The Suprasellar region as the name implies is located above the Sella turcica (syn. Turkish saddle), a depression in the base of the skull which houses the Pituitary gland. It consists of four cisterns which contain critical neurovascular structures including the Suprachiasmatic, Subchiasmatic cisterns (located in relation to the Optic chiasm of the visual apparatus), Retrosellar cistern (located behind the sella turcica) and the Third ventricle.
The Chiasmatic cistern (shown in the picture above) is bound by the diaphragma sellae ( a diaphragm above the sella turcica marked by arrowheads 4) below and the optic chiasm above; with Internal Carotid Arteries on both sides (Marked by arrowhead 3). The pituitary stalk (arrowhead 1) is the epicenter of this cistern.
Behind the Pituitary stalk lies the Interpeduncular cistern. The oculomotor nerves (III) form its lateral boundaries. The Basilar Artery (BA) pierces the Lilliequist membrane from the prepontine cistern to enter this cistern. Legends: PCA (P1)- P1 segment of right Posterior Cerebral Artery, SCA- Superior Cerebellar Artery, MB- Mammillary body, pons,- ventral surface of pons.
The picture below uses a Xray Skull lateral view to depict the Sellar- Suprasellar region. Tumors in the region may be purely Suprasellar or Sellar with extension into the Suprasellar cisterns.
The prototype tumor that occurs in the Suprasellar region is the Craniopharyngioma. Craniopharyngiomas account for up to 15% of the intracranial tumors in children with peak incidence rates at the age of 5–14 years. Almost 80% of these have are large cystic tumors. A second peak occurs in adults around 60 years of age. This tumor of the hypothalamo-pituitary region develops from embryonic remnants of Rathke’s pouch and sac.
Though benign in appearance the clinical behavior of Craniopharyngioma is aggressive, causing serious morbidity by damaging the optic chiasm, the pituitary, and hypothalamic area. The severity of symptoms and signs is directly related to the tumor’s size, position, and exact location. Disturbance of cerebrospinal fluid (CSF) flow often causes Obstructive hydrocephalus.
The early symptoms often are non-specific manifestations of increased intracranial pressure such as headache and nausea are often missed. Almost three-quarters of children have severe visual impairment and endocrine deficits manifesting as growth impediment and Diabetes insipidus. Older children may present with premature puberty and/or unmanageable weight gain. Adults often present with raised intracranial tension, visual impairment and endocrine deficits.
Chiasmal gliomas: These are low grade gliomas called Pilocytic astrocytomas which arise from the visual apparatus in the first two decades of life affecting vision. Hypothalamic disturbances are common due to its proximity. A large tumor can produce hydrocephalus.
This large Chiasmal glioma in a 5 year old boy presenting with growth retardation, developmental delay, visual deterioration and raised intracranial symptoms was operated by a Right Frontal craniotomy and subfrontal approach. The pink tumor is seen (white arrowhead) and the right Olfactory nerve which is the anatomical landmark guiding the surgeon to the tumor is shown by the white arrow.
Hypothalamic gliomas and hamartomas: These discrete lesions often present with hypopituitarism. Other manifestations seen in early childhood include Precocious puberty, Diencephalic syndrome, Diabetes insipidus, Syndrome of Inappropriate ADH secretion (SIADH). Hamartomas present with an unusual form of epilepsy called Gelastic seizures and developmental delay though Precocious puberty is the classical presentation.
Magnetic Resonance Imaging MRT1W in midsagittal plane shows a low grade Hypothalamic glioma.
Two rare tumor in the Suprasellar region seen in children are Germinoma and Langerhans cell histiocytosis. Diabetes insipidus is seen early in presentation along with raised Intracranial Tension due to hydrocephalus. A simultaneous posterior third ventricular tumor component in Germinomas may be present resulting in Parinaud’s syndrome (Inability to look upwards).
High resolution MRI using thin sections (2 or 3 mm) coronal and sagittal T1-weighted images through the pituitary-hypothalamic axis before and after intravenous administration of gadolinium are the main-stay of neuroimaging. The calcification and hemorrhage in the tumor is best appreciated on computed tomography (CT) scan.
On the basis of imaging results and clinical symptoms differential diagnosis between the various tumor entities should be feasible in most cases. Of course, only in strictly defined cases like typical chiasmatic/hypothalamic and optic pathway gliomas or germinomas a histological confirmation is dispensable.
All other cases require a biopsy using a Craniotomy and Subfrontal approach. Occasionally a transsphenoidal approach may be feasible. The issue of hydrocephalus, if present may mandate a diversionary shunt surgery. Craniopharyngiomas may be treated with limited resection followed by Radiotherapy.
Suprasellar tmours in childhood are best considered as chronic diseases which are best managed by a team combining the efforts of Pediatricians, Neurosurgeons, Endocrinologists and Radiotherapists.
Hypothalamic involvement and/or treatment-related injuries to the optic pathway and critical brain structures result in impaired physical and social functionality and severe neuroendocrine sequel.