Epidural hematoma overview

# Classification
Epidural hematoma may be classified to into three groups: Traumatic epidural hematoma which is the main cause of epidural hematoma, spontaneous spinal epidural hematomas and postoperative epidural spinal hematoma.

# Pathophysiology
Epidural hematoma is the result of the bleeding within the epidural space, which lies between dura mater and skull bone. The main cause of epidural hematoma is typically head injury that results in a break of the temporal bone and bleeding from the middle meningeal artery in the epidural space. Because the bleeding is caused by arterial rupture, it has a high tendency to progress and it causes a hematoma in epidural space. Progression of bleeding may expand the hematoma and cause increasing of the intracranial pressure and it may lead to brain herniation. Occasionally epidural hematoma may occur as a result of a Bleeding disorders or blood vessel malformation or after CNS surgery or lumbar acupunctures or Spinal injections or metastatic cancer and sometimes is may occur spontaneously.

# Causes
The leading cuase of epidural hematoma is head trauma. Other common causes of epidural hematoma include: Spinal trauma,  bleeding disorders, blood vessel malformation, CNS surgery, dengue virus infection, lumbar acupunctures, spinal injections, metastatic cancer, sickle cell anemia and kummell's disease.

# Differentiating Xyz from Other Diseases
Epidural hematoma must be differentiated from other diseases that cause severe headache such as subarachnoid hemorrhage, Subarachnoid hemorrhage, meningitis, intracranial mass, cerebral hemorrhage, cerebral infarction, intracranial venous thrombosis, migraine, pituitary apoplexy, and lymphocytic hypophysitis.

# Epidemiology and Demographics
Epidural hematoma occurs in approximately 2000 per 100,000 of patients with head injury. Epidural hematoma is the cause of 5% to 15% of fatal head injuries. Approximately 85% to 95% of patients with epidural hematoma have an overlying skull fracture. The in-hospital mortality rate of epidural hematoma in young patients with epidural hematoma is approximately 4800 per 100,000 individuals with a case-mortality rate of 4.8%. Patients of all age groups may develop epidural hematoma as the main cause of epidural hematoma is traumatic head injury. There is no racial predilection to epidural hematoma.Epidural hematoma affects men and women equally.

# Risk Factors
The most potent risk factor in the development of epidural hematoma is Head trauma. Other risk factors include: Spinal trauma, bleeding disorders, anticoagulant drugs usage, blood vessel malformation, CNS surgery, lumbar acupunctures ,spinal injections, metastatic cancer, sickle cell anemiaand kummell's disease.

# Screening
There is insufficient evidence to recommend routine screening for epidural hematoma.

# Natural History, Complications, and Prognosis
If left untreated, patients with epidural hematoma may progress to develop permanent paraplegia, loss of sensation, brain herniation, coma and death. Common complications of epidural hematoma include: brain herniation, death, post-traumatic seizures, visual problems, persistent paraplegia, Coma, loss of sensation, priapism, disturbed circulation of the cerebrospinal fluid and Urinary retention. Prognosis is generally good in patients treated surgically without delay. In patients with acute epidural hematoma the surgery in an interval under two hours leads to 17% mortality rate and 67% of good recoveries but in patients who recover after an interval of more than two hours the mortality rate is 65% and good recovery rate is 13%. Overall mortality rate of patients with epidural hematoma is approximately 25%. The percentages of overall good recoveries and minimal neurologic deficit in patients with epidural hematoma is approximately 58%. The prognosis is worse in older patients and in patients with concomitant injuries of other body regions.

# Diagnosis

## Diagnostic Study of Choice
The CT scan is the gold standard test for the diagnosis of epidural hematoma. The following findings on performing CT scan are confirmatory for epidural hematoma: Bi-convex (or lentiform) shaped hematoma in epidural space which can cross the dural reflections unlike a subdural hematoma but it does not cross skull's suture lines where the dura tightly adheres to the adjacent skull, depressed skull fracture in some cases of epidural hematoma, midline shift of brain tissue, subfalcine herniation and uncal herniation. Among patients with head trauma CT scan is indicated for detecting epidural hematoma and other kind of intracranial hemorrhages in patients with: age > 60 years, glasgow Coma Scale under 15, Headache, Vomiting, Loss of consciousness, Amnesia, alcohol or drug intoxication. Screening for cervical spinal hematoma by CT scan is recommended among patients with acute onset of hemiparesis, specially when they are associated with neck pain. MRI is the preferred imaging study for diagnosis of spinal epidural hematoma. In patients with spinal epidural hematoma findings on MRI suggestive of spinal epidural hematoma include: A variable signal intensity( Isointensity to cord in T1-weighted images and Hyperintensity with areas of hypointensity in T2-weighted images), capping of epidural fat, direct continuity with the adjacent osseous structures and compression of epidural fat, subarachnoid sac, and spinal cord. MRI is sensitive for diagnosis of intracranial epidural hematoma but it is rarely used for diagnosis of it because of its limited availability and because more time is needed to prepare the patients for MRI.

## History and Symptoms
Patients with epidural hematoma may have a positive history of: Head trauma, spinal trauma, Bleeding disorders, blood vessel malformation and NS surgery. In traumatic cases of epidural hematoma, patients may develop signs and symptoms right after trauma, or weeks after that. Some patients with epidural hematoma may experience a lucid interval which is a period of time in which patient regains consciousness after a short period of unconsciousness. after lucid interval the sign and symptoms of epidural hematoma may get worse. The most common symptoms of epidural hematoma include: Severe headache, nausea and vomiting, dizziness, drowsiness or altered level of alertness, enlarged pupils, weakness and slurred speech. Less common symptoms of epidural hematoma include: seizures, unconsciousness and visual disturbance. As the hematoma expands, epidural bleeds can become large and raise intracranial pressure, causing the brain herniation in which the brain stem may be compressed and causing unconsciousness, bradycardia and irregular respiration or apnea.

## Physical Examination
Findings in physical examination of patients with epidural hematoma may vary depend on the site and size of the hematoma. In patients with cranial epidural hematoma various focal neurologic signs may be seen depend on the site of hematoma. Physical examination of patients with cranial epidural hematoma is usually remarkable for loss of consciousness, unilateral diminished deep tendon reflexes, unilateral fixed mydriasis and abnormal pupillary reflex, down and out positioned eyes, loss of vision in contralateral side of hematoma and abnormal vertical gaze, unilaterally muscle weakness and unilateral sensory loss.
Glasgow coma scale in most patients with epidural hematoma is reduced. In patients with brain herniation due to the epidural hematoma respiratory arrest and Cushing's triad(hypertension, bradycardia, and irregular respiration) may be seen. Findings in neck examination of patients with spinal epidural hematoma is usually include stiffness and tenderness.

## Laboratory Findings
Laboratory studies should also be considered in all patients with epidural hematoma, including: A complete blood count to check for thrombocytopenia, Coagulation studies (PTT, PT/INR) to check for coagulopathy and Basic metabolic panel to check for electrolyte abnormalities.

## Electrocardiogram
There are no ECG findings associated with epidural hematoma.

## X-ray
Linear fractures in the cranial bones may be presesnt in skull X ray in patients with traumatic cranial epidural hematoma.

## Echocardiography and Ultrasound
There are no echocardiography/ultrasound findings associated with epidural hematoma.

## CT scan
The CT scan is the gold standard test for the diagnosis of epidural hematoma. The following findings on performing CT scan are confirmatory for epidural hematoma: Bi-convex (or lentiform) shaped hematoma in epidural space which can cross the dural reflections unlike a subdural hematoma but it does not cross skull's suture lines where the dura tightly adheres to the adjacent skull, depressed skull fracture in some cases of epidural hematoma, midline shift of brain tissue, subfalcine herniation and uncal herniation. Among patients with head trauma CT scan is indicated for detecting epidural hematoma and other kind of intracranial hemorrhages in patients with: age > 60 years, glasgow Coma Scale under 15, Headache, Vomiting, Loss of consciousness, Amnesia, alcohol or drug intoxication. Screening for cervical spinal hematoma by CT scan is recommended among patients with acute onset of hemiparesis, specially when they are associated with neck pain.

## MRI
MRI is the preferred imaging study for diagnosis of spinal epidural hematoma. In patients with spinal epidural hematoma findings on MRI suggestive of spinal epidural hematoma include: A variable signal intensity( Isointensity to cord in T1-weighted images and Hyperintensity with areas of hypointensity in T2-weighted images), capping of epidural fat, direct continuity with the adjacent osseous structures and compression of epidural fat, subarachnoid sac, and spinal cord. MRI is sensitive for diagnosis of intracranial epidural hematoma but it is rarely used for diagnosis of it because of its limited availability and because more time is needed to prepare the patients for MRI.

## Other Imaging Findings
There are no widely used other imaging findings associated with epidural hematoma.

## Other Diagnostic Studies
There are no widely used other diagnostic studies associated with epidural hematoma.

# Treatment

## Medical Therapy
The mainstay of treatment for epidural hematoma is urgent surgery.

## Surgery
Surgery is the mainstay of treatment for epidural hematoma. An epidural hematoma greater than 30 cm3 should be surgically evacuated regardless of the patient's Glasgow Coma Scale (GCS) score. An epidural hematoma less than 30 cm3 and with less than a 15-mm thickness and with less than a 5-mm midline shift in patients with a GCS score greater than 8 without focal deficit can be managed nonoperatively with serial computed tomographic scanning and close neurological observation in a neurosurgical center. Acute epidural hematoma with a small amount of bleeding(less than 50 mL)may be treated by minimal invasive surgery methods which avoids craniotomy.

## Primary Prevention
There are no established measures for the primary prevention of epidural hematoma.

## Secondary Prevention
There are no established measures for the secondary prevention of epidural hematoma.