Trauma
Question 98 of 216
You are assessing a medical student as she examines a 32 year old man who has been assaulted. The medical student believes the patient has features suggestive of a basal skull fracture. Which of the following features is suggestive of a basal skull fracture?
Answer:
- Skull fractures can occur in the cranial vault or skull base. They may be linear or stellate as well as open or closed.
- Basal skull fractures usually require CT scanning with bone-window settings for identification.
- Clinical signs of a basilar skull fracture include:
- Periorbital ecchymosis (raccoon eyes)
- Retroauricular ecchymosis (Battle’s sign)
- CSF leakage from the nose (rhinorrhea) or ear (otorrhea)
- Dysfunction of cranial nerves VII and VIII (facial paralysis and hearing loss)
- Haemotympanum or bleeding from the ear
- Subconjunctival haemorrhage (with no posterior border seen)
- Some fractures traverse the carotid canals and can damage the carotid arteries (dissection, pseudoaneurysm, or thrombosis). In such cases, doctors should consider performing a cerebral arteriography (CT angiography [CT-A] or conventional angiogram).
- Open or compound skull fractures provide direct communication between the scalp laceration and the cerebral surface when the dura is torn.
- Do not underestimate the significance of a skull fracture, because it takes considerable force to fracture the skull. A linear vault fracture in conscious patients increases the likelihood of an intracranial haematoma by approximately 400 times.
Head Injury: Types of Injury
Trauma
Last Updated: 13th February 2021
Skull fractures
- Skull fractures can occur in the cranial vault or skull base. They may be linear or stellate as well as open or closed.
- Basal skull fractures usually require CT scanning with bone-window settings for identification.
- Clinical signs of a basilar skull fracture include:
- Periorbital ecchymosis (raccoon eyes)
- Retroauricular ecchymosis (Battle’s sign)
- CSF leakage from the nose (rhinorrhea) or ear (otorrhea)
- Dysfunction of cranial nerves VII and VIII (facial paralysis and hearing loss)
- Haemotympanum or bleeding from the ear
- Subconjunctival haemorrhage (with no posterior border seen)
- Some fractures traverse the carotid canals and can damage the carotid arteries (dissection, pseudoaneurysm, or thrombosis). In such cases, doctors should consider performing a cerebral arteriography (CT angiography [CT-A] or conventional angiogram).
- Open or compound skull fractures provide direct communication between the scalp laceration and the cerebral surface when the dura is torn.
- Do not underestimate the significance of a skull fracture, because it takes considerable force to fracture the skull. A linear vault fracture in conscious patients increases the likelihood of an intracranial haematoma by approximately 400 times.
Diffuse intracranial injuries
- Diffuse brain injuries range from mild concussions, in which the head CT is normal, to severe hypoxic, ischaemic injuries.
- With a concussion, the patient has a transient, nonfocal neurological disturbance that often includes loss of consciousness.
- Severe diffuse injuries often result from a hypoxic, ischaemic insult to the brain from prolonged shock or apnoea occurring immediately after the trauma.
- In such cases, the CT may initially appear normal, or the brain may appear diffusely swollen, and the normal gray-white distinction is absent.
- Another diffuse pattern, often seen in high-velocity impact or deceleration injuries, may produce multiple punctate haemorrhages throughout the cerebral hemispheres.
- These “shearing injuries,” often seen in the border between the gray matter and white matter, are referred to as diffuse axonal injury (DAI) and define a clinical syndrome of severe brain injury with variable but often poor outcome.
Focal intracranial injuries
Focal lesions include epidural haematomas, subdural haematomas, contusions, and intracerebral haematomas.
- Epidural (extradural) haematomas
- An epidural haematoma is a collection of blood in the potential space (epidural space) between the dura and the skull.
- Epidural haematomas are relatively uncommon, occurring in about 0.5% of patients with brain injuries and 9% of patients with TBI who are comatose.
- These haematomas typically become biconvex or lenticular in shape as they push the adherent dura away from the inner table of the skull.
- They are most often located in the temporal or temporoparietal regions and often result from a tear of the middle meningeal artery due to fracture.
- These clots are classically arterial in origin; however, they also may result from disruption of a major venous sinus or bleeding from a skull fracture.
- The classic presentation of an epidural haematoma is with a lucid interval between the time of injury and neurological deterioration.
- Subdural haematomas
- A subdural haematoma is a collection of blood in the potential space (subdural space) between the dura mater and the arachnoid mater.
- Subdural haematomas are more common than epidural haematomas, occurring in approximately 30% of patients with severe brain injuries.
- They often develop from the shearing of small surface or bridging blood vessels of the cerebral cortex; cerebral atrophy occurs in older people and in chronic alcohol misuse, causing tension on the veins which are consequently more susceptible to injury.
- In contrast to the lenticular shape of an epidural haematoma on a CT scan, subdural haematomas often appear to conform to contours of the brain.
- Damage underlying an acute subdural haematoma is typically much more severe than that associated with epidural haematomas due to the presence of concomitant parenchymal injury.
- Contusions and intracerebral haematomas
- Cerebral contusions are fairly common; they occur in approximately 20% to 30% of patients with severe brain injuries.
- Most contusions are in the frontal and temporal lobes, although they may be in any part of the brain.
- In a period of hours or days, contusions can evolve to form an intracerebral haematoma or a coalescent contusion with enough mass effect to require immediate surgical evacuation. This condition occurs in as many as 20% of patients presenting with contusions on initial CT scan of the head. For this reason, patients with contusions generally undergo repeat CT scanning to evaluate for changes in the pattern of injury within 24 hours of the initial scan.
Secondary brain injury
- The aim in the management of patients with major head injuries is generally to prevent secondary brain injury.
- Whereas primary brain injury (focal and diffuse) results from mechanical injury at the time of the trauma, secondary brain injury is caused by the physiologic responses to the initial injury.
- Secondary injury occurs in the hours to weeks following a primary injury, and is caused by many different structural and chemical changes that lead to further destruction of brain tissue.
- The most important contributors to secondary brain injury are cerebral oedema, expanding haematoma, hypoxia and hypotension.
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- Biochemistry
- Blood Gases
- Haematology
| Biochemistry | Normal Value |
|---|---|
| Sodium | 135 – 145 mmol/l |
| Potassium | 3.0 – 4.5 mmol/l |
| Urea | 2.5 – 7.5 mmol/l |
| Glucose | 3.5 – 5.0 mmol/l |
| Creatinine | 35 – 135 μmol/l |
| Alanine Aminotransferase (ALT) | 5 – 35 U/l |
| Gamma-glutamyl Transferase (GGT) | < 65 U/l |
| Alkaline Phosphatase (ALP) | 30 – 135 U/l |
| Aspartate Aminotransferase (AST) | < 40 U/l |
| Total Protein | 60 – 80 g/l |
| Albumin | 35 – 50 g/l |
| Globulin | 2.4 – 3.5 g/dl |
| Amylase | < 70 U/l |
| Total Bilirubin | 3 – 17 μmol/l |
| Calcium | 2.1 – 2.5 mmol/l |
| Chloride | 95 – 105 mmol/l |
| Phosphate | 0.8 – 1.4 mmol/l |
| Haematology | Normal Value |
|---|---|
| Haemoglobin | 11.5 – 16.6 g/dl |
| White Blood Cells | 4.0 – 11.0 x 109/l |
| Platelets | 150 – 450 x 109/l |
| MCV | 80 – 96 fl |
| MCHC | 32 – 36 g/dl |
| Neutrophils | 2.0 – 7.5 x 109/l |
| Lymphocytes | 1.5 – 4.0 x 109/l |
| Monocytes | 0.3 – 1.0 x 109/l |
| Eosinophils | 0.1 – 0.5 x 109/l |
| Basophils | < 0.2 x 109/l |
| Reticulocytes | < 2% |
| Haematocrit | 0.35 – 0.49 |
| Red Cell Distribution Width | 11 – 15% |
| Blood Gases | Normal Value |
|---|---|
| pH | 7.35 – 7.45 |
| pO2 | 11 – 14 kPa |
| pCO2 | 4.5 – 6.0 kPa |
| Base Excess | -2 – +2 mmol/l |
| Bicarbonate | 24 – 30 mmol/l |
| Lactate | < 2 mmol/l |
