Types of Brain Injuries

Summary

• There are two types of brain injuries including traumatic brain injuries and acquired brain injuries.
• Traumatic brain injuries can be further categorized as open head injuries and closed head injuries.
• Traumatic brain injuries lead to various types of medical conditions like hematoma, hemorrhage, concussion, contusion, coup and contrecoup injuries and skull fractures. 
• Various types of acquired brain injuries include meningitis, hydrocephalus, hypoxia and anoxia. 

Introduction

The human brain is undoubtedly the most fundamental organ in the human body. It controls and coordinates actions and reactions, allows humans to think and feel, and enables them to have memories and feelings contributing to all the things that make them human.

An injury to the brain can have a devastating impact on the overall human body and how the person reacts to different situations both physically and mentally (Levin and Diaz-Arrastia, 2015). Brain injuries are broadly categorized as traumatic brain injuries and acquired brain injuries.

Traumatic Brain Injuries

Brain injuries that result from an external impact are called traumatic brain injuries. Brain injuries generally result from either an open or closed injury to the skull which acts as a natural shield for the brain. 

Open head injury: In an open head injury, the skull breaks due to a strong impact from another object causing direct contact with the brain. 

Closed head injury: In a closed head injury, the impact leaves the skull unbroken with either a bump or no physical damage, but can cause an internal damage to the brain (Kothbauer, ter Poort and Sepehrnia, 2019). 

Open and closed brain injuries can lead to various medical conditions that are explained below:

Hematoma

Under hematoma (aka subdural hematoma) the blood starts clotting outside the blood vessels in the brain leading to pressure building inside the skull. The outermost layer of tissue surrounding the brain is called dura.

In subdural hematoma, blood collects between the dura and the next layer called arachnoid. This excessive pressure can result in unconsciousness and even permanent damage to the brain (Yadav et al. 2016).

Symptoms of hematoma include confusion, headache that keeps getting worse, mood swings, drowsiness and loss of consciousness. Symptoms may develop soon after the injury (acute hematoma) or days-weeks after the injury (chronic hematoma).

Hematomas generally need to be treated with surgery. There are two types of surgeries including craniotomy and burr hole surgery that is done to treat hematomas.

During craniotomy, the surgeon removes hematoma by excising a part of skull while during burr hole surgery hematoma is drained by inserting a tube through a hole that is drilled into the skull (Mondorf et al. 2009).

Hemorrhage

A hemorrhage represents an uncontrolled bleeding around or inside the brain tissues, commonly referred to as stroke. Brain hemorrhage may be intracranial (bleeding takes place inside the skull), cerebral/intracerebral (bleeding takes place around/within the brain) or subarachnoid (bleeding takes place in the small space between the brain and the thin tissue surrounding the brain).

Bleeding may disturb the normal circulation to brain that deprives brain of normal oxygen leading to stroke. Brain hemorrhage can increase pressure inside the skull that can further increase the bleeding (Zoerle et al. 2015).   

Brain hemorrhage can cause sudden headache and vomiting. It can cause numbness or paralysis of arm, leg, face or body. It may cause difficulty in swallowing, vision or maintenance of balance.

Early treatments include stabilizing breathing and blood pressure. Painkillers and antidepressants are given to brain hemorrhage patients to prevent pain. However, if there is too much bleeding then surgery may be required (Kim and Bae, 2017).     

Concussion

A concussion occurs due to external contact of an object with the skull shaking up the brain and causing it to hit against the hard walls of the skull. This can lead to a temporary loss of function for the brain. In case of stronger or repeated impacts, this can even lead to permanent loss of function as well (Hodges and Ameringer, 2019). 

Concussion causes confusion or feeling of fog, dizziness, ringing in ears, slurred speech, delayed response to questions, headache and fatigue. Patients who suffer from concussion cannot remember what happened immediately before and after the head injury.

Some patients may also experience delayed symptoms like sleep problems, sensitivity to light and noise and problem in focusing. Concussion patients are kept under observation to estimate the extent of damage caused by brain injury. Physical and cognitive rest is advised until the symptoms begin to resolve.

Analgesics especially paracetamol is advised for minimizing the risk of intracranial hemorrhage (Brody, 2019).   

Contusion

Contusion results from direct impact on the skull that causes bruises or bleeding. Contusion is often confused with concussion. Contusion is a localized brain injury while concussion is a wide-reaching brain injury caused by broad range impact on the brain.

Additionally, there is a blurry distinction between contusion and hemorrhage. However, if ⅔ or lesser tissue is bruised, it is called contusion. However, if more than 2/3 of brain tissue is damaged it is referred as hemorrhage (Khoshyomn and Tranmer, 2004).

Treatments like controlling low blood pressure, decreased sodium and increased carbon dioxide are given primarily to reduce cerebral swelling caused by contusion. However, large contusions are required to be removed through surgery.

Coup-contrecoup

Coup injuries are the contusions that occur under the site of impact. However, contrecoup refers to the contusions that are present at the location of impact on brain as well as on the opposite side of the brain.

This is caused when the impact is so severe that brain slams into the opposite side of the skull. Therefore, the brain is damaged not only at the site of impact but also in the completely opposite side of impact as well.

Coup injuries occur commonly when a moving object slams into stationary head On the other hand contrecoup injuries occur when moving head slams into a stationary object. In contrecoup injuries, the blood vessels may rupture, axon bundles in brain may be twisted and increased pressure in the head may affect the walls of the ventricles (Payne and Payne, 2019).  

Types of coup and contrecoup brain injuries

Coup and contrecoup injuries can be further categorized as focal injuries and diffuse axonal injuries. Focal injuries are restricted to a particular position of brain. However, diffuse axonal injuries may affect a wider area of the brain.

In this type of injury, there is damage to the brain cells rather than any bleeding. The damage to the cells can cause them to dysfunction and leads to swelling. However, most of such damages are not physically visible. Contrecoup injuries occur in shaken baby syndrome and road accidents.    

Skull fracture

Skull fracture is the breaking of cranial bone that protects the brain. When an external impact is strong enough to break the skull bone, this is referred to as the skull fracture. A broken skull often leads to a direct damage to the brain as well.

Skull fracture isn’t always easy to see but its symptoms include facial bruising, bleeding from ears or nostrils and swelling around the area of impact. Additionally, the patient may suffer from blurred vision, headache, stiff neck, confusion, pupils not reacting to light and nausea (Luke, 2012)). 

Skull fractures are of various types including closed fracture (skin covering the fracture area stays intact), open fracture (skin on top of fracture is ruptured and bone becomes visible), depressed fracture (skull extends or indents into the brain cavity), basal fracture (occurs in areas on lower side of skull like around eyes, top of neck, near spine etc.), linear (straight line) and comminuted (breakage in different sections).

A skull fracture is treated according to the level of severity. Mild fractures are treated with pain medicines while severe fracture may require surgeries (Thomas, de Castro and Pait, 2001).    

Acquired Brain Injuries

Apart from the head injuries, brain injuries can also result from bacterial infections and dysfunction of other components of the brain and its surrounding tissues.

However, the resulting damage from all types can be fatal for humans and should be taken seriously. Various kinds of medical conditions fall in the category of acquired brain injuries as explained below:

Meningitis

This refers to an inflammation of the membranes (meninges) lining the brain due to bacterial, viral, fungal, parasitic, amebic infection. Meningitis may also be caused due to cancers or certain drugs. Treatments of meningitis depend on the particular cause of disease. Vaccines are very effective for preventing infectious types of meningitis. 

Bacterial meningitis

Bacterial meningitis is deadly and requires immediate medical treatment. It may be caused by various bacterial strains including Streptococcus pneumoniae, Neisseria meningitidis and Listeria monocytogenes. Bacteria may spread from one person to another and through food.

These infections may spread when large groups of people gather like college campuses etc. Bacteria like E. coli and Streptococcus can be passed from mother to child during birth. S. pneumoniae spreads through sneezing or coughing while N. meningitidis spreads through throat and respiratory secretions. Doctors usually recommend healthy people to avoid contact with patients suffering from bacterial meningitis (Kim, 2010).

Viral meningitis

It is the most common type of meningitis but many people suffering from viral meningitis get better on their own without the administration of antiviral drugs. It is mostly caused by non-polio enterovirus. Less often, it is caused by influenza virus, mumps virus, herpes virus, arbovirus and lymphocytic choriomeningitis virus.

Children under the age of five are mostly affected by meningitis causing viruses and exhibit symptoms like fever, sleepiness, nausea, lack of appetite etc. Viral meningitis is diagnosed through blood tests, nose/throat swabs, stool samples and spinal cord fluid samples. If the symptoms do not go away in 7-10 days, antiviral drugs are administered to treat the disease (Chadwick, 2005).   

Fungal meningitis

It is less common as compared to bacterial and viral meningitis. It is mostly caused by Cryptococcus (spreads from soil and bird droppings), Candida, Coccidioides (spreads from soil), Histoplasma (spreads from bird droppings) and Blastomyces (spreads from soil and decaying woods).

Fungal spores may be taken in via breathing and infection spreads from lungs to brain. Premature babies and immunocompromised people are at high risk of getting fungal meningitis (Scully, Baden and Katz, 2008).        

Hydrocephalus

This results from excess supply of cerebrospinal fluid (CSF) in the ventricles of the brain leading to pressure buildup and swelling inside the brain. Hydrocephalus may be related to developmental disorder or may be inherited genetically. In addition, it may be caused by other factors like traumatic brain injuries, brain tumors, meningitis etc.

Symptoms in babies include enlarged head, vomiting, seizures, prominent veins on scalp, downward turning of baby’s eyes etc. In adults it may cause headaches, imparied cognition and vision, loss of bladder control etc. Hydrocephalus may be treated by removing fluid from the problem site.

Fluid may be decreased by inserting a device that diverts fluid away from the brain to other body parts like peritoneal cavity (Telano and Baker, 2018. In more complicated cases, surgeons insert a camera to look into brain ventricles and create a new pathway for the fluid.  

Hypoxia and anoxia

These injuries deal with the supply of oxygen to the brain. A complete disruption in supply leads to cerebral anoxia whereas a partial disruption causes cerebral hypoxia. In both cases, blood may be travelling to the brain but it is devoid of oxygen.

In a few minutes, brain cells may die thereby causing lasting damage to the brain functioning. Symptoms include sudden sweating, impaired vision and sudden euphoria. Hypoxia and anoxia may be caused by traumatic brain injuries, heart attack, poisoning, asthma attacks etc.

There are several types of hypoxia and anoxia including anemic anoxia (total hemoglobin provided decreased amount of oxygen to the brain cells), toxic anoxia (inhalation of toxic substances, drugs, excessive alcohol or anaesthesia), anoxic anoxia (suffocated areas or high altitudes) and ischemic hypoxia (decreased blood pressure or reduced blood flow to the brain) (Wilson and van Heugten, 2017).    

Conclusion

In conclusion, brain injuries include various types and subtypes that need to be understood for appropriate treatment of the particular disease. Both traumatic and acquired brain injuries require immediate treatments to prevent damage to the sensitive yet most important part of the body i.e. brain.  

References

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