What is the most common and serious complication of a significant head injury?

Medical and neurological complications determine the final functional outcome, community reintegration as well as employment potential after a traumatic brain injury. Therefore, it is important to recognise the potential risks of those pathologies and to follow evidence based protocols to minimise the risk and extent of secondary complications. 

The long-term physical, cognitive, and behavioural complications are both related to the direct injury to the brain and also to the influence of central nervous system dysfunction and trauma on other organs and system. Several complications can occur immediately or soon after a traumatic brain injury, but others might not be recognised until the rehabilitation stage. Severe injuries increase the risk of a greater number and more-severe complications.

Presence of complications and injury related impairment impacts the quality of life of a person living with a traumatic brain injury. These problems can cause frustration, conflict and misunderstanding of people with a traumatic brain injury as well as family members or friends. [1] An individual’s risk of suicide as well as mood and anxiety disorders might be increased due to a combination of symptoms and neuropsychiatric factors which are often aggravated by the trauma.

Medical complications include:

Traumatic brain injuries involving skull fractures or penetrating wounds can result in meninges damage. This can result in bacterial infection of the brain. An infection of the meninges (meningitis) could spread to the rest of the nervous system if not treated.

Sepsis, or multiple organ dysfunction syndrome are the leading causes of late morbidity and mortality in traumatic brain injury. The catecholamine surge that follows a systemic insult is directly involved in the regulation of cytokine expression in situations of acute stress producing a worsening clinical condition and, ultimately, a poor outcome. The trauma-induced catecholamine surge affects systemic organs and contributes to organ damage. [2]

Spasticity is one of the upper motor neuron features that develops rapidly, in some cases as early as one week post traumatic brain injury, and often results in orthopaedic sequelae. [3] Mild spasticity can have some benefits like maintaining muscle bulk or enhancing gait, but moderate to severe increased muscle tone and spasm can severely impact rehabilitation outcomes, functional recovery and ability to engage in activities of daily living. Moderate to severe spasticity requires structured management protocols.

Impaired respiratory function is common following a traumatic brain injury and is primarily determined by the severity of the injury. There is a reciprocal relationship between lung function and brain function: the brain needs sufficient oxygen supply in order to operate, and the respiratory system needs instructions from the brain in order to operate.

In cases of Traumatic Brain Injury, respiratory dysfunction is the most common medical complication, with respiratory complications directly correlated with mortality, and both are related to the severity of the injury. Up to one-third of patients with severe traumatic brain injury develop Acute Respiratory Distress Syndrome (ARDS). In this syndrome, there is inflammation of the alveolar-capillary interface, which leads to fluid and proteins entering the interstitial space and alveoli. Between 20 and 30% of individuals who develop ARDS die as a result of the pulmonary infiltrate leading to respiratory failure.

Read more about Respiratory Management in Traumatic Brain Injury

Deep Vein Thrombosis and Pulmonary Embolism[edit | edit source]

Deep vein thrombosis (DVT), which refers to the formation of one or more blood clots in one of the body’s large veins and subsequent Pulmonary Embolism (PE), which is blockage of an artery in the lungs by a substance that has moved from elsewhere in the body through the bloodstream (embolism), remains a significant cause of morbidity and mortality in individuals with traumatic brain injuries and are particularly vulnerable during the first 2-3 weeks post the injury. After traumatic brain injury the incidence of DVTs is as high as 54% due to difficulties using anticoagulation in the acute post traumatic brain injury period, with prophylaxis often only available after the risk of renewed intracranial haemorrhage decreases.

Read more about Deep Vein Thrombosis and Pulmonary Embolism

Paroxysmal Sympathetic Hyperactivity (PSH)[edit | edit source]

Sympathetic hyperactivity is “the storm after traumatic brain injury", observed for weeks or months and presenting with increased sympathetic activity: heart rate increase, blood pressure increase, respiratory rate increase, sweating, hyperthermia, motor posturing. [4] The PSH is related to poor outcome and results from disconnection syndrome which is the impairment of inhibitory control over excitatory autonomic centres.

Neuroendocrine Dysfunction / Post Traumatic Brain Injury Hypopituitarism[edit | edit source]

Clinically prevalent phenomenon related to damage of the pituitary gland, a small gland that sits at the base of the brain and regulates other endocrine glands, i.e. thyroid, adrenal glands, pineal gland. Damage to the pituitary gland is most prevalent in cases with skull fracture and affects its own function as well as affects other hormones production impacting homeostasis metabolism, mood, growth, sleep and other bodily functions. Hypopituitarism has been related to the presence of depression and fatigue. The resulting thyroid malfunction relates to neuropsychiatric issues, cardiac function decrease, anxiety, diabetes insipidus. 

Heterotopic ossification, also referred to as ectopic ossification and myositis ossificans, is the formation of pathological bone in muscle or soft tissue, which if severe can lead to ankylosis and impaired function. It usually presents around the joint, predominantly in the hip, with the first signs including swelling around the joint, reduced range of motion, with or without fever, spasticity and pain, which are similar clinical signs to those of fracture and deep venous thrombosis. Ultrasound, CT Scan or Bone Scan are used to provide a definitive diagnosis of heterotopic ossification, although blood tests may also give some indication.

In traumatic brain injury the incidence has been reported between 11-76%, with a 10-20% incidence of clinically significant heterotopic ossification. It presents with abnormal formation of ectopic lamellar bone in soft tissue. The heterotopic ossification tends to form around the bigger joints such as the hip, knee and shoulder and causes a range of motion decrease with limited mobility, pain and decreased function. Timely use of prophylactic nonsteroidal anti-inflammatory drugs and diagnostic imaging modalities should be implemented early to prevent severe mobility impairment. Other approaches include use of bisphosphonates (limited evidence), radiation and physiotherapy allow mechanical improvement. Fully formed heterotopic ossification can be surgically excised when severe pain or lose of range of motion significantly impact mobility or personal care.

Read more here about the prevention and management of Heterotopic Ossification

Bladder Bowel Dysfunction and Genitourinary Complications[edit | edit source]

Among the most common complications in patients with traumatic brain injury due to ineffective communication, cognitive deficits and behavioural difficulties. Urinary dysfunction relates to detrusor overactivity and often leads to longer stay at acute services and delayed rehabilitation. At discharge those patients demonstrate poorer functional recovery. Establishing the causes (e.g. urinary tract infection), use of appropriate medication and pelvic floor exercises improve the outcome. 

Neurogenic bowel conditions can be either incontinence or constipation. 68% of individuals admitted to rehabilitation might demonstrate faecal incontinence. Hydration, fibre intake, medication and toilet training can assist with these issues. Untreated bladder and bowel dysfunction impose a risk on tissue viability and should be addressed. 

Sexual impairment related to frontal lobe damage and limbic system malfunction might present as hypersexuality, decreased sexual drive, lack of satisfaction or ejaculation dysfunction. Social and intimacy difficulties aggravate these sexual malfunctions. Resultant inappropriate sexual behaviour creates potential risks of difficulties forming relationships, aggression and criminalisation.

Endocrine and inflammatory processes after traumatic brain injury lead to excessive energy expenditure and consequent malnutrition, hyperglycaemia, hypercatabolism of proteins, lack of wound healing, muscle wasting and urinary nitrogen excretion. Enteral feeding with heavy protein supply can improve outcomes. Optimal nutrition facilitates better sleep behaviour, physical fitness, emotional status and fatigue management.

Individuals with a traumatic brain injury are at high risk of developing pressure ulcers. The National Pressure Ulcer Advisory Panel, U.S (NPUAP) defines a pressure ulcer as an area of unrelieved pressure over a defined area, usually over a bony prominence, resulting in ischemia, cell death, and tissue necrosis. [5] A pressure ulcer is localized injury to the skin and/or underlying tissue usually over a bony prominence, as a result of pressure, or pressure in combination with shear. [6] A pressure sore can develop in a few hours, but the results can last for many months and even cause death. A number of contributing or confounding factors are associated with pressure ulcers; but the significance of these factors is yet to be elucidated. Tissue injury is related to both extrinsic and intrinsic factors. Extrinsic factors include pressure, shear, friction, immobility, and moisture, while Intrinsic factors relate to the condition of the patient, such as sepsis, local infection, decreased autonomic control, altered level of consciousness, increased age, vascular occlusive disease, anemia, malnutrition, sensory loss, spasticity, and contracture.[7]

Read more here about the prevention and management of Pressure Ulcers

Sleep disturbance is an extremely common complication amongst people living with traumatic brain injury. Includes insomnia, hypersomnia, excessive daytime sleeping and impaired circadian sleep-wake patterns.[8] The impact depends on the injured area and can be treated with sleep hygiene training, daytime exercises, caffeine intake limitation, CBT and medication.

Post-traumatic Headaches are commonly present after traumatic brain injury. Tension-type headaches are the most common form, but exacerbations of migraine-like headaches are also frequent. Headaches are often a long-term problem.

Neurological complications include:

Post-traumatic seizures frequently occur after moderate or severe traumatic brain injury. They may occur only in the early stages, or years after the injury (post-traumatic epilepsy). The post injury classification is:  

  • Immediate seizures (occurring within 24 h after injury) 
  • Early seizures (occur less than 1 week after injury) 
  • Late seizures (occur more than a week after injury).  


Risk Factors include:  

  • Bilateral contusion 
  • Dural penetration 
  • Subdural haematoma 
  • Multiple intracranial surgeries 
  • Midline shift > 5mm 
  • Presence of severe injury measured by GCS.  


Post-traumatic seizure relates to poor functional outcome. Phenytoin and levetiracetam are the most commonly used drugs in prevention and treatment of seizures. 

Hydrocephalus occurs when cerebrospinal fluid builds up in the cerebral ventricles causing increased pressure and swelling in the brain. As many as 70% of patients demonstrate ventricular enlargement 2 months post moderate to severe traumatic brain injury. Craniectomy, severe traumatic brain injury, older age, longer come, intracranial bleeding are possible risk factors. A plateau in rehabilitation progress or a functional decline might suggest the presence of post-traumatic hydrocephalus. Clinically a patient developing post-traumatic hydrocephalus might demonstrate headache, nausea, urinary incontinence, cognitive decline, papilledema, motor impairment. Diagnostic imaging in conjunction with a lumbar puncture are the usual diagnostic tools. The surgical implantation of a shunt to drain excess cerebrospinal fluid into the abdominal cavity is a treatment option. 

Traumatic brain injury at the base of the skull can cause damage to the nerves that emerge directly from the brain or brainstem. Cranial nerve damage may result in: 

  • Paralysis of facial muscles or losing sensation in the face
  • Loss of or altered sense of smell
  • Loss of or altered sense of taste
  • Loss of vision or double vision
  • Swallowing problems
  • Dizziness
  • Ringing in the ear
  • Hearing Loss

Visual dysfunction may present as blurred vision, sensitivity to light, reading difficulty, headaches with visual tasks, reduction or loss of visual field like hemianopsia, and difficulties with eye movements, gaze stabilisation deficits. These vision problems impact on other areas of functioning such as communication, mobility and balance. They can also impact on safety, e.g. visual field defects.

May include somatosensory loss, persistent ringing in the ears, difficulty recognising objects, blind spots or double vision, bitter taste, a bad smell or difficulty smelling, paraesthesia like skin tingling, itching, numbness or pain. The array of problems experienced requires careful assessment to inform the most effective treatment as untreated the neurosensory deficits impact on other functions like motor control and the final level of functional recovery.

Spatial neglect is a complex problem involving perception, movement and memory presenting as impaired attention to the side contralateral to the lesion. Presence of unilateral neglect severely impairs recovery. Therapeutic approaches should include teaching motor, sensory and compensatory strategies , however there is no clear evidence of clinical effectiveness or superiority of any particular approach.

Movement disorders can be demonstrated as hypokinetic or hyperkinetic phenomenon and might present as: tremor, chorea, dystonia, athetosis, ballism, myoclonus, parkinsonism, tics. [8] The movement disorder might be the only symptom or coexist with other movement or motor disorders. They can also be a side effect from medication, for example medications used to treat impaired cognition or arousal. Some pathologies like dystonia occur in acute phase post traumatic brain injury, but some like parkinsonism can occur decades after the trauma. The most common movement disorders after traumatic brain injury are tremors, dystonia, parkinsonism, myoclonus and these are more prevalent with severe injuries. The areas of the brain often involved in movement disorders are: basal ganglia, cerebellum, thalamus, subthalamus and white matter tracts. Treatments include addressing the cause, for example haematoma or hydrocephalus; through pharmacological and surgical interventions.

Dizziness / Balance Disorders[edit | edit source]

Dizziness and balance disorders are a common traumatic brain injury complication with dizziness being reported by 80% of people. The aetiology might be complex including vestibular impairment, sensory integration problems, visual or proprioceptive. Main pathologies include BPPV, central vestibular or peripheral problems, like vestibular nerve damage or injury to the semicircular canals of the ear. Physiotherapeutic treatment depends on the pathology aetiology. 

Post traumatic brain injury the restorative function of sleep is diminished, and sleep pathology is very common. Contributing factors include biochemical and structural changes to the brain especially reticular system, thalamus and hypothalamus, medicinal such as unmanaged pain, behavioural with napping during the day and caffeine intake, and can be environmental. For example where there is no clear day/night distinction in the hospital ward. Treatment approaches include sleep hygiene training, pharmacological agents such as melatonin, benzodiazepines or zolpidem, exercises and light therapy. 

Fatigue in people with traumatic brain injury have impacts that are central, for example causing difficulty with cognitive tasks (linked to caudate activation in the Basal Ganglia[9]) and peripheral resulting in musculoskeletal tiredness. The presence of fatigue can have negative impacts on the participation in rehabilitation. Treatment includes environmental adjustments and sometimes medication such as modafinil.

Behavioural and emotional changes including agitation, difficulty with self-control, lack of awareness of abilities, risky behaviour, verbal or physical outbursts, alcohol misuse, binge drinking, anxiety and depression, mood swings, irritability, anger, lack of empathy for others. All these issues can significantly impact a rehabilitation outcome and community reintegration.  These behavioural changes can have negative impacts on relationships, employment and criminal activity. The neuropsychologist and neuropsychiatrist are an integral part of the MDT working with people after brain injury and an integrated behaviour management programme needs to be followed by all the professionals and relatives involved. Post-traumatic depression is further associated with cognitive decline, anxiety disorders, substance abuse, dysregulation of emotional expression, and aggressive outbursts.

Following areas can be affected and impact on information processing, communication, movement execution and balance skills:

  • Memory: sensory memory, working memory, short term, long term, semantic memory, procedural memory, episodic memory 
  • Learning new skills and information
  • Reasoning
  • Judgment
  • Attention or concentration
  • Executive functioning problems
  • Problem-solving
  • Multitasking
  • Organisation
  • Planning
  • Decisionmaking
  • Beginning or completing tasks

Often resulting from repeated or severe traumatic brain injuries; People living with traumatic brain injury are at approximately 4 times greater risk of developing dementia and earlier in life compared to the general population. Repetitive injuries have been related to Chronic Traumatic Encephalopathy (CTE) or Dementia Pugilistica (Boxer’s Dementia) whilst a single brain injury has been related to Alzheimer’s type symptoms. The exacerbation of degenerative brain diseases following traumatic brain injury is also related to genetic background. 

Moderate to severe traumatic brain injury, can result in changes to a person’s state of consciousness, awareness or responsiveness. Different states of consciousness include:

What is the most severe complication of head injury?

Altered consciousness Moderate to severe traumatic brain injury can result in prolonged or permanent changes in a person's state of consciousness, awareness or responsiveness. Different states of consciousness include: Coma. A person in a coma is unconscious, unaware of anything and unable to respond to any stimulus.

What is the most serious head injury?

Though it isn't as outwardly visible as other forms of brain injury, a diffuse axonal injury is one of the most dangerous types of head injuries. It can lead to permanent brain damage and even death.

What is the most common cause of death in patients with head injuries?

Falls lead to nearly half of the TBI-related hospitalizations. Firearm-related suicide is the most common cause of TBI-related deaths in the United States.

What is the most common head injury?

The most common type of head injury is concussion. Concussion may or may not be associated with loss of consciousness (blackout).