Project Description

The concept of Minimally Invasive Neurosurgery introduces highly refined techniques and approaches, to the neurosurgical treatment of brain and spinal diseases.

Major advances in neurological surgery have occurred over the past 30 years’ consequent to the development of microneurosurgical instrumentation and procedures, the improvement and reliability of diagnostic neuroimaging methods (MRI and CT scanning), and the availability of sophisticated anaesthetic techniques.

Currently we are enjoying the “next step” in the evolution of neurosurgical capabilities with the introduction of Minimally Invasive Neurosurgery techniques. While the operations still require the “opening” of the skull for brain operations, these openings for exposure are much smaller than ever previously contemplated. Another method of brain minimally invasive surgery is endoscopic surgery through the patient nose which is applicable for Craniopharyngioma surgery and pituitary adenoma.

Craniopharyngioma Surgery

Craniopharyngioma

Craniopharyngiomas are dysontogenic tumors with benign histology and malignant behavior. These lesions have a tendency to invade surrounding structures and to recur after a seemingly total resection (see the image below).

Craniopharyngiomas most frequently arise in the pituitary stalk and project into the hypothalamus. They extend horizontally along the path of least resistance in various directions, as follows:

  • Anteriorly – Into the prechiasmatic cistern and subfrontal spaces.
  • Posteriorly – Into the prepontine and interpeduncular cisterns, cerebellopontine angle, third ventricle, posterior fossa, and foramen magnum.
  • Posteriorly – Into the prepontine and interpeduncular cisterns, cerebellopontine angle, third ventricle, posterior fossa, and foramen magnum.

Clinical behavior and the choice of surgical approach are dictated by the primary location of the tumor and its extension pattern. Prechiasmatic craniopharyngiomas (extending into sub frontal spaces) and retrochiasmatic craniopharyngiomas (expanding into the posterior fossa) may become large before being diagnosed.

Craniopharyngioma usually presents as a single large cyst or multiple cysts filled with a turbid, proteinaceous, brownish yellow material that glitters owing to the high content of floating cholesterol crystals.

Craniopharyngioma causes symptoms in the following ways:

  • Increasing the pressure on the brain (intracranial pressure)
  • Disrupting the function of the pituitary gland
  • Damaging the optic nerve

Increased pressure on the brain causes headache, nausea, vomiting (especially in the morning), and difficulty with balance. Damage to the pituitary gland causes hormone imbalances that can lead to excessive thirst, excessive urination, and stunted growth. When the optic nerve is damaged by the tumor, vision problems develop. These defects are often permanent, and may get worse after surgery to remove the tumor.Behaviorial and learning problems may be present.

Most patients have at least some vision problems and evidence of decreased hormone production at the time of diagnosis.

Essentially, 2 main management options are available for craniopharyngiomas: (1) attempt at gross total resection or (2) planned limited surgery followed by radiotherapy.

No firm consensus of opinion exists concerning the appropriate management of craniopharyngiomas, and no guidelines have as yet been established.

Gross Total Resection

Gross total surgical removal has traditionally been the treatment of choice for craniopharyngiomas. The surgical approaches for resection include the standard pterional approach; the orbitocranial approaches; and the sub frontal, transsphenoidal, and transcallosal approaches. A combination of approaches may occasionally be necessary. Tumor adhesion to surrounding vascular structures represents the most common cause of incomplete tumor removal.

If the pituitary Sella is not enlarged, the trans sphenoidal approach is generally not preferred. A craniotomy is usually necessary when the predominant component is suprasellar, although certain suprasellar masses may be located through an extended trans sphenoidal approach. New technology in optics and instrumentation has now permitted many trans sphenoidal procedures to be done exclusively through the endoscope.

The pterional craniotomy is the standard craniotomy approach to suprasellar lesions because it allows good visualization of the optic nerves, chiasm, and surrounding structures.

A sub frontal approach is appropriate for lesions that lie anterior to the optic chiasm, but this may be difficult to determine preoperatively. Under rare circumstances, a transcallosal approach is necessary when the tumor is entirely within the third ventricle. The drawback to this approach is the inability to identify the optic chiasm and pituitary stalk early in the dissection.

Limited Surgery and Radiotherapy

Recent studies propose subtotal resection with postoperative radiotherapy as the management paradigm of choice for craniopharyngiomas. Goals of this approach include pathologic confirmation of the tumor and surgical decompression of the optic chiasma. Surgery is followed by external beam radiation.

Complete surgical removal of craniopharyngiomas can be achieved with reasonable safety in the majority of patients. Aggressive attempts at total tumor removal may lead to increased rates of anterior hypopituitarism, diabetes insipidus, growth disturbances, and behavioral and feeding abnormalities. On the other hand, subtotal resection with adjuvant radiotherapy can provide tumor control rates essentially similar to those for gross total resection while limiting hypothalamic and hypophyseal morbidity.

Recurrence

Craniopharyngiomas have a high propensity for recurrence, mostly in the first 3 years after surgery. Overall recurrence rates range from 0-17% after gross total resection and from 25-63% after subtotal resection with radiotherapy. However, 2 studies have reported recurrence rates of 53-62% even after apparent complete removal of the tumor. One series assessed only pediatric patients and the other included patients younger than 25 years. Therefore, young age may be a risk factor for tumor recurrence independently of the degree of tumor excision. Ultimately, if left untreated, these recurrences may cause death through aggressive local behavior.

Moreover, to compare more brightly, the incidence of tumor progression after subtotal surgical resection and radiotherapy ranges from 12-25% and is similar to rates associated with failed gross total resection and radiotherapy (4-25%).

Skull Base Tumors

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