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Subdural hematoma

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High Yield Notes

18 pages

Flashcards

Subdural hematoma

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Questions

USMLE® Step 1 style questions USMLE

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A 30-year-old woman is brought to the emergency department following a fall during a climbing trip. Her partner, who accompanied her, reports that the patient fell from a 4-meter height and hit her head. En route to the hospital, the patient is comatose and unresponsive. Glasgow Coma Score is 3. She is sedated and intubated. On arrival, her temperature is 36.0°C (96.8°F), pulse is 43/min, respirations are 7/min and irregular, and blood pressure is 200/70 mmHg. On physical examination, her arms are stiff and bent, with clenched fists and outstretched legs. Both pupils are fixed and dilated. A non-contrast CT is obtained and shows a large biconvex-shaped lesion. Which of the following additional findings is most likely to be present?  

Memory Anchors and Partner Content

External References

First Aid

2024

2023

2022

2021

Alcoholism p. 589

subdural hematomas p. 528

Subdural hematomas p. 528

child abuse sign p. 573

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Transcript

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Content Reviewers

Rishi Desai, MD, MPH,Yifan Xiao, MD

Subdural hemorrhage can be broken down. Sub means below, “dural” which refers to the outermost protective layer of the brain, which is called dura mater, and “hemorrhage” refers to bleeding. So, a subdural hemorrhage is when there’s bleeding below the dura mater.

OK - let’s start with some basic brain anatomy. The brain is protected by 3 thin layers of tissue called the meninges which covers the brain and spinal cord.

The inner layer of the meninges is the pia mater, the middle layer is the arachnoid mater, and the outer layer is the dura mater. The pia and arachnoid maters, are also called leptomeninges.

Between the leptomeninges, there’s the subarachnoid space, which houses cerebrospinal fluid, or CSF.

CSF is a clear, watery liquid which is pumped around the spinal cord and brain, cushioning them from impact and bathing them in nutrients. The outer membrane, the dura mater consists of two layers.

The internal layer of the dura mater lies above the arachnoid mater - the two are separated by the subdural space. The external layer of the dura mater adheres to the inner surface of the skull.

These two layers of the dura mater travel together, but at certain spots, the internal layer of the dura mater separates from the external one to form the meningeal folds.

The meningeal folds help divide the sections of the brain like the falx cerebri which separates the two hemispheres of the cerebrum, and the tentorium, which covers the cerebellum and separates it from the cerebrum. The subdural space plays a major role in venous blood drainage in the brain.

Summary

A subdural hematoma is a type of hematoma where the blood gathers between the dura mater and the brain. It comes from the rupture of the bridging veins found within the subdural space, often due to head trauma, especially in the elderly, babies, and individuals that abuse alcohol.

Diagnosis requires brain imaging like a CT scan, which shows an acute subdural hemorrhage as a hyperdense blood collection, whereas a chronic subdural hemorrhage appears as a hypodense blood collection. It's also important to note that subdural hematomas cross suture lines and follow the contour of the brain forming a crescent shape, unlike epidural hematomas which don't cross suture lines. Treatment for a subdural hematoma includes surgery to remove the blood clot, medications to reduce swelling and pressure on the brain or observation.

Sources

  1. "Robbins Basic Pathology" Elsevier (2017)
  2. "Harrison's Principles of Internal Medicine, Twentieth Edition (Vol.1 & Vol.2)" McGraw-Hill Education / Medical (2018)
  3. "Pathophysiology of Disease: An Introduction to Clinical Medicine 8E" McGraw-Hill Education / Medical (2018)
  4. "CURRENT Medical Diagnosis and Treatment 2020" McGraw-Hill Education / Medical (2019)
  5. "Pathophysiology of chronic subdural haematoma: inflammation, angiogenesis and implications for pharmacotherapy" Journal of Neuroinflammation (2017)
  6. "Pathophysiology of chronic subdural haematoma: inflammation, angiogenesis and implications for pharmacotherapy" Journal of Neuroinflammation (2017)