CT Interpretation: Head

The emergency physician should be adept at the interpretation of computed tomography of the head, particularly for life-threatening processes where awaiting a radiologist interpretation may unnecessarily delay care.

As with the approach detailed previously for imaging of the abdomen and pelvis, a similar structured method for interpretation of head imaging exists and follows the mnemonic “Blood Can Be Very Bad”.

Normal Neuroanatomy

Brainstem
Posterior Fossa
High Pons
Cisterns
Ventricles

Blood: Blood

Density
Acute: hyperdense (50-100HU)
1-2wks: isodense with brain
2-3wks: hypodense with brain

Types/Locations

Intraparenchymal Hemorrhage/Contusions
Sudden deceleration of the head causes the brain to impact on bony prominences (e.g., temporal, frontal, occipital poles).
Non-traumatic hemorrhagic lesions seen more frequently in elderly and located in basal ganglia.
Intraventricular Hemorrhage
White density in otherwise black ventricular spaces, can lead to obstructive hydrocephalus and elevated ICP.
Associated with worse prognosis in trauma.
Subarachnoid Hemorrhage
Hemorrhage into subarachnoid space usually filled with CSF (cistern, brain convexity).
Extracranial Hemorrhage
Presence of significant extracranial blood or soft-tissue swelling should point examiner to evaluation of underlying brain parenchyma, opposing brain parenchyma (for contrecoup injuries) and underlying bone for identification of fractures.

Can: Cisterns


Evaluating the cisterns is important for the identification of increased intracranial pressures (assessed by effacement of spaces) and presence of subarachnoid blood.

  • Circummesencephalic: CSF ring around midbrain and most sensitive marker for elevated ICP
  • Suprasellar: Star-shaped space above the sella
  • Quadrigeminal: W-shaped space at the top of the midbrain
  • Sylvian: Bilateral space between temporal/frontal lobes

Be: Brain

Evaluate the brain parenchyma, including an assessment of symmetry of the gyri/sulci pattern, midline shift, and a clear gray-white differentiation.

Very: Ventricles

Evaluate the ventricles for dilation or compression. Compare the ventricle size to the size of cisterns, large ventricles with normal/compressed cisterns and sulcal spaces suggests obstruction.

Bad: Bone

Switch to bone windows to evaluate for fracture. The identification of small, linear, non-depressed skull fractures may be difficult to identify as they are often confused with sutures – surrogates include pneumocephalus, and abnormal aeration of mastoid air cells and sinuses. The Presence of fractures increases the suspicion for intracranial injury, search adjacent and opposing parenchyma and extra-axial spaces.

Example #1

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CT Head Interpretation

  • Ill-defined lesion in right parietal white matter with a large amount of surrounding vasogenic edema with midline shift and right uncal herniation.
  • Acute on subacute right extra-axial subdural hematoma.
  • Effacement of basilar cisterns.

Example #2

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CT Head Interpretation

  • Bilateral subacute subdural hematomas, left larger than right and associated with rightward midline shift.
  • Left lateral ventricle is partially effaced.

Example #3

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CT Head Interpretation

Subdural hematoma with significant herniation

References

  1. Perron A. How to read a head CT scan. Emergency Medicine. 2008.
  2. Arhami Dolatabadi A, Baratloo A, Rouhipour A, et al. Interpretation of Computed Tomography of the Head: Emergency Physicians versus Radiologists. Trauma Mon. 2013;18(2):86–89. doi:10.5812/traumamon.12023.

Pediatric Head Trauma

Brief H&P:

A young child, otherwise healthy, is brought to the pediatric emergency department after a fall. The parents report a fall from approximately 2 feet after which the patient cried immediately and without apparent loss of consciousness. Over the course of the day, the patient developed an enlarging area of swelling over the left head. The parents were concerned about a progressive decrease in activity and interest in oral intake by the child, and they were brought to the emergency department for evaluation. Examination demonstrated a well-appearing and interactive child – appropriate for age. Head examination was notable for a 5x5cm hematoma over the left temporoparietal skull with an underlying palpable skull irregularity not present on the contralateral side. Non-contrast head computed tomography was obtained.

Imaging

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CT Head

Fracture of the left temporal and parietal bone with overlying scalp hematoma.

Algorithm for the Evaluation of Pediatric Head Trauma (PECARN)1,2,3

Algorithm for the evaluation of pediatric head trauma

References

  1. Kuppermann N, Holmes JF, Dayan PS, et al. Identification of children at very low risk of clinically-important brain injuries after head trauma: a prospective cohort study. Lancet. 2009;374(9696):1160-1170. doi:10.1016/S0140-6736(09)61558-0.
  2. Brenner D, Elliston C, Hall E, Berdon W. Estimated risks of radiation-induced fatal cancer from pediatric CT. American Journal of Roentgenology. 2001;176(2):289-296. doi:10.2214/ajr.176.2.1760289.
  3. Schonfeld D, Bressan S, Da Dalt L, Henien MN, Winnett JA, Nigrovic LE. Pediatric Emergency Care Applied Research Network head injury clinical prediction rules are reliable in practice. Archives of Disease in Childhood. 2014;99(5):427-431. doi:10.1136/archdischild-2013-305004.

Spontaneous Intracranial Hemorrhage

Brief HPI

An approximately 40 year-old male with a history of aortic stenosis s/p mechanical aortic valve replacement (on Coumadin) as well as hypertension presented to the emergency department with a chief complaint of severe headache. The patient was in severe distress on arrival and was unable to provide detailed history, he complained of two days of severe left-sided headache while clutching his head and groaning. Examination was notable for sensory localization with directed movements of right hemibody, and no apparent response on the left. He was taken to emergently for CT head non-contrast.

Imaging

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CT Head non-contrast

57 mm right posterior parenchymal hemorrhage with intraventricular component. Moderate edema, mass effect and 9 mm of midline shift.

ED Course

Admission INR was 2.9, the patient received 25 units/kg of PCC as well as vitamin K 10mg IV x1. Neurosurgery was consulted and the patient was taken to the operating room for management.

Management of Supratherapeutic INR and Complications of Anti-Coagulation

Management of Supratherapeutic INR

References

  1. Ansell J, Hirsh J, Hylek E, et al. Pharmacology and management of the vitamin K antagonists: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines (8th Edition). Chest 2008; (6 Suppl):160s

Severe Traumatic Brain Injury

HPI:

34 year-old male brought in by ambulance s/p assault. Field GCS reportedly 7, in trauma bay assessed as E2-V4-M6. Witnessed seizure in CT scanner, resolved with lorazepam. Intubated for airway protection, underwent external ventricular drain placement and transferred to surgical ICU.

Initial imaging revealed bifrontal subdural hematomas and right temporal hemorrhagic contusion with generalized edema. Repeat imaging one hour later showed interval development of large extra-axial hemorrhage overlying the right occipital and parietal lobes (2.2cm), representing subdural or epidural hematoma.

The patient’s ICU course was complicated by continued seizures and refractory elevation in intracranial pressure. A pentobarbital infusion was started and titrated to adequate burst suppression and hyperosmolar therapy with both mannitol and hypertonic saline continued. Additional imaging revealed stable hemorrhage but continued diffuse cerebral edema evidenced by sulcal effacement.

On hospital day 5, examination revealed bilateral fixed and dilated pupils. Imaging revealed effacement of basilar cisterns, pre-pontine cistern, and cisterna magna suggestive of impending/ongoing transtentorial and tonsillar herniation. Pentobarbital was weaned and conventional cerebral angiography as well as cerebral perfusion studies were consistent with brain death.

Images

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CT head without contrast one hour after presentation

  • Large extra-axial posterior hemorrhages. Hemorrhagic contusions in the right frontal and temporal lobes.
  • The cerebral sulci appear effaced – findings suggest diffuse cerebral edema.
  • S/p EVD using a right frontal approach.
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CT head without contrast on hospital day 5

  • Interval evidence of global hypoxic/ischemic injury to the brain.
  • Interval apparent effacement of the basilar cisterns, pre-pontine cistern, and cisterna magna suggesting impending/ongoing downward transtentorial herniation and tonsillar herniation.
  • Stable supra/infratentorial subdural/epidural hematoma.

Algorithm for the Management of Severe Traumatic Brain Injury1,2

Algorithm for the Management of Severe Traumatic Brain Injury

References

  1. Brain Trauma Foundation, American Association of Neurological Surgeons, Congress of Neurological Surgeons, Joint Section on Neurotrauma and Critical Care, AANS/CNS, Carney, N. A., & Ghajar, J. (2007). Guidelines for the management of severe traumatic brain injury. Introduction. Journal of neurotrauma, 24 Suppl 1, S1–2. doi:10.1089/neu.2007.9997
  2. Stocchetti, N., & Maas, A. I. R. (2014). Traumatic intracranial hypertension. The New England journal of medicine, 370(22), 2121–2130. doi:10.1056/NEJMra1208708
  3. WikEM: Severe traumatic brain injury

Head Trauma: Radiographic Evolution

CT Head (Initial)

CT Head (Initial)

- Noncontrast axial images through the head demonstrate no evidence of skull fracture.
- Large lentiform-shaped mixed density extra-axial acute epidural hematoma in the right parietal occipital
- Associated subdural hematoma tracking along right convexity toward the right temporal lobe.
- There is no evidence of midline shift.

CT Head (+8h)

CT Head (+8h)

- Significant interval increase in the size of the right hemispheric subdural hematoma
- There is now midline shift from right to left at the level of the septum pellucidum measuring 10 mm, partial effacement of the right lateral ventricle and subfalcial herniation.
- Scattered subarachnoid blood is redemonstrated.
- Comminuted fractures of the nasal bone are present and there is overlying and associated periorbital soft tissue swelling.

CT Head (+16h, s/p SDH evacuation)

CT Head (+16h, s/p SDH evacuation)

- Interval gross total evacuation of right hemispheric subdural hematoma.
- Moderate anterior bifrontal subdural and right epidural air is present.
- Small scattered subarachnoid and intraventricular blood is redemonstrated.

Skull Fracture

Frontal bone fractureID:

14 year-old female, previously healthy, brought in by ambulance s/p auto vs. pedestrian.

HPI:

Incident unwitnessed, paramedics report no LOC with GCS 15 at scene. GCS 10 upon arrival to ED, with 2min GTC seizure. Patient intubated for airway protection and CT head showed non-displaced frontal bone fracture and small frontal SAH. Patient self-extubated, returned to baseline mental status and was transferred to PICU.

PE:

  • VS: 128/76mmHg, 120bpm, 22 R/min, 100% RA, 37.6°C
  • General: Alert and responsive young female with multiple bandages on extremities
  • HEENT: Right frontal hematoma, no bony defect palpated, multiple facial abrasions, no otorrhea, no rhinorrhea, TM clear b/l, no other ecchymosis.
  • CV: RRR, normal S1/S2, no M/R/G
  • Lungs: CTAB
  • Abdomen: +BS, soft, NT/ND, no rebound/guarding, no flank ecchymoses
  • Neuro: AAOx3, CN II-XII intact, sensation/motor/reflexes symmetric and intact.
  • Extremities: Well-perfused with good pulses, no focal bony tenderness, no joint effusions, multiple abrasions on extensor surfaces of all four extremities.

Assessment & Plan:

14yo female, previously healthy, s/p auto vs. peds followed by GTC seizure and CT head showing small SAH and non-displaced frontal bone skull fracture. No evidence of basilar skull fracture on examination or imaging. Seizure likely 2/2 irritation from SAH. Patient was followed closely in PICU with q1h neuro checks with low threshold for repeat CT if change in mental status or more seizures occurred. The patient was eventually transferred to the general ward and was discharged with neurology follow-up and Keppra for seizure prophylaxis for 6mo.

Types of Skull Fractures:

A system for skull fractures