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Craniotomy for Meningiomas
Meningioma is the second most common primary intracranial tumour, second only to gliomas, accounting for approximately 15 to 24% of intracranial tumours.
A Benign Tumour That Can Be Completely Cured by Total Resection
The annual incidence of meningioma is about 6 per 100,000 people, and it can occur at any age, particularly in adults aged 30 to 50, with a higher prevalence in females (ratio of 1:2 male to female). Approximately 95% of meningiomas are benign and grow slowly, with an average annual growth rate of 1 to 2 centimetres or 3.6% in volume. Consequently, the tumour often remains asymptomatic for a prolonged period within the patient's brain.
Reports suggest that the average time for early symptoms of meningioma to manifest is 2.5 years, with some cases extending up to 6 years. Due to the slow growth rate, early detection is challenging, and symptoms typically appear when the tumour has already grown significantly. The neurological symptoms of meningioma depend on the tumour's location and the extent of nerve compression. Tumour compression can also cause peritumoral cerebral oedema, leading to increased intracranial pressure. Common symptoms include headache, dizziness, unilateral limb numbness or weakness, gait instability, blurred vision, olfactory or auditory disturbances, personality changes, vomiting, seizures, and neuralgia.
Since meningiomas are benign tumours, complete resection can achieve a cure. If total resection is not feasible, partial resection to decompress the nerves can yield satisfactory outcomes. Partial resection followed by stereotactic radiotherapy can cure most meningiomas. Generally, for meningiomas on the cerebral convexity, neurosurgeons aim for total resection to minimise recurrence risk, provided it is safe and feasible. However, if the tumour is located in a high-risk area (e.g., medial sphenoid wing, orbit, sagittal sinus, ventricles, cerebellopontine angle, optic nerve sheath, or clivus), complete resection may carry the risk of permanent neurological deficits, prompting surgeons to opt for partial resection to decompress the nerves.
Case 1: Benign Skull Base Meningioma
This case involves a 50-year-old female patient from mainland China, who presented with a six-month history of headache and blurred vision. MRI in China revealed a 2 cm tumour at the skull base, extending upwards and compressing the optic nerve, also encasing the bilateral internal carotid arteries (ICA) and anterior cerebral arteries (ACA) (see Figure 1).
A six-hour minimally invasive craniotomy was performed to completely excise the tumour under a microscope, decompressing the optic nerve and preserving the bilateral ICA and ACA intact (see Figure 2). Postoperatively, the patient's vision returned to normal, and she returned to mainland China three days later. MRI scans one year and four years post-surgery confirmed no recurrence of the tumour.
Figure 1
Figure 2
Case 2: Benign Meningioma at the Left Petroclival Region
This patient presented with a 3 cm meningioma causing compression and distortion of the brainstem and cranial nerves V to XII at the skull base (see Figure 3). Symptoms included left-sided facial neuralgia resembling electric shocks. The patient underwent minimally invasive neurosurgery with continuous neurophysiological monitoring. A 12-hour microsurgical resection was performed, completely excising the tumour (see Figure 4).
Due to tumour compression, cranial nerves VII (facial nerve) and VIII (auditory nerve) were severely displaced, causing nerve distortion. During tumour resection, precise manipulation within 1 to 2 cm was necessary, requiring meticulous technique and direction to protect the nerves. The most common surgical risks include permanent hearing loss or temporary to permanent facial nerve paralysis. Medical literature documents cases where surgical risks and complications can lead to severe disability or even death due to brainstem nerve or vascular injury. Fortunately, in this case, all cranial nerves, their functions, microvessels, and the major basilar artery were preserved without damage.
Reflecting on this arduous task, the surgery extended to 12 hours, doubling the initially anticipated 6 hours, necessitating cautious dissection of the tumour from fragile nerves and blood vessels, and separating it from normal brainstem and cerebellar tissues. During surgery, the surgeon's adrenaline levels naturally rise, negating physiological needs (e.g., hunger, fatigue, urination). However, post-surgery, there is significant physical fatigue and pain in the hands and shoulders, but the successful outcome makes it all worthwhile.
Due to the complete tumour removal, planned postoperative stereotactic radiosurgery was deemed unnecessary. Follow-up MRI one month and two years post-surgery showed no tumour recurrence.
Figure 3
Figure 4
The most common symptoms of meningiomas include headache, dizziness, unilateral limb numbness or weakness, gait instability, blurred vision, olfactory or auditory disturbances, personality changes, vomiting, seizures, and neuralgia.