WHAT IS SUBDURAL HEMATOMA?

Undoubtedly, Subdural hematoma is a condition which involves the accumulation of blood between the dura mater and the subarachnoid mater which are the protective layers of the brain. The blood seeps between the dura mater as well as the arachnoid mater, collecting inside the dura mater (brain’s tough outer lining). For the most part, it occurs from rupture of veins which cross the surface convexities of the cerebral hemispheres resulting from a severe injury to the head or skull. Furthermore, the blood may press against the brain increasing the intracranial pressure which damages the delicate tissue of the brain.

So, as it expands in the subdural space, it raises the Intracranial pressure and deforms the brain. As a result of repeated bleeding and organisation causes a progressive increase in size and shows a laminated appearance. Furthermore, this can be seen in all age groups. In Infants, the cause may be a non-accidental injury, motor vehicle accidents in young adults and fall (due to trauma or any other reason) in older persons. In particular, possible causes for this are as follows:

  • Head injury [most common among younger people] 
  • Brain shrinking (atrophy) [most common among older adults] 
  • Being on medicines to prevent blood clots, such as warfarin, aspirin, and other blood thinners 
  • Cerebrospinal fluid [CSF] leaking

PATHOPHYSIOLOGY

It can be classified into the following groups. They are:

  • Acute Subdural Hematoma
  • Sub – Acute Subdural Hematoma
  • Chronic Subdural Hematoma

ACUTE SUBDURAL HEMATOMA

Acute Subdural Hematoma develops following trauma and consists of clotted blood in the frontoparietal region of the Brain. Moreover, it is the most common type of Subdural Hematoma accounting for 24% of cases of severe head injuries and has the highest mortality rate. The Clinical Manifestations appears during the first 3 days after injury. In this case, the usual mechanism in an Acute Subdural Hematoma is a high-speed impact to the skull. So, this sudden impact can strain the blood vessels within the dura, causing them to rip and bleed resulting in brain injury and even death. 

Following this, Acute subdural hematomas frequently arise from the tearing of bridging veins within the dural border cell layer which results in blood flowing into a potential space within the dura mater. To sum up, bleeding continues via a positive feedback mechanism that causes the Cerebrovenous Pressure to increase as the Intracranial Pressure elevates. So, as the Hematoma enlarges, continued dissection of the border cell layer is seen. This continues until blood begins to coagulate, stopping the border cell layer dissection, and pressure within the Acute Subdural Hematoma cavity rises to equal that in the torn bridging vein or veins.

SUB-ACUTE SUBDURAL HEMATOMA

Sub – Acute Subdural Hematoma develops when the clotted blood in the brain liquefies. Furthermore, the Clinical manifestations appear between 4-21 days after injury. For instance, causes of this involve coagulopathies and ruptured intracranial aneurysms. To conclude, subdural hematomas have even been reported to be caused by intracranial tumours.

CHRONIC SUBDURAL HEMATOMA

Chronic Subdural Hematoma develops mainly with brain atrophy and less likely following trauma. So, it is composed of liquid blood. Furthermore, the Clinical manifestations appear after 21 days of the injury. Cortical bridging veins are thought to be under greater tension as the brain gradually shrinks from the skull and even minor trauma or an injury to the skull can cause one of these veins to tear. Slow bleeding from the low-pressure venous system enables large hematomas to form before clinical signs appear.

Moreover, this results from traumatic injury which causes the tearing of the bridging veins traversing from the brain to the draining dural-venous sinuses. So, this results in the accumulation of venous blood within the subdural space over time. 

SIGNS & SYMPTOMS OF SUBDURAL HEMATOMA

ADULTS

  • Slurred Speech
  • Difficulty in walking
  • Headache
  • Confusion
  • Seizures 
  • Loss of consciousness
  • Nausea and vomiting
  • Weakness or numbness
  • Vision problems
  • Dizziness
  • Sleepiness
  • Coma

INFANTS

  • Bulging Fontanelles (The soft spots of the baby’s skull)
  • Separated Sutures (The areas where growing skull bones join)
  • Feeding problems
  • Seizures
  • High-pitched cry
  • Irritability
  • Increased head size (circumference)
  • Increased sleepiness 
  • Persistent vomiting

RISK FACTORS

  • Chronic alcoholism
  • Epilepsy
  • Coagulopathy
  • Arachnoid cysts
  • Anticoagulant therapy 
  • Cardiovascular disease 
  • Thrombocytopenia
  • Diabetes mellitus
  • Very young or very old age
  • Head injury, such as from car crashes, falls etc
  • Playing high-impact sports
  • Previous brain injury
  • Cerebrospinal fluid leak 

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