A suprasellar mass is an abnormal growth located in the suprasellar region of the brain. This area sits directly above the sella turcica, a saddle-shaped depression in the sphenoid bone at the base of the skull. Growths in this location can impact various nearby brain structures, leading to a range of symptoms.
Understanding Suprasellar Masses
The suprasellar region, located above the sella turcica, is dense with important structures. These include the optic chiasm, optic nerves, hypothalamus, pituitary stalk, and parts of the Circle of Willis, a network of blood vessels. Growths in this region can exert pressure on these delicate tissues, leading to various neurological and hormonal disturbances.
Pituitary adenomas are benign tumors originating from the pituitary gland that can extend upwards into the suprasellar space, especially if they are macroadenomas (larger than 10 mm). Craniopharyngiomas are another type, arising from embryonic tissue remnants near the pituitary gland, often characterized by calcifications and cystic components. These tumors are slow-growing and can affect both children and adults.
Meningiomas, which are usually benign, develop from the meninges, the protective membranes surrounding the brain and spinal cord. Suprasellar meningiomas tend to affect middle-aged individuals. Other potential suprasellar masses include germ cell tumors, more common in children and young adults, and hypothalamic gliomas, which are tumors of glial cells in the hypothalamus or optic chiasm. Aneurysms, which are balloon-like bulges in blood vessels, and inflammatory lesions like sarcoid granulomas or pituitary abscesses can also occur.
Common Symptoms
Symptoms of a suprasellar mass depend on which adjacent brain structures are affected. Visual disturbances are frequent due to compression of the optic chiasm or optic nerves. This can lead to blurred vision, double vision, or bitemporal hemianopsia, a visual field loss affecting peripheral vision in both eyes. As the mass grows, it can potentially lead to complete vision loss in one or both eyes.
Hormonal imbalances are also common, arising from pressure on the pituitary gland or hypothalamus, which regulate hormone production. This can result in a wide array of endocrine dysfunctions such as growth problems in children, altered body weight, or irregular menstrual cycles in women. Specific issues include hypothyroidism due to insufficient thyroid-stimulating hormone, adrenal insufficiency from reduced ACTH, or diabetes insipidus, characterized by excessive thirst and urination due to low vasopressin.
Headaches are a frequent symptom, often due to increased pressure within the skull caused by the growing mass. These headaches can be bifrontal or frontotemporal and may be accompanied by nausea and vomiting if cerebrospinal fluid pathways are obstructed. Other neurological symptoms include changes in appetite, sleep patterns, or mood, reflecting impact on the hypothalamus.
Identifying a Suprasellar Mass
Diagnosing a suprasellar mass begins with a thorough clinical evaluation, including a detailed medical history and neurological examination. Imaging techniques are essential for visualizing these growths and determining their characteristics. Magnetic Resonance Imaging (MRI) is the most sensitive imaging test for detecting pituitary tumors and other suprasellar masses. MRI with intravenous contrast material is often used to enhance the mass’s visibility and its relationship to surrounding structures.
Computed Tomography (CT) scans also identify larger suprasellar masses and are useful for evaluating bony structures and detecting calcifications within a tumor, characteristic of certain types like craniopharyngiomas. While CT scans offer less soft tissue detail than MRI, they can be used if MRI is not feasible.
Beyond imaging, blood tests are commonly performed to assess hormone levels, especially when hormonal imbalances are suspected. These tests can identify overproduction or underproduction of hormones regulated by the pituitary gland or hypothalamus, helping to classify the type of mass, such as a hormone-secreting pituitary adenoma. Visual field tests are also conducted to precisely map any visual deficits caused by compression of the optic pathways. In some cases, a biopsy, involving the surgical removal of a tissue sample for microscopic examination, may be necessary to definitively determine the exact type and nature of the mass, particularly if imaging results are inconclusive or suggest a less common type of lesion.
Approaches to Treatment
Treatment strategies for a suprasellar mass are individualized, depending on the mass type, size, location, and patient health. A multidisciplinary team, including neurosurgeons, endocrinologists, and radiation oncologists, often collaborates to develop the most appropriate plan. The main goals are to remove or reduce the mass, alleviate symptoms, and preserve or restore neurological and hormonal functions.
Surgical removal is a primary treatment approach for many suprasellar masses, particularly if they are causing symptoms due to compression of nearby structures. Two common surgical techniques are the transsphenoidal approach and craniotomy. The transsphenoidal approach is a minimally invasive procedure performed through the nose or upper lip, often preferred for pituitary adenomas with suprasellar extension. A craniotomy, an open surgical procedure involving an incision in the skull, may be necessary for larger or more complex masses, or those not accessible via the transsphenoidal route. The extent of surgical removal aims to be as complete as possible while safeguarding surrounding tissues.
Radiation therapy is another option, often used when complete surgical removal is not possible, for residual tumor after surgery, or for recurrent masses. It uses high-energy beams to destroy tumor cells or inhibit their growth. Types include conventional fractionated radiotherapy, which delivers radiation in small doses over several weeks, and stereotactic radiosurgery, such as Gamma Knife, which delivers a single, highly focused dose to small tumors. This precise targeting minimizes damage to healthy brain tissue.
Medical management also plays a role, particularly for hormone-secreting tumors or to address hormonal deficiencies. Certain medications, like dopamine agonists, can shrink prolactin-secreting pituitary adenomas and normalize hormone levels. Hormone replacement therapy is often administered to compensate for any pituitary deficiencies caused by the mass or its treatment, such as thyroid hormone for hypothyroidism or cortisol for adrenal insufficiency.
Prognosis and Follow-Up
The prognosis for individuals with a suprasellar mass varies, influenced by several factors. The specific type of mass, whether benign or malignant, its size, and responsiveness to treatment impact the outcome. For many benign masses, such as pituitary adenomas and craniopharyngiomas, surgical removal can lead to favorable outcomes, with symptoms improving or resolving. Complete removal also impacts long-term prognosis.
Long-term follow-up care is necessary to monitor for mass recurrence or to manage ongoing symptoms and hormonal imbalances. This involves regular imaging, such as MRI scans, to detect mass regrowth. Hormonal monitoring through blood tests is often continued to ensure balanced hormone levels and adjust any necessary hormone replacement therapies. Consistent monitoring ensures early detection of changes and allows for timely intervention, contributing to better long-term management and quality of life.