Introduction
The term retro-sigmoid describes the portion of the skull behind the ear. A craniotomy is a surgery to visualize the brain by removing a part of the skull bone and providing better access. The procedure gives a broad exposure and enough working area for lesions at the retrosigmoid region. The bone removal is minimal compared to other craniotomy approaches and is an efficient way to access the tumors behind the skull. Thorough knowledge of the process and the skilled hands of an experienced surgeon help to bring a successful outcome.
What Is Retrosigmoid Craniotomy?
A craniotomy is a temporary procedure to remove a part of the skull and expose the brain to treat various intracranial pathologies. There are many different approaches available to perform a craniotomy. One such method is the retrosigmoid or the keyhole craniotomy to treat skull base tumors through an opening created behind the ear. It is a minimally invasive technique that has a rapid recovery time.
Who Requires a Retrosigmoid Craniotomy?
A retrosigmoid craniotomy approach is helpful in the following conditions:
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In tumors like Schwannoma (a tumor of the nerve sheath or the layer protecting the nerve), meningioma (a tumor of the membrane that surrounds the brain and spinal cord- the meninges), and ependymoma (tumor involving the brain and the spinal cord).
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In non-cancerous conditions such as epidermoid cyst (present below the skin), arachnoid cyst (brain cyst), and papilloma (an outward overgrowth).
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In vascular lesions such as cavernomas (clusters of abnormal blood vessels at the brain and the spinal cord), aneurysms (abnormal ballooning of the blood vessel wall), and arteriovenous malformation (abnormal tangling of blood vessels between the arteries and the veins).
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In placing midbrain implants (a hearing prosthesis).
It is generally used to treat pathologies at the cerebellopontine angle (a triangular space between the cerebellum and pons portion of the brain), internal auditory meatus (in the back of the skull behind the ear) and other areas in the base of the skull.
What Are the Advantages of the Retrosigmoid Craniotomy?
The benefits of retrosigmoid craniotomy surgery include:
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The surgery involves smaller incisions and minimal bone removal.
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Less exposure to the surrounding normal structures of the brain.
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The postoperative pain after the surgery is less, and increased consumption of painkillers is not required.
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The patient will have a faster recovery after the surgery, and the patient can resume everyday activities in a few days.
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The patient can discharge within one or two days from the hospital.
How to Prepare a Patient for Retrosigmoid Craniotomy Surgery?
Before the surgery, the patient must undergo a few medical tests, and complete medical history is noted.
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The doctor will discuss the surgical procedure, and the patient signs a consent form as a willingness to start the procedure.
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If the patient is an active smoker, the habit must be quit at least two weeks before the surgery for proper healing.
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If the patient is under any medication, such as a blood thinner (Aspirin), it is stopped for a few days with the physician’s consent. Medicines such as vitamin E are also stopped two weeks before the surgery.
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The doctor prescribes medications that the patient has to consume before the procedure.
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Any allergy to the medication or anesthesia is noted to prevent complications after the surgery.
How to Perform Retrosigmoid Craniotomy Surgery?
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The procedure is done under general anesthesia to make the patient unconscious and painless during the operation.
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The patient is placed in a position with the body facing upward, and the head is turned towards the opposite side.
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The location of the operation is identified, and an antiseptic solution is applied to keep the area sterile.
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An incision five centimeters long is carefully made from behind the ear without damaging the underlying nerves and blood vessels.
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A high-speed drill makes holes in the bone of approximately 2 to 2.5 centimeters.
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After removing a small portion of the bone, the dural layer covering the brain is cut and elevated to access the structures within the brain.
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The surgeon can now operate in this region and remove the lesions or tumors with ease.
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Finally, the elevated dural layer has to be closed in a watertight manner using sutures.
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The bone removed to expose the brain is reconstructed using bone grafts obtained from the same individual.
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Above the bone graft, a titanium plate is placed to provide additional support to it.
The surgeon also combines the retrosigmoid approach with an endoscope (an instrument with a camera at one end to visualize the inner structures in detail from the outside) for a wider visual field and to see the surgical site clearly. It can also be performed microsurgically. Sometimes, the smaller lesions in the skull base can be removed using an endoscopic approach alone.
What Are the Complications Associated With Retrosigmoid Surgery?
Any surgery on the body involves numerous risks and complications. It is up to the doctor and the patient to decide how to overcome these complications. The following are the risks involved in the surgery.
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General complications like allergic reactions to anesthesia, bleeding, pain, and blood clot formation.
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One of the major complications is cerebrospinal fluid leakage. The cerebrospinal fluid acts as a shock absorber and is present in the subarachnoid space around the brain. The leakage must be prevented, or it leads to additional surgical procedures.
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Persistent headache at the operation site.
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Infection at the incision site.
The surgeon must be ready to deal with the complications and manage them immediately to prevent any unfavorable outcomes after the surgery.
What Are the Postoperative Instructions to Be Followed After Retrosigmoid Surgery?
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The patient must consume the painkillers prescribed by the surgeon regularly.
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The sutures placed at the operation site should not be disturbed. The surgeon will remove the sutures after one week during the follow-up appointment.
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Avoid lifting heavy objects or exercises that strain the body for at least four weeks after the surgery.
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After a few days, the patient can resume normal activities gradually with the physician’s consent.
Any changes like bleeding, swelling, pain, or discomfort the patient notices must be reported to the doctor immediately to review the condition and manage any complications. The patient has to visit the doctor on the scheduled dates to check on the progress of the condition.
Conclusion
The retrosigmoid craniotomy is a safe and effective approach to treating the lesions at the base of the skull behind the ear. A highly skilled surgeon with expertise in the technique can perform the procedure without causing complications. The healing is faster compared to other approaches used in craniotomy, and the success rate of treating the lesions through this approach is also good.
