do not waste any time in contacting your doctor
- Unexplained fever
- The area around the incision swells.
- You experience something different about your consciousness.
- Diplopia (double vision)
- Nausea and vomiting
- Seizure (fits)
Your neurologist will let you know about the follow up schedule after surgery. Initially it will be scheduled 10-21 days after surgery and the frequency of future appointments can be tapered down gradually. Children are closely monitored to see if there is any need for a revision surgery.
Risks And Complications
The risks associated with CSF shunts are outlined as follows
- Reaction to Anesthesia: This includes nausea, vomiting, headache, dizziness, respiratory depression, coma etc.
- Infection: As with any foreign implanted body, shunts pose a risk of infection as well. The bacteria stick to the shunt and start growing. Symptoms can start with low grade fever, redness and tenderness along the shunt area and soreness along the neck muscles.
- Blockage: A blockage in the shunt can be because of entrapment of tissues, bacteria or blood cells in the system. If the blockage is not resolved, the symptoms of hydrocephalus can return. But this problem can be corrected with the help of surgery.
- Drainage Problems:
A shunt can present with two types of drainage issues:
- Under Drainage: The CSF drains slowly from the ventricles of the brain as compared to the expected rate of drainage. Because of this, it starts pooling in the brain and can bring back symptoms of the pre-existing disease (hydrocephalus).
- Over Drainage: Occurs in 5-10% of the cases. Here the CSF shunt drains the fluid from the brain ventricles a lot quicker than expected. As a result, the ventricles can collapse and tear the blood vessels causing severe bleeding, headaches, nausea, vomiting and seizure like symptoms.
- Calcification: The shunt catheter can calcify and break.
- Length Discrepancy: Length of the shunt may be too long or too short.
- Valve Failure: Shunt valves may break or set to the wrong pressure.
- Subdural Hematoma: It is collection of blood outside the brain. They are seen in cases when the patient may have a fall or even get a tiny bump on the head after the shunt surgery Acute subdural hematomas tend to get expanded in the presence of CSF shunts.
- Slit-ventricle Syndrome: It is named so because of the typical slit like appearance of the brain ventricles in the CT scan or MRI. It is seen in patients after some years who have the ventriculoperitoneal shunts placed in them. The increased intracranial pressure from other ventricles or in instances where the shunts are blocked may compress the barely working ventricle.
- Intraventricular Hemorrhage: Uncontrolled bleeding can occur at any time during or after a shunt insertion. The hemorrhage can cause a disruption in the shunt function and result in several neurological problems.
- Will my condition worsen after a shunt is placed in my brain?
A. Ideally, it shouldn't. If your shunt is working well, your condition will remain under control and not cause you any problem. However, a shunt cannot control age-related changes in the brain.
- My child has a CSF shunt. Will he need another one again?
A. Yes. Shunts are placed in the brain according to the current growth status of the patient. With growing age, the physical status of the body changes. A revision surgery may be required according to the needs of the child.