Brain Tumors – Keyhole, Endoscopic and Minimally Invasive Surgery

Brain Tumors – Keyhole, Endoscopic and Minimally Invasive Surgery

What is a brain tumor?

A brain tumor is a growth of abnormal cells in the brain. Brain tumors can develop in any part of the brain or skull, including its protective lining, the underside of the brain (skull base), the brainstem, the sinuses and the nasal cavity, and many other areas.

Are Brain tumors dangerous?

Yes, Braintumors are dangerous because they can put pressure on healthy parts of the brain or spread into those areas. Some brain tumors can also be cancerous or become cancerous. They can cause problems if they block the flow of fluid around the brain, which can lead to an increase in pressure inside the skull. Some types of tumors can spread through the spinal fluid to distant areas of the brain or the spine.

How is a tumor different from a brain lesion?

A brain tumor is a specific type of brain lesion that consists of growth of abnormal cells. A lesion describes any area of damaged tissue. All tumors are lesions, but not all lesions are tumors. Other brain lesions can be caused by stroke, injury, encephalitis and arteriovenous malformation.

Benign vs. Malignant?

Benign brain tumors grow slowly, have distinct borders and rarely spread. They can damage and compress parts of the brain, causing severe dysfunction. Benign brain tumors located in a vital area of the brain can be life-threatening. Very rarely, a benign tumor can become malignant. Malignant brain tumors are cancerous. They typically grow rapidly and invade surrounding healthy brain structures. Brain cancer can be life-threatening due to the changes it causes to the vital structures of the brain.

Primary vs Metastatic Brain Tumors?

Primary brain tumors start in the brain. Examples of tumors that most often originate in the brain include meningioma and glioma. Very rarely, these tumors can break away and spread to other parts of the brain and spinal cord. Metastatic brain tumors, also called secondary brain tumors, are malignant tumors that originate as cancer elsewhere in the body and then spread to the brain. Metastatic brain tumors are more common than primary brain tumors.

Brain Tumor Symptoms

The tumor’s size and how fast it’s growing also affect which symptoms a person will experience. Different parts of the brain control different functions, so brain tumor symptoms will vary depending on the tumor’s location. For example, a brain tumor located in the cerebellum may cause trouble with movement, walking, balance and coordination. If the tumor affects the optic pathway, which is responsible for sight, vision changes may occur.

Should brain tumors always cause symptoms?

Brain tumors don’t always cause symptoms. In fact, the most common brain tumor in adults, meningioma, often grows so slowly that it goes unnoticed. Tumors may not start causing symptoms until they become large enough to interfere with healthy tissues inside the brain and that makes early detection and diagnosis of these lesions very difficult.

What is keyhole surgery for brain tumors?

Keyhole surgery is the concept of safely removing brain & skull base tumors through smaller, more precise craniotomies that minimize collateral damage to the surrounding brain, blood vessels, and nerves and improve patient outcomes. This needs improved understanding of intracranial anatomy and different technology and instrumentation with skilled neurosurgeons who are trained in these approaches. Eventhough the spectrum of conditions that can be handled with these approaches increase by the day, not all conditions can be dealt with these approaches.

The ideal surgical approach for each patient is determined by the specific tumor type and location. Regardless of the route chosen, our goals are to maximize tumor removal and minimize manipulation of critical structures. Thereby avoiding complications and patient disfigurement, while promoting a more rapid, complete and less painful recovery.

Keyhole and Minimally invasive approaches

Supraorbital Eyebrow Craniotomy

This versatile, minimally invasive approach minimizes normal tissue disruption and brain retraction, allowing for a more direct approach to lesions. This approach is typically performed with the assistance of an endoscope, allowing for further visualization. As such, patients recover well and have good cosmetic outcomes long term.

Endoscopicendonasal surgery

Endoscopic Endonasal Surgery (through the nostrils) is ideal for most pituitary adenomas, craniopharyngiomas, chordomas, sinus carcinomas, olfactory neuroblastomas and some midline meningiomas of the tuberculumsellae, clivus, cavernous sinus, Meckel’s cave, orbital apex and orbit.

Mini-Pterional Approach

The Mini-Pterional Approach is used for certain sphenoid wing and parasellarmeningiomas, aneurysms, other tumors of the cavernous sinus and Meckel’s cave, orbital lesions as well as temporal lobe gliomas. Patients recover relatively quickly in comparison with traditional pterional operations, with potentially less pain, chewing difficulties and facial muscle atrophy.

Gravity-Assisted Brain Tumor Surgery Approaches

By using gravity to allow for the normal brain to fall away, there is no need for fixed brain retraction and there is minimal normal brain traversed to reach these midline, deep lesions. (A) Gravity Assisted Trans-Falcine Approach, (B) Gravity assisted Trans-Tentorial Approach.

Endoscopic Trans-Ventricular Route

For tumors and cysts within the ventricles: colloid cyts, gliomas, metastatic brain tumors and pineal tumors.

Tubular retractor/Brain Port Approach

MIOT neurosurgeons can navigate between the natural folds and neural structures in the brain, to minimize collateral damage to the surrounding brain along the path to reach the tumor or blood clot.

Awake Brain Surgery

Awake brain surgery, also called awake craniotomy, is a type of procedure performed on the brain while you are awake and alert. Awake brain surgery is used to treat some brain (neurological) conditions, including some brain tumors when the tumors are very near areas which control movement,vision or speech. This is mainly done to preserve these functions and to improve patient outcomes after surgery.It also helps neurosurgeons to maximise tumor resection without the fear causing deficits in their patients.

For whom it is ideal?

A cooperative and motivated patient is the most important part of a successful awake craniotomy. Before surgery, your neurosurgeon or a speech-language pathologist may ask you to identify pictures and words on cards or on a computer so that your answers can be compared during surgery. Tumor and lesional size and characteristics also feature in when the surgeons decide on whether awake procedure is the right choice.

Multidisciplinary team effort is the cornerstone of a successful awake procedure with Neurosurgeons, speech and language pathologist, anesthesiologist playing their parts as a team. Awake craniotomy in done in either sleep-awake-sleep method or sleep-awake-awake method. Patient will be woken after the craniotomy is done with anesthesia with the pain taken care by the anesthesiologist. Baseline assessment of motor and language functions done and the surgery is proceeded with excision of the lesion with constant monitoring of the functions. After maximal resection with preserved functions, patient is again put to sleep to complete the procedure.

This is the fool-proof gold standard when it comes to the preservation of functions when compared to any other method. What can prove the preserved functions in a patient undergoing surgery under anesthesia than awakening the patient and checking the functions ourselves?

At MIOT, with the help of the multidisciplinary team available, we have performed many successful awake craniotomies leading to better functional outcomes in patients alongside maximising the extent of tumor resection.

INTRA-OPERATIVE NEUROMONITORING

Intraoperative neurophysiological monitoring (IONM) helps assess the integrity of neural structures and consciousness during surgical procedures. It includes both continuous monitoring of neural tissue as well as the localization of vital neural structures. The goal of IONM is to identify intraoperative neural insults that allow early intervention to eliminate or to significantly minimize irreversible damage to the neurological structure and prevent a postoperative neurologic deficit. The use of neurophysiological monitoring during surgical procedures requires specific anesthesia techniques to avoid interference and signal alteration due to anesthesia.

Different modalities of intraoperative neurophysiological monitoring (IONM) are:

INDICATIONS:

Intraoperative neurophysiologic monitoring (IONM) is recommended for individuals at increased risk of neurological injury during surgical procedures. The following are the indications for IONM.

Somatosensory Evoked Potential (SSEP) or Motor Evoked Potential (MEP)

Spine and spinal cord surgery including scoliosis and Kyphosis correction with instrumentation, spinal cord decompression/stabilization, anterior and posterior spinal fusions (cervical, thoracic, and thoracolumbar), the release of tethered cord, correction of spina bifida, resection of the tumor, cyst, aneurysm or arteriovenous malformation of the spinal cord

Brain and brain stem surgeries including craniotomy for tumor removal, craniotomy for aneurysm repair, arteriovenous malformation repair, localization of cortex during craniotomy, thalamotomy Cerebrovascular surgery, including clipping of intracranial aneurysms, interventional neuroradiology Brachial plexus and lumbosacral plexus surgery Peripheral nerve repair Carotid endarterectomy

Electromyography (EMG)

To monitor cranial nerve function during procedures including acoustic neuroma resection, microvascular decompression of the facial nerve, parotid tumor resection, vestibular neurectomy for Meniere disease, neurotologic/otologic procedures. Nerve root or spinal cord monitoring during spinal surgeries including spinal instrumentation (e.g., pedicle screw placement), a mechanical spinal distraction Resection of skull base tumors, spinal tumors. Surgical excision of cranial nerve neuromas of motor cranial nerve. Brachial or lumbosacral plexus surgery.

Why IONM?

Intraoperative neurophysiological monitoring (IONM) is considered the standard of care during many procedures, including spinal, intracranial, and vascular surgeries, where there is a risk of neurological damage. Effective communication and close cooperation between multidisciplinary teams, including intraoperative neuromonitoring (IONM) technician, a neurophysiologist, anesthesiology, and surgery team, is required for high-quality perioperative care to detect and prevent neurologic injuries.

Various modalities of neurophysiological monitoring are used to monitor neural structures during different types of surgery. IONM team collaborates with the surgical and anaesthesiology team to optimize signal acquisition and provide real-time analysis, interpretation, and timely communication of signal changes, which allows the surgeon to operate safely and avoid neural tissue injury.

At MIOT,most of our brain and spine surgeries are done with intraoperative neuromonitoring guidance towards providing better functional outcomes for our patients.

Brain mapping with Functional MRI and Diffusion tensor imaging

Functional MRI is a noninvasive diagnostic test that measures small changes in blood flow as a person performs tasks. It detects the brain in action (e.g., speaking or moving). It has an advantage over other imaging studies in the way that it focuses on the functional localization while other tests can image only the structures.

Diffusion tensor imaging (DTI) detects the white matter fibers that connect different parts of the brain. These imaging studies help to map specific brain areas before surgery.

How does functional MRI work?

When we start a activity, neurons in our brain responsible for the action use more oxygen and demand more blood. Functional magnetic resonance imaging (fMRI) can detect the difference in signal caused by the increase in blood flow to specific areas of the brain. The MRI scanner measures this signal difference and displays the activity as a colored area.

Diffusion Tensor Imaging (DTI) is a technique that detects how water travels along the white matter tracts in the brain . White-matter tracts connect different parts of the brain and must be protected during surgery(Part of the circuits that are subcortical).

What does a functional MRI show?

Functional MRI gives detailed pictures of brain activity. It is used to determine precisely which part of the brain is handling critical functions such as thought, speech, vision, movement and sensation. It can also show the effects of stroke, trauma or Alzheimer’s on brain function.

These imaging studies are important in planning surgery – called brain mapping – that helps surgeons remove tumors to the greatest extent possible without causing deficits in functions that are critical to a patient’s quality of life. Brain mapping is essential in not only tumour resection surgeries but also in all surgeries where preserving function is essential Example being Epilepsy surgery/Functional disconnection surgeries.

MIOT Neurosurgeons use Pre-op Brain mapping merged into the state of art intra-op navigation that is integrated with intraoperative CT scan for better out come of patients.