When encountering the acronym SDH in a medical context, the meaning is often unclear. This three-letter abbreviation refers to several distinct concepts, but the most frequent and clinically serious interpretation is Subdural Hematoma, a type of bleeding around the brain. Recognizing the different meanings of SDH helps in understanding the medical information presented.
Subdural Hematoma: The Primary Definition
A Subdural Hematoma (SDH) is a collection of blood that pools on the surface of the brain, located between two protective layers of the meninges: the dura mater (outermost) and the arachnoid mater (middle layer). This accumulation occurs in the subdural space. The condition typically results from a tear in the bridging veins, small vessels that drain blood from the brain’s surface. When these veins are stretched or torn, the resulting hematoma exerts pressure on the underlying brain tissue. SDHs are categorized as acute (symptoms within hours) or chronic (developing slowly over weeks or months).
Causes, Symptoms, and Diagnosis of Subdural Hematoma
Causes
The primary cause of a subdural hematoma is traumatic brain injury, ranging from severe impact to a minor bump. High-speed acceleration injuries, such as those sustained in a car accident, often lead to acute SDH. For older adults or individuals taking blood-thinning medications, a low-impact fall can tear the bridging veins, often resulting in a chronic SDH. This vulnerability in the elderly is partly due to age-related brain atrophy, which stretches the bridging veins and makes them susceptible to rupture.
Symptoms
Symptoms of acute SDH are severe and rapid, reflecting the quick buildup of pressure on the brain. These can include severe headache, nausea and vomiting, slurred speech, sudden weakness on one side of the body, and a rapidly declining level of consciousness. If not addressed quickly, increasing intracranial pressure can lead to seizures, paralysis, or coma. Chronic SDHs often present with more subtle symptoms, such as persistent headaches, confusion, personality changes, or difficulty with walking and balance.
Diagnosis
To confirm a diagnosis and determine the size and location of the blood collection, medical professionals rely on imaging technology. A Computerized Tomography (CT) scan is the fastest and most common initial diagnostic tool, clearly showing the crescent-shaped blood collection around the brain. Magnetic Resonance Imaging (MRI) may also be used to provide a more detailed view of the brain and the hematoma, particularly in less acute cases. These scans are essential for classifying the hematoma and guiding treatment decisions.
Treatment and Recovery for Subdural Hematoma
Management depends on the hematoma’s size, onset speed, and the patient’s neurological status. Small, stable hematomas without significant symptoms may be managed conservatively through careful observation and repeated scans. If the hematoma is large or causes increased pressure symptoms, surgical intervention is necessary to relieve pressure on the brain.
Two primary surgical techniques evacuate the blood. Burr hole trephination involves drilling small holes into the skull to drain the liquid portion of the hematoma. For larger, solid blood clots, a craniotomy is required, which involves temporarily removing a section of the skull bone to access and remove the hematoma directly. The goal of both procedures is to decompress the brain.
Recovery is highly variable, depending on the patient’s age, the extent of the injury, and treatment speed. Even after successful surgery, patients may require extensive rehabilitation, including physical, occupational, and speech therapy. Potential complications include persistent headaches, memory issues, or the risk of recurrence, which may necessitate further surgery.
Secondary Meanings of SDH in Medicine
Beyond the neurological condition, SDH is used in other medical and scientific fields. One meaning is Succinate Dehydrogenase, an enzyme complex found within cellular mitochondria. This enzyme plays a dual role in energy production, participating in both the Krebs cycle and the electron transport chain. Succinate Dehydrogenase converts succinate to fumarate, a fundamental step in cellular respiration. Malfunction or genetic mutations in this enzyme have been linked to diseases, including certain types of cancer and neurodegenerative disorders.
Another meaning of SDH is Social Determinants of Health, a public health concept. These refer to the wide-ranging non-medical factors that significantly influence a person’s health outcomes. These conditions include the circumstances in which people are born, grow, live, work, and age. Public health efforts focused on SDH aim to address these systemic issues to improve overall community health and reduce health inequities.
Examples of Social Determinants of Health
- Economic stability
- Quality of education
- Access to safe housing
- Availability of nutritious food