What is Craniopharyngioma?
Craniopharyngiomas are rare, non-cancerous brain tumors. These tumors typically develop in a specific area of the brain known as the suprasellar area but can spread to other parts, such as the hypothalamus, the optic nerves, other nerves in the brain, brain ventricles, and major blood vessels. They can cause a variety of symptoms which may include headaches, feeling sick, vomiting, vision problems, and hormone disturbances.
Treating these tumors can be challenging for doctors, as these are usually dealt with by various experts, such as brain surgeons, eye and brain specialists, brain disease specialists, hormone specialists, and pediatricians. Additionally, surgeries to completely remove these tumors can be very hard because of their location and penetration into surrounding structures.
Furthermore, these tumors can lead to the development of numerous complications which significantly impact the patient’s quality of life. Possible complications include a complication where the pituitary gland functions poorly, affecting hormonal balance (panhypopituitarism), vision issues, obesity, and mental health problems.
What Causes Craniopharyngioma?
There are two main beliefs about how craniopharyngioma (a type of brain tumor) forms: the embryonic theory and the metaplastic theory. These theories connect with the two different types of craniopharyngiomas, known as adamantinomatous craniopharyngioma (ACP) and papillary craniopharyngioma (PCP).
The embryonic theory is connected with the development of ACP, which is a more common type and can affect people of all ages. This theory revolves around a part of the early development of our bodies, when an area called Rathke’s pouch grows towards the part of the brain, where it eventually forms the pituitary gland (a small organ in the brain). Sometimes, this pouch doesn’t completely disappear, and leftover cells can grow into a craniopharyngioma. The cause of this growth could be due to specific changes in a gene named CTNNB1, leading to unusual cell growth and tumor formation.
The metaplastic theory is connected with the development of PCP, a type of craniopharyngioma which is mainly seen in adults. According to this theory, certain cells within the pituitary gland can change and cause a tumor to form. An alteration in a gene named BRAF has been linked with this process. This change may activate certain cellular pathways often overactive in cancer.
Risk Factors and Frequency for Craniopharyngioma
Craniopharyngioma is a condition with an occurrence rate of about 0.5 to 2 instances per million people per year. It can be found in individuals of any age but it’s typically known as a pediatric disease, making up 1.2 to 4% of all tumors found in the brain. In fact, half of all craniopharyngioma cases are diagnosed in adults. The condition often shows up most in two age groups – 5 to 14 years and 50 to 74 years. It’s worth noting that the chance of getting this condition does not vary based on one’s gender, race, or location. However, only two families have ever reported cases of craniopharyngioma running in the family.
Craniopharyngioma is known to come back about 50% of the time after treatment. Despite this high recurrence rate, the survival rate is also high. Five years after diagnosis, 83% to 96% of patients are still alive. This survival rate is 65% to 100% for 10 years after diagnosis. But it is important to keep in mind that almost every patient experiences some negative health effects as a result of this condition.
Signs and Symptoms of Craniopharyngioma
Craniopharyngiomas are tumors that grow slowly and are often diagnosed after symptoms develop due to the tumor pressing on nearby structures in the head. These symptoms can help indicate where the tumor is located.
- Headaches: Roughly half of the patients report experiencing headaches. These can be due to a rise in pressure within the brain, often causing nausea and vomiting, or irritation of the membranes surrounding the brain and spinal cord caused by fluid from the tumor.
- Visual Symptoms: Between 62% and 84% of patients will have vision-related issues. The most frequent problem is partial vision loss on the same side of both eyes, often caused by pressure on the optic nerves. Dysfunction of the optic pathway is found in 50-75% of patients.
- Hormonal Deficiency: When initially diagnosed, 40-87% of patients show at least one hormonal deficit. In adults, 40% will show a deficiency in gonadotropins, leading to missed periods in women and reduced sexual drive and erectile dysfunction in men. Growth hormone deficiency is found in 85% of patients, resulting in non-specific symptoms such as weight gain, excess weight in the body’s midsection, and fatigue. Nearly 25% of patients will have a deficit of adrenocortical hormone, leading to weight loss, widespread joint pain, dizziness, and low blood pressure. Thyroid-stimulating hormone (TSH) deficiency can be seen in 25% of patients with symptoms including weight gain, fatigue, intolerance to cold, and constipation. Approximately 20% of patients will present symptoms of diabetes insipidus due to vasopressin deficiency, including excessive urination and extreme thirst.
Testing for Craniopharyngioma
Diagnosing craniopharyngioma, a certain type of brain tumor, usually requires a team approach. This can involve specialists such as an endocrinologist, neuro-opthalmologist, and neurosurgeon.
Imaging techniques, including Computerized Tomography (CT) scans and Magnetic Resonance Imaging (MRI), play a crucial role in the process. The choice can depend on the patient’s individual symptoms. MRI is often the first choice in identifying craniopharyngiomas or other tumors in the pituitary gland. This is because it gives a clearer picture of the tumor, showing exactly where it’s located and how it’s affecting nearby areas. The different parts of the tumor, such as the solid, cystic (fluid-filled), and calcified (hardened) parts, can help in making an accurate diagnosis. While both CT and MRI can show the fluid-filled area, the hardened parts are usually more visible on CT scans.
In addition to imaging, people with visual disturbances will usually need a thorough visual examination. This would be carried out by a neuro-opthalmologist and would include testing the clarity and range of your vision.
Another critical step is checking for any hormone imbalances. This involves a series of blood and urine tests which can include measuring levels of different hormones such as cortisol, ACTH, TSH, T4, FSH, estradiol (in females), testosterone (in males), GH, insulin-like growth factor-1, and prolactin. It could also involve testing sodium levels and how concentrated your urine is. In some cases, where the cortisol results are unclear, additional testing like a cosyntropin stim test might be done.
Treatment Options for Craniopharyngioma
Craniopharyngiomas are challenging to treat due to their position and how they infiltrate surrounding brain structures. Multiple treatments exist such as surgery, radiotherapy, and intracystic therapy. The selection of treatment radically depends on the individual patient’s age, health conditions, the tumor’s location, type and invasiveness, and the expertise of the neurosurgeon. Currently, there is no universally agreed-upon treatment plan.
Before surgery, it’s crucial to address any hormonal deficiencies a patient may have, such as adrenal insufficiency and hypothyroidism. This can be done with glucocorticoid medication, usually hydrocortisone or prednisone, and thyroid hormone replacement, typically using levothyroxine. If the patient is experiencing a condition called hydrocephalus, they may need a temporary or permanent shunt to drain excess cerebrospinal fluid (CSF).
Surgery is typically the first line of treatment to provide a firm diagnosis, alleviate neurological deficits, pituitary dysfunction, and treat hydrocephalus. The surgical approach can vary based on the tumor’s location, commonly involving an endonasal transsphenoidal method or a transcranial method. However, the extent of surgery is controversial. Total removal of the tumor can lead to a higher risk of post-surgical complications, but does not significantly affect recurrence rates.
Grading systems classify craniopharyngiomas to help decide the best surgical technique. For example, the Kassam et al. system classifies tumors based on their positioning in relation to a piece of brain tissue called the infundibulum.
After surgery, patients need close monitoring for potential CSF leaks. Managing hormonal deficiencies is also crucial in the recovery process. After surgery, patients may require stress dose steroids, and should undergo routine testing for cortisol levels, sodium, urine osmolarity, and thyroid function. Checking sex hormone and growth hormone levels after three months post-surgery is also necessary.
Radiation treatment may be needed if the disease is not completely eradicated or to prevent recurrence. Despite reducing mortality rates, radiation hasn’t been proven to reduce recurrence and is typically used as an additional method to surgical intervention.
Intracystic therapy, which involves injecting toxic substances to shrink the tumor, is mainly used for purely cystic craniopharyngioma. However, this method has limited supporting data and risks severe neurotoxicity due to possible leakage of the treatment substance.
What else can Craniopharyngioma be?
- Arachnoid cyst (fluid-filled sac in the brain or spine)
- Brain tumor (abnormal growth in the brain)
- Epidermoid tumor (type of slow-growing brain tumor)
- Langerhan cell histiocytosis (a rare type of cancer that can damage tissue or cause lesions to form in one or more places in the body)
- Leptomeningeal cancer (cancer spread to the layers of tissue that cover the brain and spinal cord)
- Meningitis (an inflammation of the protective membranes covering the brain and spinal cord)
- Migraine (a severe type of headache)
- Multiple sclerosis (an autoimmune disease that affects the brain and spinal cord)
- Optic gliomas (a type of brain tumor that affects visual pathways)
- Pituitary adenoma (a type of noncancerous tumor in the pituitary gland)
- Pseudotumor cerebri (a condition that mimics the symptoms of a large brain tumor, but no tumor is present)
- Rathke’s cleft cyst (a noncancerous growth near the pituitary gland in the brain)
What to expect with Craniopharyngioma
The outcome for individuals with craniopharyngiomas, a type of brain tumor, greatly depends on the tumor’s size, type, surgical treatment method, and the extent of damage to the hypothalamus and endocrine system. Generally, the overall survival rate ranges between 80 and 95% five years after diagnosis.
Younger individuals usually have a positive outcome, while the prognosis is not as promising for individuals over the age of 65. It’s important to note that women with this condition may also experience additional health issues such as strokes, heart-related events, and challenges with social interaction and mental wellness.