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1. How are head injuries generally classified?
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Correct answer:
Injuries are usefully classified according to the structures involved (scalp, skull and underlying brain) together with the mechanism of the injury, be it penetrating or blunt, and whether an acceleration/deceleration and/or a rotational brain injury occurred.
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2. What is the significance of a scalp injury?
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Correct answer:
Most scalp injuries are simple penetrating injuries, which are readily managed by debridement and suture. When the skull is also penetrated, the brain may be lacerated. However, if the injury occurred when the head was stationary, in the absence of acceleration and deceleration, consciousness may not be lost and neither the patient nor the doctor may appreciate the true extent of the injury.
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3. What are the general classifications of the type of head injury?
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Correct answer:
Injuries are usefully classified according to the structures involved (scalp, skull and underlying brain) together with the mechanism of the injury, be it penetrating or blunt, and whether an acceleration/deceleration and/or a rotational brain injury occurred. In reality, isolated injuries are uncommon, and patients more typically experience blunt injury fracturing the skull in which deceleration/acceleration of the brain also occurs.
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4. What are the clinical features of fractures involving the paranasal air sinuses?
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Correct answer:
Fractures extending through any of the paranasal air sinuses (frontal, ethmoidal or sphenoid) communicate with the outside and are therefore compound (open) fractures, as the overlying dura is usually breached. This external communication may manifest as a runny nose, the clear cerebrospinal fluid (CSF) being rich in glucose and low in mucin content (and positive for tau protein), compared with the normal nasal secretion, which contains no sugar and is rich in mucin. Such a connection may also be indicated by intracranial air (aerocele), or fluid in one of the sinuses on computed tomography scan or skull X-ray. Anosmia may occur if the fracture crosses the cribriform plate. Such patients are at risk of meningitis. Some CSF leaks heal spontaneously, particularly those involving the temporal lobe, but a persistent leak will require dural repair.
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5. What is the difference between the composition of cerebrospinal fluid and normal nasal secretion?
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Correct answer:
The cerebrospinal fluid is rich in glucose and low in mucin content (and positive for tau protein), compared with the normal nasal secretion, which contains no sugar and is rich in mucin.
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6. What specific type of protein is found in cerebrospinal fluid?
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Correct answer:
Tau protein.
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7. What are the physical signs of a fracture of the anterior fossa of the skull?
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Correct answer:
(1) Nasal bleeding. (2) Orbital haematoma. (3) Cerebrospinal fluid rhinorrhoea. (4) Cranial nerve injuries – nerves I to VI.
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8. What are the physical signs of a fracture of the middle fossa of the skull?
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Correct answer:
(1) Orbital haematoma. (2) Bleeding from the ear. (3) Cerebrospinal fluid otorrhoea (rare). (4) Cranial nerve injuries – nerves VII and VIII.
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9. What are the physical signs of a fracture of the posterior fossa of the skull?
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Correct answer:
(1) Bruising over the suboccipital region, which develops after a day or two (Battle’s sign). (2) Cranial nerve injuries – IX, X and XI (rare).
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10. What is Battle’s sign?
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Correct answer:
This is bruising over the suboccipital region; it develops a day or two after injury and indicates a skull fracture of the posterior fossa.
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11. What are the causes of coma?
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Correct answer:
(1) Central nervous system: trauma and disease (e.g. cerebrovascular accident (commonest), epilepsy, subarachnoid haemorrhage, cerebral tumour, abscess and meningitis) (2) Drugs: alcohol, carbon monoxide, barbiturates, aspirin and opiates. (3) Diabetes: hyperglycaemia and hypoglycaemia. (4) Uraemia. (5) Hepatic failure. (6) Hypertensive encephalopathy. (7) Profound toxaemia. (8) Hysteria. It is usually easy enough to determine that unconsciousness is due to trauma, but it is important to remember that a drunk or epileptic person, for example, may have struck his or her head in falling so that the condition is complicated by a head injury.
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12. What are the characteristics of fractures of the petrous temporal bone?
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Correct answer:
Fractures through the petrous temporal bone may result in cerebrospinal fluid (CSF) otorrhoea, as CSF passes through into the external auditory meatus, either directly or via the mastoid air cells or middle ear in the presence of a ruptured tympanic membrane. If the tympanic membrane is intact, CSF rhinorrhoea occurs via the Eustachian tube. Involvement of the inner ear will result in deafness. Spontaneous resolution of the leak is usual.
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13. What are the characteristics of fractures through the temporal bone?
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Correct answer:
A fracture through the temporal bone may disrupt the middle meningeal artery and/or vein as they traverse the bone and result in an extradural haemorrhage, which may not manifest immediately.
