Minimal and Mild Traumatic Brain Injury

• For head injuries and mild brain injuries in children, see also Head Injuries in Children

Essentials

• A traumatic brain injury is a functional disorder of the brain caused by an external force. More severe injuries also involve structural lesions.
• The diagnosis of traumatic brain injury is based on the score obtained on the Glasgow Coma Scale (GCS) Prehospital Emergency Care, the length of the memory gap after the injury, the duration of unconsciousness, and findings on brain imaging.
• Concussion is the mildest and most common form of traumatic brain injury.
• In the international context, a concussion is regarded as a minimal traumatic brain injury
  • In concussion, the disturbance caused by head injury to the brain function is transient and of brief duration and not associated with longer than momentary unconsciousness or amnesia or with findings in imaging studies.
• Mild traumatic brain injuries should be recognized, the patient's condition assessed (incl. any need for emergency head imaging), and the appropriate setting for follow-up chosen accordingly.
• The event history and the patient's condition should be documented in sufficient detail in the medical records, with special emphasis on the length of the memory gap, the length of any unconsciousness, the GCS score and neurological findings.
• Acute complications should be excluded. If there are symptoms or findings suggesting intracranial haematoma, the patient should immediately be referred as an emergency to a unit where computerized tomography (CT) of the head can be performed.
• Magnetic resonance imaging (MRI) of the brain is essential for defining the extent of the lesion, for documentation and for differential diagnosis if symptoms have continued for a longer time.
• In a patient with mild traumatic brain injury, the symptoms usually subside within a few weeks (no longer than a few months) from injury.
• If prolonged symptoms (beyond 2-4 weeks) occur, the patient should be referred for further neurological examination.

Symptoms of brain injury

• In mild brain injury the duration of unconsciousness is no more than a few minutes (30 minutes, at the most), and the length of PTA does not exceed 24 hours.
  • PTA covers the period after the injury of which the patient has no continuous memory. This period typically leaves a permanent memory gap because during PTA the brain cannot form permanent memory traces of any events.
• In addition to possible disturbance of consciousness (incl. disorientation) and amnesia, the symptoms of a mild brain injury may include headache, vomiting and balance problems.
• A new, local neurological deficit that is temporally and anatomically related to the injury suggests a contusion-level injury Brain Contusion.

Examination, follow-up and further treatment Psychological Treatment for Anxiety in People with Traumatic Brain Injury

• Assess whether the energy involved was sufficient to be the cause of the brain injury.
• Assess the patient's orientation to time, place and person at presentation and during follow-up.
• Assess any PTA and its length by repeated, detailed questions.
• Enter the exact time of injury and the end of PTA in the patient record.
• In the clinical examination, exclude any localizing neurological symptoms and findings, e.g. paralysis of the extremities, disturbance of speech, impairment of vision or diplopia, nystagmus, loss of hearing or facial paresis.
• Pay attention to any external injuries particularly in the area of the head or face, and enter any findings in the patient record.
• Palpate and inspect the skull to find any signs of fracture.
• Subcutaneous haematomas around the eyes or behind the ears may suggest a skull base fracture. Clear liquid running from nose or ear may suggest a CSF leakage caused by a fracture in the base of skull.
• Skull x-ray is not helpful when assessing the need for treatment of an acute brain injury.
• Emergency cranial CT is indicated if a skull fracture, cerebral haemorrhage or contusion is suspected.
• The indications of a CT scan of the head after a head injury (even one of the following is enough)
  • GCS < 13 when assessing the patient at the emergency department for the first time
  • GCS < 15 at the emergency department two hours after the injury
  • Suspected open or depressed skull fracture
  • Sign of a basal skull fracture
  • Post-traumatic convulsive seizure
  • Focal neurological deficit
  • More than one episode of vomiting after the injury
  • Anticoagulant medication
    • If the patient uses concomitantly more than one antiaggregatory drugs, a head CT scan should be readily performed.
  • Amnesia or unconsciousness AND one of the following:
    • age ≥ 65 years
    • known blood coagulation disorder
    • dangerous mechanism of injury (a pedestrian knocked down by a motor vehicle, a person flown out of a vehicle, falling down from the height of over 1 meter or (in a staircase) of more than 5 steps, for example)
    • retrograde amnesia of over 30 minutes
• Emergency consultation of a neurosurgeon is warranted to define the line of treatment of acute intracranial injury detected by CT.
• A patient with mild brain injury can be safely discharged if the following criteria are fulfilled:
  • No fresh lesions in cranial CT or no indications for a CT scan
  • GCS score 15
  • Post-traumatic amnesia (PTA) has subsided.
  • No other injuries requiring hospital care
  • Post-traumatic symptoms (e.g. headache, nausea, dizziness/vertigo) are mild.
• Inebriation does not exclude mild brain injury; intoxicated patients should be examined and followed up with special care.
• Patients should be monitored at a health care unit for at least 24 hours after mild brain injury, if:
  • intoxication prevents reliable neurological assessment, even if cranial CT is normal, or
  • the patient has severe symptoms (e.g. headache, vertigo, nausea) even though cranial CT is normal.
• Patients with mild brain injury should be monitored as follows if cranial CT has not been performed or until it is; check the level of consciousness (GCS), pupils (size / reaction to light), neurological status and vital functions (blood pressure, heart rate, respiratory rate and oxygen saturation):
  • 0-6 h from injury - every 30 minutes
  • 7-12 h from injury - hourly
  • 13-24 h from injury - every 2 hours.
• If the neurological status gets worse (new neurological finding/symptoms and/or GCS score decreased by ≥ 2) during follow-up, the patient should be referred to a unit with emergency cranial CT available or the already performed CT scan should be repeated.
• Most patients who require referral to a hospital require a cranial CT scan. Radiology may reveal that a brain injury appearing clinically mild is a brain contusion.
• Refer for hospital treatment (follow-up):
  • Children whose condition is abnormal or whose parents are clearly worried about the situation (see also Head Injuries in Children)
  • Heavily intoxicated patients
  • Symptomless patients who have sustained a high-energy injury
  • Patients with multiple injuries
  • Patients with exceptionally severe symptoms (e.g. headache and/or vomiting)
  • Patients with abnormalities in the neurological clinical examination
  • Patients with a fresh lesion detected in cranial CT.
• Further treatment
  • Symptomatic medication
    • Primarily paracetamol for headache
    • Additionally NSAID for pain, if needed, when 24 hours have passed after the injury.
    • Hypnotics and other sedatives should be avoided during the first days.
  • Rest or at least less strain for 24-48 hours, and subsequently gradual increase in physical and mental exertion
  • After a concussion, the patient may usually return to work after 1-3 days.
  • After a mild brain injury, the duration of sick leave should be 1-2 weeks depending on the character of the work tasks.
  • Written patient information concerning typical symptoms following the injury and recovery supports the healing process.
• The patient should be contacted or a follow-up visit arranged about 1-2 weeks after the injury. If the symptoms persist, necessary further investigations should be scheduled.
• Patients with mild brain injury usually become symptom-free and return to work.
• Patients with prolonged symptoms require outpatient neurological examinations in a hospital (e.g. special clinic for traumatic brain injuries).
  • The investigations in the initial phase typically include MRI of the brain and multidisciplinary assessment, including neuropsychological testing.
  • Cranial MRI should be carried out urgently (within 2-3 weeks), if the cranial CT is normal and at least one of the following criteria is met:
    • Clinically the patient has a traumatic brain injury with unconsciousness of several minutes or PTA of several hours.
    • The patient has been in a high-energy accident and has multiple injuries.
    • Cranial CT does not explain the clinical picture.
    • Due to the head trauma the patient is in immediate need of care on hospital ward, and diagnosing a brain injury in the patient based on clinical criteria is difficult or uncertain.

Long-term effects

• There is no reliable information available on cumulative adverse effects (such as increased or prolonged symptoms of recurrent injuries) or long-term effects (such as neurodegenerative diseases, incl. chronic traumatic encephalopathy) of single or recurrent concussions or mild brain injuries.
• In some cases, mild brain injuries may be associated with prolonged white matter degeneration.