Saturday, March 13, 2021

Epidural Hematoma Case File

Posted By: Medical Group - 3/13/2021 Post Author : Medical Group Post Date : Saturday, March 13, 2021 Post Time : 3/13/2021
Epidural Hematoma Case File
Eugene C. Toy, MD, Lawrence M. Ross, MD, PhD, Han Zhang, MD, Cristo Papasakelariou, MD, FACOG

CASE 44
A 15-year-old boy was the pitcher for his little league baseball team when he was hit by a line drive to the right temple area. He lost consciousness briefly but woke up after about 45 s and had no neurological deficits. He was taken to the emergency room and seemed to be in good condition. Four hours later, while being observed, he complained of an increasing headache and had a seizure. On examination, the patient’s right pupil appeared dilated and reacted sluggishly to light. The emergency physician is concerned about increased intracranial pressure.

 What is the most likely diagnosis?
 What is the anatomical explanation for this condition?


ANSWER TO CASE 44:

Epidural Hematoma
Summary: A 15-year-old boy was hit by a baseball to the right temple area. He lost consciousness briefly and had a lucid interval. Four hours later, he developed an increasing headache, a dilated and sluggish right pupil, and had a seizure, consistent with increased intracranial pressure.

• Most likely diagnosis: Epidural hematoma resulting in increased intracranial pressure

• Anatomical explanation for this condition: Disruption of a branch of the middle meningeal artery, which causes a growing hematoma between the dura and cranium and puts pressure on the underlying brain


CLINICAL CORRELATION
This 15-year-old baseball player underwent significant blunt trauma to the right temple area by a baseball. He briefly lost consciousness, likely due to the concussion of the baseball. After waking up, he had no neurological deficits; however, after 4 h, there were signs of increased intracranial pressure. The most likely explanation is disruption of the middle meningeal artery, which underlies the temporal bone. Over time, the hematoma formed, putting pressure on the underlying brain tissue. The ipsilateral pupil was affected by compression of the oculomotor nerve (CN III) by the temporal lobe of the brain. This scenario of a loss of consciousness followed by a lucid interval and a second loss of consciousness is very typical for epidural hematoma. Because this is arterial bleeding, rapid expansion of the hematoma is typical. Emergent cerebral decompression and surgical control of the bleeding are paramount.


APPROACH TO:
Meninges and Arterial Supply to Brain

OBJECTIVES
1. Be able to list the meningeal layers
2. Be able to identify the dural folds and associated dural sinuses
3. Be able to describe the vascular supplies to the meninges and underlying brain

DEFINITIONS
PACHYMENINX: The thick meningeal layer, that is, the dura mater.

LEPTOMENINX: The thin meningeal layers, that is, the arachnoid and pia maters together.

DURAL SINUS: Cavity filled with venous blood formed by a split in the two layers of dura mater, the periosteal and meningeal layers. Blood drains from the system of sinuses into the internal jugular vein.

PTERION: A landmark on the lateral surface of the skull formed by the junction of the frontal, parietal, temporal, and sphenoid bones. It usually has an H-shaped appearance.


DISCUSSION
As in the spinal cord, three meningeal layers cover the brain: the dura mater, arachnoid mater, and pia mater. The dura mater is a thick, strong membrane (pachymeninx) that is closely apposed to the deep surface of the cranium. Immediately deep to the dura is the arachnoid layer, a thin, nearly transparent membrane that adheres to the deep surface of the dura. The arachnoid layer is separated from the brain by the subarachnoid space, which is filled with CSF. The pia mater is a thin layer attached to the surface of the brain itself. The arachnoid and pia layers together may be referred to as the leptomeninges.

The dura mater that covers the external surface of the brain consists of two layers, an external periosteal layer attached to the bone and an internal meningeal layer. The internal layer forms folds that separate the major lobes of the brain. The falx cerebri courses along the midline and separates the left and right cerebral hemispheres. Running at right angles, the tentorium cerebelli separates the two lobes of the cerebrum from the cerebellum. On the inferior surface of the tentorium is attached the small falx cerebelli, which also runs along the midline and partially separates the cerebellum into lobes. Another important dural infolding the diaphragma sellae, covers the pituitary fossa.

Normally, the two dural layers are tightly apposed, but they may split to form the dural sinuses (Figure 44-1). The major dural sinuses are the superior sagittal sinus, which courses along the superior edge of the falx cerebri, and the transverse sinus, which courses along the posterior border of the tentorium cerebelli. The transverse sinus continues laterally as the sigmoid sinus and empties into the internal jugular vein. On the inferior surface of the falx cerebri, the inferior sagittal sinus continues as the straight sinus after joining the great vein of Galen, which drains the brain. The superior, straight, and transverse sinuses come together at the confluence of sinuses, a landmark on the internal surface of the occipital bone. Other important sinuses are the superior and inferior petrosal sinuses and the cavernous sinus.

The vessels that supply the dura mater are branches of the middle meningeal artery. This artery arises in the infratemporal fossa from the first part of the maxillary artery and enters the cranial cavity through the foramen spinosum. The artery runs within the dura mater and separates into anterior and posterior divisions. An external landmark for the middle meningeal artery is the pterion, where the frontal, parietal, temporal, and sphenoid bones converge. The vessels that supply the brain arise from the circle of Willis (see Case 46 for more details). This anastomotic formation originates from the internal carotid and vertebral arteries. The major branches tend to course along the surface of the brain and give off penetrating branches.

Epidural Hematoma anatomy

Figure 44-1. The dura and meninges: 5 = superior sagittal sinus, 6 = inferior sagittal sinus, 18 = lateral lacuna, 19 = emissary vein (connects sinuses to scalp veins), 20 = arachnoid granulation (resorption of cerebrospinal fluid). (Reproduced, with permission, from the University of Texas Health Science Center, Houston Medical School.)

Head trauma can result in damage to vessels and internal bleeding. Blood accumulates in potential spaces surrounding the brain, expanding their volume, and placing pressure on the brain. The site of accumulation is characteristic of the type of vessel that is damaged. For example, rupture of the middle meningeal artery will lead to accumulation of blood in the epidural potential space, between the external periosteal layer of the dura and the calvaria. Blood from a cerebral artery due, for example, to a ruptured cerebral aneurysm, will accumulate in the subarachnoid space. Head trauma may result in rupture of veins as they enter a sinus, usually resulting in accumulation of blood in the subdural potential space between the dural and arachnoid layers. These veins may be cerebral veins that drain the brain or emissary veins that drain the scalp.


COMPREHENSION QUESTIONS

44.1 A 35-year-old man developed an intracranial hemorrhage when one of the meningeal arteries ruptured. Anatomically, where is the hematoma located?
    A. Immediately superficial to the dura
    B. Immediately deep to the dura
    C. Within the subarachnoid space
    D. Within the brain parenchyma

44.2 A 1-month-old infant is seen in the emergency department because of lethargy and seizures. After careful questioning, it was discovered that the infant was shaken before the change in mental status. Which vessels are most likely to be injured?
    A. Meningeal arteries
    B. Meningeal veins
    C. Emissary veins
    D. Middle cerebral arteries

44.3 A 21-year-old man is brought into the emergency room after being hit in the head with a baseball bat. The neurosurgeon suspects that the skull fracture and underlying hematoma occurred at the junction of the four major bones of the skull. Which of the following describes this region?
    A. Bregma
    B. Lambda
    C. Pterion
    D. Nasion


ANSWERS
44.1 A. Injuries to the meningeal arteries lead to epidural hematomas.

44.2 C. Infants who are shaken are vulnerable to laceration of the emissary veins that are found below the dura. Thus, they often develop subdural hematomas.

44.3 C. The pterion is a landmark of the skull where the four major bones of the skull (frontal, parietal, temporal, and sphenoidal) come together. It is also the thinnest part of the skull.


ANATOMY PEARL
 The dura mater, which covers the external surface of the brain, consists of two layers, an external periosteal layer attached to the bone and an internal meningeal layer.

 An external landmark for the middle meningeal artery is the pterion, where the frontal, parietal, temporal, and sphenoid bones converge.

 The vessels that supply the dura mater are branches of the middle meningeal artery; injuries to these vessels lead to epidural hematomas.

 Blood from ruptured cerebral arteries, such as those due to a ruptured cerebral aneurysm, will accumulate in the subarachnoid space.

References

Gilroy AM, MacPherson BR, Ross LM. Atlas of Anatomy, 2nd ed. New York, NY: Thieme Medical Publishers; 2012:524−525, 634−635. 

Moore KL, Dalley AF, Agur AMR. Clinically Oriented Anatomy, 7th ed. Baltimore, MD: Lippincott Williams & Wilkins; 2014:865−874, 876−877. 

Netter FH. Atlas of Human Anatomy, 6th ed. Philadelphia, PA: Saunders; 2014: plates 101−103.

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