Epidural Hemorrhage (EDH), also known as an epidural hematoma, represents a critical and potentially devastating form of traumatic brain injury (TBI). It is characterized by the accumulation of blood in the potential space between the inner surface of the skull and the outermost layer of the brain's covering, the dura mater. This condition demands immediate recognition and neurosurgical intervention to prevent catastrophic neurological deficits or death. Understanding the pathophysiology, clinical presentation, and characteristic imaging features is paramount for all clinicians, particularly those managing acute trauma.
Pathophysiology of Epidural Hemorrhage
The primary mechanism leading
to EDH is a severe head injury, typically involving a skull fracture.
The force of the trauma often causes a tear in the underlying vascular
structures, most commonly the middle meningeal artery (MMA) or one of
its branches, which traverses the temporal bone. While venous sources, such as
dural sinuses, can also be implicated, arterial bleeding from the MMA is
responsible for the majority of EDH cases, accounting for the rapid
accumulation and life-threatening nature of the hematoma.
As arterial blood rapidly
collects, it dissects the dura mater from the inner table of the skull, leading
to the classic biconvex (lenticular or lens-shaped) hematoma. The dura
mater is tightly adhered to the skull at the cranial sutures, which is why the
hematoma typically does not cross suture lines—a key diagnostic feature
on imaging.
The rapidly expanding hematoma
creates a mass effect, progressively increasing the intracranial pressure
(ICP). As ICP rises, it can lead to herniation of brain tissue
(e.g., transtentorial herniation), causing compression of vital brainstem
structures (like the oculomotor nerve, leading to ipsilateral fixed and dilated
pupil) and, ultimately, brainstem failure and death if not urgently managed.
Epidemiology: Who is at Risk?
While EDH is relatively
uncommon, accounting for approximately 1-3% of all head injuries, it is
disproportionately represented in certain demographics:
- Age: EDH
is most frequent in young adults and adolescents, particularly
those in their second and third decades of life (the 10-30 age range). The
higher incidence in this group is often attributed to the greater
elasticity and adherence of the dura mater in younger individuals, requiring
more force to separate the dura from the bone, which in turn increases the
likelihood of a major vessel tear like the MMA. The middle-aged and
elderly tend to have more adherent dural attachments, making subdural
hematoma (SDH) more common.
- Sex: Males
are affected more frequently than females, largely reflecting a higher
incidence of high-impact trauma in this group.
- Mechanism: The vast majority of cases (75-95%) are associated with a linear
skull fracture that crosses the path of the MMA. Common etiologies
include motor vehicle accidents, assaults (as seen in the presented case),
and falls.
Clinical Presentation: The Classic Lucid Interval
The clinical presentation of
EDH is highly variable and can evolve rapidly, but the classic finding is the "lucid
interval".
- Initial Loss of Consciousness (LOC): The patient may momentarily lose consciousness
immediately following the impact.
- Lucid Interval: Following the brief LOC, the patient may awaken and appear
relatively normal (the lucid interval). This period can last minutes to
hours. The case study describes a patient who initially lost consciousness
for 5 minutes after being struck with a glass bottle but was later
discharged, only to return with worsening symptoms two hours later.
- Rapid Deterioration: As the arterial hematoma rapidly expands,
increasing the ICP, the patient's condition rapidly worsens. Symptoms
include:
- Severe Headache
- Nausea and Vomiting
- Decreasing Level of Consciousness (LOC): Progressing from confusion to stupor, and
finally coma. While the patient in the case study was initially GCS 15,
this is a crucial symptom of progression.
- Focal Neurological Deficits: Often hemiparesis (weakness on one side
of the body) contralateral to the hematoma.
- Pupillary Changes: The classic sign of tentorial herniation is an ipsilateral,
fixed, and dilated pupil due to compression of the third cranial
nerve (oculomotor nerve).
Imaging Features: Computed Tomography (CT) Scan
Computed
Tomography (CT) remains
the gold standard for the rapid diagnosis of acute EDH. The key features are
critical for distinguishing EDH from other forms of intracranial hemorrhage:
1. The Classic Lenticular Shape (Biconvex)
- The
hematoma appears as a hyperdense (white/bright) collection,
indicating acute blood, that is shaped like a biconvex lens (or a
lemon).
- This
shape is due to the arterial pressure stripping the dura from the skull,
but the tight adherence of the dura to the sutures restricts the spread,
causing the collection to bulge inward.
2. Does Not Cross Suture Lines
- A
definitive feature: the collection is restricted by the cranial sutures.
This helps differentiate EDH from a Subdural Hemorrhage (SDH), which often
crosses suture lines but respects the falx cerebri and tentorium.
3. Associated Skull Fracture
- A skull
fracture is present in a high percentage of cases (up to 90%).
High-resolution bone window CT is essential for visualizing the fracture.
4. Mass Effect
- Large
hematomas will cause significant mass effect, visible as effacement
of the cortical sulci, compression of the ventricles, and midline
shift of the brain tissue (as seen in the attached images). The red
arrow in [Figure 1] points to the midline shift.
Case Study Imaging Analysis
The provided CT images clearly
demonstrate the diagnostic features of EDH:
[Figure 1] Axial brain window: Shows a large, hyperdense (acute blood), lenticular-shaped
mass in the left temporoparietal region. Note the significant midline
shift to the right, indicated by the red arrow. This shift is an indicator
of dangerously high ICP.
[Figure 2] Coronal brain window: Confirms the large, peripherally located, biconvex hematoma, characteristic of EDH.
[Figure 3] Axial bone window: Confirms the large, biconvex shape of the left Epidural
Hemorrhage and its peripheral location, abutting the inner table of the
skull.
[Figure 4] Axial brain window: An additional axial view confirming the extensive left-sided Epidural Hemorrhage and significant mass effect.
Differential Diagnosis: Distinguishing Intracranial
Hemorrhages
The primary goal of the trauma
physician is to distinguish EDH from other life-threatening intracranial
hemorrhages.
|
Condition |
Location |
Classic
Shape |
Suture
Line Crossing |
Typical
Mechanism |
|
Epidural
Hemorrhage (EDH) |
Between
skull and dura |
Biconvex
(Lens-shaped) |
Does NOT
cross sutures |
Skull
fracture, Arterial (MMA) tear |
|
Subdural
Hematoma (SDH) |
Between
dura and arachnoid |
Crescent-shaped (Concave-convex) |
Crosses
sutures (but respects the falx) |
Tearing
of bridging veins (often in elderly/alcoholics) |
|
Subarachnoid
Hemorrhage (SAH) |
Between
arachnoid and pia |
Fills
cisterns and sulci |
Follows
brain contours |
Aneurysm
rupture (Traumatic SAH is also common) |
|
Intraparenchymal
Hemorrhage (ICH) |
Within
brain parenchyma |
Irregular,
within the brain tissue |
N/A |
Trauma,
uncontrolled hypertension, AVM |
Diagnosis and Treatment: The Race Against Time
Diagnosis
Diagnosis relies on a
combination of clinical findings (history of trauma, LOC, the lucid
interval, neurological deterioration) and rapid imaging. CT scan is the
cornerstone, providing immediate confirmation of the hematoma and its size,
location, and associated mass effect.
Treatment
EDH is a neurosurgical
emergency. The goal is rapid decompression to relieve the mass effect and
lower the ICP.
- Non-Surgical Management: Very small, stable EDHs (often < 30 ml volume, 15
mm thickness, GCS >= 8, no focal deficit) may be managed conservatively
in a neuro-ICU with close neurological monitoring and ICP control.
- Surgical Evacuation: The definitive treatment for symptomatic or large
EDHs is urgent burr hole placement and/or craniotomy for hematoma
evacuation. This is often the first procedure in emergency settings to
save the patient's life. The bleeding vessel (usually the MMA) is identified
and cauterized or ligated to prevent re-bleeding.
Key
Principle: Time is Brain.
Immediate intervention is crucial to prevent further secondary brain injury and
potentially fatal complications.
Prognosis and Prevention
Prognosis
The prognosis for EDH is
directly tied to the speed of diagnosis and surgical intervention.
- Patients
who undergo surgery while conscious (GCS 13-15) often have an excellent
prognosis, with a high chance of complete recovery.
- Delay
in treatment, progression to coma (GCS $\le 8$), or significant associated
brain injury leads to a much poorer outcome, including severe disability
or death.
- Other
factors include the size and location of the hematoma and the patient's
age.
Prevention
Prevention primarily revolves
around reducing head trauma. This includes:
- Protective Equipment: Mandating and using helmets in high-risk activities
(sports, cycling, construction).
- Safety Measures: Promoting seatbelt use and enforcing driving safety laws.
- Public Awareness: Educating the public and clinicians on the importance of immediate medical evaluation after any head injury, even if symptoms appear minor (recognizing the dangers of the lucid interval).
Quiz
Question 1: (Pathophysiology and Vascular Source) A 25-year-old male presents with a brief loss of
consciousness after a blunt head trauma, followed by a "lucid
interval." His neurological status then rapidly deteriorates. A CT scan
confirms an Epidural Hemorrhage. What is the most common vascular structure
injured in a typical EDH, and what anatomical finding on a non-contrast CT scan
differentiates it from a Subdural Hematoma?
(A) Anterior cerebral artery; It is crescent-shaped
and crosses suture lines.
(B) Superior sagittal sinus; It is biconvex and
crosses the midline falx cerebri.
(C) Middle meningeal artery; It is biconvex
(lenticular) and does NOT cross suture lines.
(D) Bridging veins; It is biconvex and is usually only
seen in the elderly.
(E) Posterior cerebral artery; It is crescent-shaped
and does NOT cross the tentorium.
Answer
& Explanation
Answer: (C)
Explanation: The vast majority of EDHs are caused by a tear in the
Middle Meningeal Artery (MMA), often in association with a skull
fracture. The arterial pressure causes the blood to rapidly strip the dura
mater from the skull, creating a biconvex (lens-shaped) collection. Crucially,
the tight adherence of the dura to the cranial sutures prevents the hematoma
from crossing these lines, a feature that distinguishes it from the
crescent-shaped Subdural Hematoma (SDH).
Question 2: (Clinical Presentation and The Lucid
Interval) The 18-year-old patient in the
case study was initially struck and lost consciousness for 5 minutes. He was
later discharged, only to return 2 hours later with severe headache, nausea,
and vomiting. This clinical course is classic for Epidural Hemorrhage. What is
the most critical physiological reason for the rapid, severe deterioration
following the lucid interval?
(A) Tearing of the subdural bridging veins, leading to
a slow, chronic increase in blood volume.
(B) Venous bleeding from the superior sagittal sinus
causing cerebral edema.
(C) Auto-regulation failure of cerebral blood flow due
to an ischemic stroke.
(D) Rapid accumulation of arterial blood, creating
a critical mass effect and leading to rapidly increasing Intracranial Pressure
(ICP).
(E) A delayed inflammatory reaction to the traumatic
impact.
Answer
& Explanation
Answer: (D)
Explanation: EDH is typically an arterial bleed (MMA). Arterial
pressure is high, causing blood to accumulate rapidly. This rapid
accumulation within the fixed volume of the skull creates a quickly expanding
mass effect, leading to a catastrophic rise in Intracranial Pressure (ICP).
The lucid interval ends abruptly when the ICP reaches a critical threshold,
leading to brainstem compression and subsequent neurological decline.
Question 3: (Management and Prognosis) A patient is diagnosed with a large, symptomatic
Epidural Hemorrhage with evidence of significant midline shift on CT (similar
to Figure 1). What is the immediate, life-saving definitive management for this
patient, and what factor most positively affects their long-term outcome?
(A) Administration of IV mannitol and close monitoring
in a general ward.
(B) Emergency intubation and continuous
hyperventilation to maintain pCO2 below 20 mmHg.
(C) Initiation of therapeutic hypothermia and
anti-seizure medication.
(D) Urgent surgical evacuation via craniotomy; the
best prognosis is achieved if the surgery is performed while the patient is
still conscious (high GCS).
(E) Lumbar puncture to relieve pressure and
antibiotics to prevent infection.
Answer
& Explanation
Answer: (D)
Explanation: Large, symptomatic EDHs are a neurosurgical emergency
requiring urgent surgical evacuation (craniotomy or burr holes) to
remove the hematoma and decompress the brain. Prognosis is highly dependent on
the patient's neurological status at the time of surgery; patients who are
operated on while conscious (GCS >= 13) have a significantly better
prognosis than those operated on in a comatose state.
References
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M. R., Chesnut, R., Ghajar, J., Gordon, D., Hartl, R., Newell, D. W., et
al. (2006). Guidelines for the management of severe traumatic brain
injury. Journal of Neurotrauma, 23(Suppl 1), S1-S86.
- Greenberg,
M. S. (2020). Handbook of Neurosurgery (9th ed.). Thieme.
- Servadei,
F., Compagnone, C., & Esente, S. (2018). Traumatic Extradural
Hematoma: Management and Surgical Treatment. Acta Neurochirurgica, 160(8),
1693–1697.
- Gennarelli,
T. A., & Graham, D. I. (2005). Neuropathology of Head Trauma.
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- Ko, T.
I., Park, Y. S., Park, S. S., Lim, B. J., Kim, K. B., Kim, K. H., et al.
(2022). Epidural Hematoma in Traumatic Brain Injury. Journal of Korean
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J. S., & Shiozawa, P. (2023). Epidural Hematoma. StatPearls
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