Introduction
Central nervous system germ cell tumors are rare brain neoplasms, divided into germinomas and non-germinomatous germ cell tumors. Roughly two-thirds of cases are germinomas, which are more prevalent. They frequently have high survival rates because they usually react favorably to therapies like radiation, chemotherapy, or a mix of the two. While non-specific symptoms and delayed presentations on scans can make diagnosis difficult, it is based on clinical presentation, imaging, and evaluation of tumor markers.
Usually found in the pineal (region located in the middle of the brain) or sellar-suprasellar (situated between the temporal lobe's uncus, under the hypothalamus, and above the sella turcica) regions, germinomas can also occasionally be found in the basal ganglia (responsible for motor controls and emotional behavior), and thalamus (information center of the brain). An early diagnosis is essential, frequently necessitating a biopsy for histological confirmation. Even with cutting-edge imaging methods, tumor evidence might not become visible for years. Prompt identification is essential for initiating therapy promptly, which lowers morbidity and death.
What Is the Epidemiology of Intracranial Germinoma?
Due to their rarity and national differences in demography, genetics, and environmental variables, intracranial germinomas' frequency and distribution patterns are yet unknown. Roughly two-thirds of intracranial germ cell tumors (iGCTs) are germinomas, which tend to occur in either the sellar or suprasellar region in females or the pineal region in males.
What Are the Clinical Presentations of Intracranial Germinoma?
Known for their infiltrative growth, germinomas can cause weakness, irritability, headaches, nausea, vomiting, changes in mental status, endocrine abnormalities, and seizures, among other symptoms. Stunted growth occasionally occurs, and there may be problems with sexual development in certain situations. The subjective and unclear nature of the symptoms, which can take weeks to years to correlate, frequently contributes to the delayed diagnosis of malignant cancers because of their slow growth. These vague symptoms, which are more common in teenagers and young adults, could be misdiagnosed as psychosomatic problems, delaying diagnosis and treatment. Tumor size, location, and effect on surrounding tissues are directly related to clinical presentation.
Sellar Germinoma
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When a sellar germinoma grows, it affects surrounding structures and causes a variety of endocrine problems, which leads to clinical symptoms. Germinomas are more likely than craniopharyngiomas (central nervous system tumors) to cause endocrinopathy (problem of the hormone) due to malfunctioning or destroyed pituitary and hypothalamic glands. In cases of severe hypothalamic dysfunction, increased prolactin output may not be the cause of galactorrhea (breast milk production that is unrelated to pregnancy or nursing).
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Multiple endocrine inadequacies caused by these tumors frequently impair growth, puberty, sexual development, and normal menstruation. Diabetes insipidus (DI), which is characterized by excessive urine and thirst, is present in over 90 percent of cases and drives many patients to seek medical care. Optic chiasm (permits the occipital cortex of the opposing eye to perceive vision from one side of both eyes) invasion or compression can result in headaches, nausea, vomiting, and visual abnormalities such as reduced acuity (details) and constricted visual fields. Some people may not have visible problems right away when they are first diagnosed.
Pineal Germinoma
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Clinical symptoms of pineal region germinomas depend on how the tumor interacts with surrounding intracranial structures. Patients usually have shorter-lasting symptoms because even minor lesions have the potential to squeeze the cerebral aqueduct. Initial symptoms such as headaches, nausea, vomiting, and vision abnormalities are caused by elevated intracranial pressure.
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Ataxia (muscle control becomes poor, leading to involuntary movements), dyskinesia, and vertigo (dizziness, commonly characterized as a spinning or moving feeling) are neurological abnormalities. Midbrain compression causes a unique cluster of symptoms called Parinaud's syndrome, which includes upward gaze paralysis, light-near dissociation, and convergence-retraction nystagmus. Approximately 75 percent of patients with malignancies in the pineal area experience this condition. About 25 percent of individuals also have seizures and behavioral abnormalities.
Basal Ganglia and Thalamus Germinomas
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Unlike those in the sellar and pineal areas, basal ganglia and thalamus germinomas have a gradual onset and sluggish progression. Variable durations occur from a month to many years before a conclusive diagnosis due to the disparity between tumor size and symptom severity.
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The first signs in this area are irregular cognition and changes in mental state. Slowly progressing neurological conditions such as hemiparesis (weakness or immobility on a single side of the body, making it difficult to carry out daily tasks like dressing or eating), dystonia (an involuntary contraction of the muscles caused by a movement problem), stiffness, bradykinesia (with continuous movement, the speed and the movement slow down occasionally leading to halts or pause), or dyskinesia (uncontrolled, involuntary movement, or dyskinesia, can develop after taking Levodopa for an extended period or having Parkinson's disease) are caused by involvement of the extrapyramidal system (a network of neural connections in the brain that regulate involuntary movements and preserve posture). In contrast to tumors in other places, these instances usually do not exhibit endocrine problems.
What Is the Treatment of Intracranial Germinoma?
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Radiotherapy - Since germinomas are very radiosensitive, whole-brain or whole-ventricular radiation therapy, which includes craniospinal irradiation (CSI), has been used to treat them to reduce the possibility of spinal metastases. With a 90 percent overall survival rate at ten years, this strategy has historically produced strong control rates. As a result of the possible late-onset side effects from irradiating a big enough craniospinal volume, alternate therapies with lower CSI doses and fields were investigated.
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Chemotherapy - Chemotherapy has been a mainstay in the treatment of ovarian and testicular germ cell cancers, which has led to research into its possible use as a substitute for radiation therapy in the case of germinomas. This investigation aimed to lessen radiation's harmful long-term effects, particularly on younger people. To determine if chemotherapy alone is a feasible treatment for intracranial germinomas, three multicenter worldwide CNS GCT trials were conducted. All of these studies, however, showed that for patients with germinomas, radiation alone or in conjunction with chemotherapy is more effective than intense chemotherapy alone.
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Role of Neurosurgery in the Treatment of Germinoma - Maximum tumor debulking was initially considered secondary in germinoma cases due to their high radiosensitivity and associated morbidity with open neurosurgical procedures in the suprasellar and pineal regions. Modern neurosurgical methods, such as intraoperative neuro-navigation MRI (magnetic resonance imaging) machines and surgical microscopes, have considerably decreased death and morbidity, shortened hospital stays, and enhanced the quality of life following surgery for patients with germinoma.
The infratentorial-supra cerebellar approach is useful for pineal germinomas, and endoscopic biopsies are appropriate for tumors that coexist with hydrocephalus (a disorder where the brain's ventricles, which hold fluid, accumulate an excessive amount of cerebrospinal fluid (CSF). Transcranial techniques (pterional or supraorbital craniotomy) and transsphenoidal techniques (direct perinasal, sublabial, or Para septal) are used in suprasellar area procedures. Since tumor removal in pineal, neurohypophyseal (hormonal secretion center for oxytocin and vasopressin), or hypothalamic areas is influenced by important vascular and neuronal anatomy, the effect of neurosurgical intervention on germinoma outcomes is still unknown.
What Is the Prognosis of Intracranial Germinoma?
Since germinal centers respond so well to radiation and chemotherapy, they typically have good cure rates and high survival rates over long periods (ten to 20 years). New research has unveiled novel treatment approaches with impressive three-year survival rates. However, the prognosis can vary depending on the location of the tumor and the patient's age at diagnosis; adult patients with multifocal lesions tend to have worse outcomes. Post-treatment patients have a higher death rate than healthy controls, and research reveals several late consequences related to radiation therapy, such as neurocognitive disorders, secondary cancers, and vascular disorders. These possible late consequences in survivors of germinoma underscore the importance of long-term surveillance.
Conclusion
Intracranial germinoma is a rare brain tumor. However, because survival rates have increased, more people are becoming aware of the long-term effects of radiation on survivors. Thus, it is essential to comprehend the clinical presentation, histology, diagnostic techniques, tumor location, epidemiology, and treatment approaches of intracranial germinomas.
