Concussion symptoms can start weeks after the hit

A concussion is a brain injury: a short loss of normal brain function. A hit
to the head or the body moves the head and brain rapidly back and forth, and
the brain bounces or twists inside the skull. That produces chemical changes
in the brain and can stretch and damage brain cells.

People often call it a "mild" brain injury. It is worth being precise about
what that means: concussions may not be life-threatening, and they can still
be serious.

They are a common sports injury. Other causes are blows to the head, bumping
your head in a fall, being violently shaken, and car accidents.

The timing that catches people out

**Symptoms may not start right away. They may start days or weeks after the
injury.** Someone who walked away from a collision apparently unaffected has
not necessarily escaped one — the absence of symptoms on the day is not
evidence.

What to expect: a headache or neck pain, nausea, ringing in the ears,
dizziness, tiredness, and feeling dazed or not yourself for several days or
weeks.

When to get help urgently

Contact a health care professional if symptoms get worse, or with any of:

• Convulsions or seizures
• Drowsiness, or an inability to wake up
• A headache that worsens and does not go away
• Weakness, numbness, or decreased coordination
• Repeated vomiting or nausea
• Confusion
• Slurred speech
• Loss of consciousness

Diagnosis

A physical exam and questions about the injury, then most likely a
neurological exam checking vision, balance, coordination and reflexes,
and an evaluation of memory and thinking. Sometimes a CT scan or MRI, which
looks for bleeding or inflammation in the brain and for a skull fracture.

Recovery is rest, including mental rest

Most people recover fully, and it takes time. **Rest is what lets the brain
heal.** At the beginning that means limiting physical activity and
activities involving a lot of concentration — studying, computer work, video
games. Those bring symptoms such as headache and tiredness back, or make them
worse.

The half people skip is the second one. A person told to rest after a
concussion often stops playing sport and carries on with a full day of screens
and study, which is not rest in the sense meant here.

When your provider says it is all right, return to normal activities
slowly.

Source: Centers for Disease Control and Prevention, via MedlinePlus.