Brain Metastases: Symptoms, Tests, and Care

Brain metastases are deposits of cancer that began in another organ and have travelled to the brain. They are not a primary brain tumor. A melanoma deposit in the brain is still melanoma, and the drugs that work against melanoma are still the ones that matter.

Between 10 and 26 percent of people who die of cancer are found to have brain metastases. MedlinePlus names lung, breast, melanoma and kidney cancer as the most common sources. Prostate and colon cancer rarely spread to the brain, and StatPearls adds head and neck cancers to that rare list.

The trouble is rarely the deposit alone. Around each one, the brain swells with fluid. This swelling is called edema, and inside a rigid skull there is nowhere for it to go. Much of what you feel comes from that pressure, which is also why steroids can work so fast.

Call emergency services (911 in the US, 999 or 112 in the UK) for any of these.

A first seizure, or any seizure that is different from usual:

• Stay with the person. Lower them to the floor and clear hard or sharp objects away.
• Cushion the head. Loosen anything tight at the neck.
• Turn them on their side so that vomit cannot go into the lungs.
• Do not put anything in the mouth. Do not hold them down.
• Note the time it starts.

Call 911 if it is their first ever seizure, if it lasts more than 2 to 5 minutes, if another one starts soon after, if they do not wake up and behave normally afterwards, or if anything about it is different from their usual pattern. A new seizure is one of the symptoms MedlinePlus lists for a metastatic brain tumor, so it is worth knowing the steps before you need them.

Rising pressure inside the skull:

• Headache that is new, severe, or different, especially one that is worse in the morning, worse lying flat, or worse when you cough, sneeze, bend or strain.
• Vomiting, often without feeling sick first, and sometimes with relief afterwards.
• Getting harder to rouse, unusually drowsy, or confused.
• Double vision, blurring, or losing part of the visual field.
• One pupil bigger than the other. This is a late and dangerous sign.

Also go straight in for:

• New weakness or numbness on one side of the face, arm or leg.
• New trouble speaking, finding words, or understanding speech.
• A sudden change in personality or behavior.
• Unsteadiness, falls, or a new inability to walk.
• A temperature of 38.0 °C / 100.4 °F or higher. The CDC uses 100.4 °F and the NCI uses 100.5 °F. Use the lower number.

Do not stop or reduce steroids or antiseizure medicine on your own, even if you feel better. Tapering is a decision for the team that started them.

Normal pressure inside an adult skull is about 7 to 15 mm Hg lying down. The skull is a sealed box holding brain, blood and fluid. Add a tumor and its swelling and pressure climbs, because nothing can expand outward.

If pressure keeps rising, brain tissue is pushed toward the only openings available. This is called herniation, and it can be fatal within hours. Warning signs are a falling level of consciousness, a pupil that stops reacting, a slowing pulse with rising blood pressure, and irregular breathing. This is not a same-week problem or a same-day problem. It is a now problem.

MRI of the brain with contrast dye is the test of record. Fine-slice MRI with contrast is described as the gold standard, because it shows how many deposits there are, exactly where they sit, and how much swelling surrounds each one. CT is faster and is often used first in an emergency, but it misses small deposits.

Sometimes a biopsy or removal of one deposit is needed, particularly when there is a single lesion, or when the brain finding does not fit the known cancer. Your team may also test the deposit for the same genetic markers used to choose drugs elsewhere in the body.

Steroids are usually the first thing given, because they shrink the swelling rather than the tumor. Dexamethasone is the usual choice. StatPearls gives one dosing regimen as a 10 mg loading dose into a vein followed by 4 mg every six hours, tapered after the initial response; your own dose is set by your team. Relief can begin within a day. Expect side effects: raised blood sugar, disturbed sleep, hunger, mood swings, thin skin, and muscle weakness in the thighs with longer use.

Stereotactic radiosurgery aims many narrow beams at each deposit, sparing the brain around it. StatPearls says standard SRS is reserved for lesions under 3 cm across. It is used for people with a limited number of deposits and reasonable day-to-day function. StatPearls also notes the decision between SRS and whole brain radiotherapy should not rest on lesion count alone: a total cumulative volume of 12 to 13 cubic centimetres may be the better guide, and more than ten deposits have been treated with SRS.

Whole brain radiotherapy treats the entire brain, often 30 Gy in 10 sessions, or shorter courses such as 20 Gy in 5 for people who are less well. It reaches deposits too small to see. The cost is memory and thinking: studies show a mean 30 percent decline on word-learning tests. Techniques that spare the memory centers, combined with the drug memantine, are used to reduce that harm.

Surgery is used for a single large deposit, one causing dangerous pressure, or when tissue is needed for diagnosis.

Drug treatment matters more than it once did. Several targeted drugs and immunotherapies now cross into the brain and shrink deposits there. Ask specifically whether your cancer has a marker with a brain-active drug.

Ask who to call, and write the number on the fridge, not only in a phone. Teach the people you live with the seizure steps above before you need them.

Ask about driving. Rules differ by country and state, and a seizure or a new deficit almost always means a legal pause. Ask about work, ladders, swimming alone, and cooking with hot oil, since a seizure in the wrong second causes the injury.

Keep a symptom diary with dates: headaches, word-finding trouble, dropped objects, near-falls. A pattern over two weeks tells your team far more than one bad morning.

• StatPearls (NCBI Bookshelf) — Brain Metastasis
• StatPearls (NCBI Bookshelf) — Increased Intracranial Pressure
• StatPearls (NCBI Bookshelf) — Palliative Radiation Therapy for Brain Metastases
• MedlinePlus (National Library of Medicine) — Metastatic brain tumor
• MedlinePlus (National Library of Medicine) — Seizures
• National Cancer Institute — Central Nervous System Tumors Treatment (PDQ) - Health Professional Version
• National Cancer Institute — Metastatic Cancer
• Centers for Disease Control and Prevention — Fever and Cancer Treatment