Chronic Subdural Fluid Collection in Children
Introduction In the pediatric population, chronic subdural fluid collection is group of related condition termed as extracerebral (or extra-axial) fluid collection (1). Chronic subdural fluid collection can present as chronic subdural hematoma or subdural effusion (2). The term subdural hygroma, subdural hydroma, chronic subdural hematoma and beningn extracerebral fluid collection etc have been used very loosely in past to describe the same entity. While the condition of benign external hydrocephalus (benign extra cerebral fluid collection) has been recognized as different entity from above described entities, as it is a self limiting disease of infancy (3). Modern neuroimaging techniques, however have greatly advanced our understanding of these conditions. Surprisingly not much literature exists on the subject, and publications before the advent of modern computed tomography (CT) and magnetic resonance imaging-MRI (1). It is an entity of common interest to pediatricians, physicians and neurosurgeons. The author highlights his experience of subdural fluid collection in small children of less than 2 year age, the role of conservative treatment is emphasized. Pathophysiology and Terminology Excessive fluid within the subarachnoid space occurs with communicating hydrocephalus and in a selflimited condition known by various terms, including benign expansion of the subarachnoid spaces and benign external hydrocephalus (1). According to other theory, the benign external hydrocephalus is thought to occur because of the atersia of arachnoid villi leading to failed CSF absorption and it’s (CSF) consequent accumulation in subarachnoid space (4). Hence this entity is different from other subdural fluid collections i.e. effusion, haematoma or hygroma. Chronic accumulation of fluid within the subdural space may occur as the results of
one or more of three distinct processes. The most straight forward of these occurs when liquefication of an acute subdural hematoma results in chronic subdural hematoma (CSH) formation. It has been postulated that the thick viscous fluid, increases in volume because of gradients in oncotic pressure. Although this may occur as early as blood and proteins degrade, most investigators believe that rebleeding is the main agent causing persistence of the subdural hematoma (1). The second type of subdural fluid collection occurs after an opening in the arachnoid, which allows CSF to enter the subdural space. The CSF mixes with varying amounts of blood, resulting in a thin xanthochromic fluid, sometimes termed a subdural hygroma (1). The third type of subdural fluid accumulation is purulent. Subdural empyemas may result from direct extension of sinusitis or otitis media into the epidural space and then the subdural space. Purulent subdural collections are also occasionally seen after episodes of bacterial meningitis, especially due to haemophilus influenza (1). Causes The most common cause of subdural fluid collection in children is meningitis in about 42% cases (2) (Fig.1).
Fig.1. MRI saggittal view showing subdural fluid collection, which occurred following meningitis.
From The Department of Neurosurgery, Sanjay Gandhi Postgraduate Institute of Medical Sciences, Lucknow, U.P. (India). Correspondece to: Dr. Raj Kumar, Associate Professor, Deptt. of Neurosurgery Sanjay Gandhi PGIMS Lucknow - 226014, U.P (India). Vol. 7 No. 1, January-March 2005
JK SCIENCE The second common cause is head injury in about 24% cases (2) (Table 1). Table. 1 Etiologies of subdural fluid collection. Sl.No. 1. 2. 3. 4. 5. 6. Etiology Meningiti Head Injury Unknown Postoperative Child Abuse Hemorrhagic diathesis Percentage (%) 42 24 15 14 3 2
Out of our 21 children (of subdural fluid collection) studied by us over a period of 9 years, subclinical or clinical meningitis was responsible for it in 4, head trauma in 5, following surgery...
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