If the expression “head trauma” (TC) literally corresponds to a shock on the skull, whatever its intensity, in medical terms, head trauma corresponds to a shock whose intensity causes a disorder of consciousness, even brief. Many circumstances in life can lead to head trauma (sports, professional, car accident or road accident, domestic accidents, aggression, fall, blow on the head, firearm …).
SOME INDISPENSABLE NOTIONS
- Brain inertia
Head trauma can be mild or severe, with all possible mediators. Its severity depends on the existence of intra-cerebral lesions or the existence of an extra-cerebral hematoma, bleeding between the skull and the brain. From a functional point of view, brain damage is linked to acceleration-deceleration mechanisms (the most dangerous) responsible for stretching, crushing and shearing forces within the brain. These forces can stretch neurons (brain cells) and their axonal extensions (“cables”). Indeed, the brain weighing nearly 1400 grams has its own inertia, especially since it is not attached directly to the skull bone. During a sufficiently violent shock, the brain hits the Inside the skull behind and forward, or on the sides, like the human body subjected to a sudden acceleration or deceleration, type frontal accident in a car. The two mechanisms are often associated by a phenomenon of coup and contre-coup.
- Loss of initial knowledge
Equivalent to a knockout, a significant shaking of the brain will cause brain stunting, responsible for the loss of consciousness, and likely to trigger brain damage or hematoma. In general, the faster the return of consciousness, the greater the chances of a return to normal without squeal. On the other hand, a deep and lasting loss of consciousness is more worrying and may correspond to the existence of brain lesions. However, a quick return to normal is not enough to formally eliminate the existence of a brain injury. Consequently, any loss of initial knowledge in a traumatic context must be considered as a sign of seriousness, until proven otherwise, and lead to close clinical surveillance, and this, even in the absence of visible brain lesions on CT or MRI. But beware, the absence of initial loss of consciousness cannot be considered as the mark of a benign CT. Indeed, according to a large study, this initial loss of knowledge can be missing in 50 to 66% of cases where the CT scan finds an intracranial lesion.
- Skull fracture
The severity of a head injury does not depend solely on the existence or not of a fractured skull. Clearly, a radio graphically visible fracture should not be the only severity parameter for head trauma, which is why it is not routinely performed. Indeed, if the fracture of the skull is evidence of severe trauma, enough to break the bone, in itself it does not require any special treatment other than analgesics to calm the pain. We can therefore suffer from a skull fracture without any associated cerebral lesion or hematoma. One can also suffer from a serious intracranial hematoma, and this, in the absence of fracture of the skull. Some even consider that the fracture corresponds to the dissipation of the shock wave that goes to blur on the surface instead of spreading in the depth of the brain, thus protecting the underlying brain structures, like the shell of an egg. However, the finding of a fracture line, especially at the temporal level, should encourage caution because of an increased risk of developing an extra-Dural hematoma (risk multiplied by 25).
Several types of lesions
- The extra-cerebral hematomas
Located between the inner face of the skull and the surface of the brain, these extra-cerebral hematomas correspond to collections of blood most often linked to the tearing of the fine venous vessels irrigating the three membranes surrounding the brain (meanings) which are located just under the skull bone. Acceleration-deceleration phenomena can cause these pullouts. These three meanings constitute a cerebral protection are insufficient in case of major trauma.
In practice, there are:
- The so-called “subdural” hematomas, located between two meanings (the arachnoids and the durra, the outermost). Linked to venous tearing or the consequences of cerebral contusion, subdural hematoma can occur in the immediate aftermath of head trauma (coma from the outset) or more delayed. Surgery is essential in the majority of cases when there is a risk of compression of the brain. It consists of evacuating the hematoma.
- Extra-Dural hematoma, located between the inner side of the skull bone and the durra. Especially temporal, the extra-Dural hematomas are related to the existence of a lesion of the middle meningeal artery. Except for exception (extra-Dural hematoma of very small volume and well tolerated by the patient), this type of hematoma requires an emergency intervention (trepanation) to evacuate this collection of blood that also threatens to compress the brain.
- Intra-cerebral lesions
- They include several types of attacks, local or diffuse, which can associate and make the difficulty of the prognosis. Each head trauma is specific.
- Cranial trauma can therefore be accompanied in a fraction of a second by:
- Bruises on the surface of the brain. They correspond to injuries resulting from contact with the surface of the brain with the internal surface of the skull bone, despite the meanings. The bruises involve the front of the brain as the back (shock back) and the temporal area. Hematoma, necrosis of the site of bleeding, edema or small hemorrhages on the surface of the brain is possible.
- Neuronal lesions, or axonal lesions. Indeed, the two distinct layers constituting the brain and called white substances (in the center) and gray (covering the white substance on the outside), do not have the same density and therefore, a different inertia. During an impact, the separation zone of the two layers will be stretched or sheared, causing damage to the neurons that pass through it.
- Or delayed after several minutes or hours, by:
- Edema , which is an accumulation of water that will increase the pressure inside the brain around the lesion in the hours following the accident, with the risk of developing intracranial hypertension. And a repression of the mass of the brain on the opposite side (so-called “commitment syndrome”).
- Ischemia , much feared, in other words a decrease of oxygen in the brain tissue due to a decrease in vascularization, following the accident or the development of a compressive edema. A cascade of biochemical reactions can lead to cell death of the neurons concerned.
- Intracerebral haemorrhages (hematomas)
Diagnosis of head trauma
- Clinic . The diagnosis of head trauma can be obvious when it is reported by the conscious person concerned at the end of the loss of consciousness, or by the entourage, or suspected in an unconscious person in front of a wound, contusion or significant bruise of the leather scalp.
- Scanner . CT can be used to determine the lesional consequences of head trauma (fracture, haemorrhage, cerebral contusion, edema …). Warning, imaging can still be normal in some cases. Indeed, lesions can appear in the hours that follow and therefore not visible if the scanner is practiced early after the accident. In addition, some lesions, such as axonal fractures, are not detectable by conventional CT or MRI. Clearly, normal results of CT or MRI should not reassure 100% and monitoring of the clinical course of the person who has suffered head trauma is essential. Especially since there was an initial loss of consciousness or suspicious neurological symptoms.
- X-ray of the skull . It has no interest in the search for intracerebral lesions (intracerebral hematoma, bruises, ischemia, edema, commitment syndrome etc …) or extra-cerebral (extra-Dural or subdural hematomas) which can not to be highlighted by the simple X-rays delivered by radiography. Finding a fracture line on an X-ray of the skull after head trauma is not necessarily a sign of severity. As a result, a normal skull x-ray after head trauma does not warrant the absence of surveillance. Fracture of the skull or not, the monitoring is essential since the head trauma has been judged as severe, a fortiori if it was accompanied by
Every year 250 to 300 people / 100,000 are victims of a CT. 10% are considered severe.
People at risk for head trauma
- Alcoholic, chronic or acute intoxication and the use of drugs strongly expose to head trauma (falls, road accidents …).
- If everyone can be concerned one day or the other, young men between 15 and 30 years are the most frequently affected, especially by road accidents. Before age 5 and after age 70, head trauma occurs through a fall mechanism.
- At equal trauma, women appear more exposed in terms of squeal and speed of recovery.
- Taking anticoagulant (or aspirin) is an additional risk in case of head trauma (drop in the elderly in particular).
- The lack of protection (helmet) also exposes to head trauma (cyclists, motorcyclists, public works …)
- Babies, when shaken (shaken baby syndrome)
- The existence of a genetic susceptibility (presence of an unfavorable protein factor) that would slow down the recovery capacities.
Symptoms of head trauma
They depend on the intensity of the initial trauma and the injuries caused. Apart from pain and local lesions in the scalp (wound, hematoma, bruise …), head trauma can be accompanied by:
- From an initial loss of consciousness with a gradual return to consciousness. The duration of the loss of consciousness is important to know.
- From a coma right away , in other words, the absence of a return to consciousness after the initial loss of consciousness. This phenomenon is present in half of severe head trauma. It is attributed to axonal ruptures, ischemia or even edema occurring diffusely at the cerebral level. In addition to the persistent duration of coma and imaging data, the severity of head trauma is also estimated by using the so-called Glasgow Scale (Glasgow Test) to assess coma depth. .
- From a coma or a secondary loss of consciousness , that is to say that occurs at a distance from the accident. They correspond to the appearance of brain lesions. This is the case for extradural haematomas for example, which can occur up to 24 to 48 hours sometimes after head trauma because they are formed gradually.
- Of nausea and vomiting, which must urge caution as to return home in a conscious person after a shock on the skull? They require monitoring for several hours.
- Various neurological disorders: paralysis, aphasia, ocular mydriasis (excessive dilation of one pupil compared to the other)
Levels of severity and treatments of head trauma
Schematically, there are 3 different levels of severity:
– mild head trauma,
head trauma – severe head trauma.
All intermediaries are possible between the 3 degrees of gravity. Among the parameters used for the classification, we find the existence of an initial loss of consciousness, prolonged or not, of scalp lesions, associated neurological signs, epilepsy or an alteration of consciousness after head trauma. This classification, which remains relatively subjective, must make it possible to determine the course of action. In this sense, the clinical examination and the collection of the elements concerning the accident are essential.
Schematically, we distinguish three groups that condition the conduct to take:
- The traumatized cranial group 1 (light) . No neurological symptoms, headache, small vertigo, small scalp lesions, no sign of seriousness.
Conduct to keep: return home with surveillance by the entourage.
- Group 2 traumatic brain injury (moderate) . Initial loss of consciousness or disorders of consciousness since head trauma, progressive headaches, vomiting, polytrauma, fracture by facial trauma with effusion of cerebrospinal fluid in the nose, ears, intoxication (alcohol, drugs …), amnesia of the accident.
Conduct to be held: hospitalization for surveillance, CT and X-ray of the face if necessary.
- Group 3traumatic brain injury (severe) . Altered consciousness, neurological signs of localization of brain or extra-cerebral lesion, penetrating wound of the skull and / or depression.
Conduct to be maintained: hospitalization in a neurosurgical environment, CT scan.
Treatments of head trauma
It is not the head trauma that is treated, but its consequences. Every head trauma is special. Many treatments exist and can be associated, depending on the type of injury presented
- Surgical : evacuation of hematomas (drainage)
- Medical : fight against intracranial hypertension when the measurement of the pressure in the cranial box (intracranial pressure or ICP) requires it, oxygen therapy, put under artificial sleep, treatment against epileptic seizures, drugs to fight brain edema .
- And of course suture and cleansing scalp wounds