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Subdural hygroma | |
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Subdural hygroma, frontal and temporal. Man of 80 years old. | |
Specialty | Neurology |
A subdural hygroma (SDG) is a collection of cerebrospinal fluid (CSF), without blood, located under the dural membrane of the brain. Most subdural hygromas are believed to be derived from chronic subdural hematomas. They are commonly seen in elderly people after minor trauma but can also be seen in children following infection or trauma. One of the common causes of subdural hygroma is a sudden decrease in pressure as a result of placing a ventricular shunt. This can lead to leakage of CSF into the subdural space especially in cases with moderate to severe brain atrophy. In these cases the symptoms such as mild fever, headache, drowsiness and confusion can be seen, which are relieved by draining this subdural fluid.
Subdural hygromas require two conditions in order to occur. First, there must be a separation in the layers of the Meninges of the brain. Second, the resulting subdural space that occurs from the separation of layers must remain uncompressed in order for CSF to accumulate in the subdural space, resulting in the hygroma. [1] The arachnoid mater is torn and cerebrospinal fluid (CSF) from the subarachnoid space accumulates in the subdural space. Hygromas also push the subarachnoid vessels away from the inner table of the skull. [2] Subdural hygroma can appear in the first day, but the mean time of appearance is 9 days on CT scan. Subdural hygroma does not have internal membranes that can easily rupture like subdural haematoma, but hygroma can sometimes occur together with hemorrhage to become hematohygroma. [2]
Subdural hygromas most commonly occur when events such as head trauma, infections, or cranial surgeries happen in tandem with brain atrophy, severe dehydration, prolonged spinal drainage, or any other event that causes a decrease in intracranial pressure. [1] This provides the basis for why subdural hygromas more commonly occur in infants and elderly; infants have compressible brains while elderly patients have a greater amount of space for fluid to accumulate due to brain atrophy from age. [1]
Most subdural hygromas are small and clinically insignificant. A majority of patients with SDG will not experience symptoms. However, some commonly reported but nonspecific symptoms of SDG that have been reported include headache and nausea. Focal neurologic deficits and seizures have also been reported but are nonspecific to SDG. [1] Larger hygromas may cause secondary localized mass effects on the adjacent brain parenchyma, enough to cause a neurologic deficit or other symptoms. Acute subdural hygromas can be a potential neurosurgical emergency, requiring decompression. Acute hygromas are typically a result of head trauma—they are a relatively common posttraumatic lesion—but can also develop following neurosurgical procedures, and have also been associated with a variety of conditions, including dehydration in the elderly, lymphoma and connective tissue diseases.
In CT scan, subdural hygroma will have same density as the normal CSF. Meanwhile, in MRI, subdural hygroma will have same intensity with CSF. If iodinated contrast is administered during CT scan, the hygroma will produce high density because of the contrast at 120 kVp. However, at 190 kVp, hygroma with contrast will have intermediate density. [2]
In the majority of cases, if there has not been any acute trauma or severe neurologic symptoms, a small subdural hygroma on the head CT scan will be an incidental finding. If there is an associated localized mass effect that may explain the clinical symptoms, or concern for a potential chronic SDH that could rebleed, then an MRI, with or without neurologic consultation, may be useful.
It is not uncommon for chronic subdural hematomas (SDHs) on CT reports for scans of the head to be misinterpreted as subdural hygromas, and vice versa. Magnetic resonance imaging (MRI) should be done to differentiate a chronic SDH from a subdural hygroma, when clinically warranted. Elderly patients with marked cerebral atrophy, and secondary widened subarachnoid CSF spaces, can also cause confusion on CT. To distinguish chronic subdural hygromas from simple brain atrophy and CSF space expansion, a gadolinium-enhanced MRI can be performed. Visualization of cortical veins traversing the collection favors a widened subarachnoid space as seen in brain atrophy, whereas subdural hygromas will displace the cortex and cortical veins.
Most subdural hygromas that are asymptomatic do not require any treatment. Some might opt to perform a simple burr-holes to alleviate intracranial pressure (ICP). Occasionally a temporary drain is placed for 24-48 hours post op. In recurrent cases a craniotomy may be performed to attempt to locate the location of the CSF Leak. In certain cases a shunt can be placed for additional drainage. Great caution is used when choosing to look for the CSF leak due to them generally being difficult to spot.
Cerebrospinal fluid (CSF) is a clear, colorless body fluid found within the tissue that surrounds the brain and spinal cord of all vertebrates.
Idiopathic intracranial hypertension (IIH), previously known as pseudotumor cerebri and benign intracranial hypertension, is a condition characterized by increased intracranial pressure without a detectable cause. The main symptoms are headache, vision problems, ringing in the ears, and shoulder pain. Complications may include vision loss.
Syringomyelia is a generic term referring to a disorder in which a cyst or cavity forms within the spinal cord. Often, syringomyelia is used as a generic term before an etiology is determined. This cyst, called a syrinx, can expand and elongate over time, destroying the spinal cord. The damage may result in loss of feeling, paralysis, weakness, and stiffness in the back, shoulders, and extremities. Syringomyelia may also cause a loss of the ability to feel extremes of hot or cold, especially in the hands. It may also lead to a cape-like bilateral loss of pain and temperature sensation along the upper chest and arms. The combination of symptoms varies from one patient to another depending on the location of the syrinx within the spinal cord, as well as its extent.
A head injury is any injury that results in trauma to the skull or brain. The terms traumatic brain injury and head injury are often used interchangeably in the medical literature. Because head injuries cover such a broad scope of injuries, there are many causes—including accidents, falls, physical assault, or traffic accidents—that can cause head injuries.
Hydrocephalus is a condition in which an accumulation of cerebrospinal fluid (CSF) occurs within the brain. This typically causes increased pressure inside the skull. Older people may have headaches, double vision, poor balance, urinary incontinence, personality changes, or mental impairment. In babies, it may be seen as a rapid increase in head size. Other symptoms may include vomiting, sleepiness, seizures, and downward pointing of the eyes.
Subarachnoid hemorrhage (SAH) is bleeding into the subarachnoid space—the area between the arachnoid membrane and the pia mater surrounding the brain. Symptoms may include a severe headache of rapid onset, vomiting, decreased level of consciousness, fever, weakness, numbness, and sometimes seizures. Neck stiffness or neck pain are also relatively common. In about a quarter of people a small bleed with resolving symptoms occurs within a month of a larger bleed.
A subdural hematoma (SDH) is a type of bleeding in which a collection of blood—usually but not always associated with a traumatic brain injury—gathers between the inner layer of the dura mater and the arachnoid mater of the meninges surrounding the brain. It usually results from tears in bridging veins that cross the subdural space.
Intracranial hemorrhage (ICH), also known as intracranial bleed, is bleeding within the skull. Subtypes are intracerebral bleeds, subarachnoid bleeds, epidural bleeds, and subdural bleeds.
Epidural hematoma is when bleeding occurs between the tough outer membrane covering the brain and the skull. Often there is loss of consciousness following a head injury, a brief regaining of consciousness, and then loss of consciousness again. Other symptoms may include headache, confusion, vomiting, and an inability to move parts of the body. Complications may include seizures.
Normal-pressure hydrocephalus (NPH), also called malresorptive hydrocephalus, is a form of communicating hydrocephalus in which excess cerebrospinal fluid (CSF) occurs in the ventricles, and with normal or slightly elevated cerebrospinal fluid pressure. As the fluid builds up, it causes the ventricles to enlarge and the pressure inside the head to increase, compressing surrounding brain tissue and leading to neurological complications. The disease presents in a classic triad of symptoms, which are memory impairment, urinary frequency, and balance problems/gait deviations. The disease was first described by Salomón Hakim and Adams in 1965.
Cerebral atrophy is a common feature of many of the diseases that affect the brain. Atrophy of any tissue means a decrement in the size of the cell, which can be due to progressive loss of cytoplasmic proteins. In brain tissue, atrophy describes a loss of neurons and the connections between them. Brain atrophy can be classified into two main categories: generalized and focal atrophy. Generalized atrophy occurs across the entire brain whereas focal atrophy affects cells in a specific location. If the cerebral hemispheres are affected, conscious thought and voluntary processes may be impaired.
Arachnoid cysts are cerebrospinal fluid covered by arachnoidal cells and collagen that may develop between the surface of the brain and the cranial base or on the arachnoid membrane, one of the three meningeal layers that cover the brain and the spinal cord. Primary arachnoid cysts are a congenital disorder whereas secondary arachnoid cysts are the result of head injury or trauma. Most cases of primary cysts begin during infancy; however, onset may be delayed until adolescence.
Psychoorganic syndrome (POS), also known as organic psychosyndrome, is a progressive disease comparable to presenile dementia. It consists of psychopathological complex of symptoms that are caused by organic brain disorders that involve a reduction in memory and intellect. Psychoorganic syndrome is often accompanied by asthenia.
Myelography is a type of radiographic examination that uses a contrast medium to detect pathology of the spinal cord, including the location of a spinal cord injury, cysts, and tumors. Historically the procedure involved the injection of a radiocontrast agent into the cervical or lumbar spine, followed by several X-ray projections. Today, myelography has largely been replaced by the use of MRI scans, although the technique is still sometimes used under certain circumstances – though now usually in conjunction with CT rather than X-ray projections.
Pneumocephalus is the presence of air or gas within the cranial cavity. It is usually associated with disruption of the skull: after head and facial trauma, tumors of the skull base, after neurosurgery or otorhinolaryngology, and rarely, spontaneously. Pneumocephalus can occur in scuba diving, but is very rare in this context.
Kernohan's notch is a cerebral peduncle indentation associated with some forms of transtentorial herniation. It is a secondary condition caused by a primary injury on the opposite hemisphere of the brain. Kernohan's notch is an ipsilateral condition, in that a left-sided primary lesion evokes motor impairment in the left side of the body and a right-sided primary injury evokes motor impairment in the right side of the body. The seriousness of Kernohan's notch varies depending on the primary problem causing it, which may range from benign brain tumors to advanced subdural hematoma.
Midline shift is a shift of the brain past its center line. The sign may be evident on neuroimaging such as CT scanning. The sign is considered ominous because it is commonly associated with a distortion of the brain stem that can cause serious dysfunction evidenced by abnormal posturing and failure of the pupils to constrict in response to light. Midline shift is often associated with high intracranial pressure (ICP), which can be deadly. In fact, midline shift is a measure of ICP; presence of the former is an indication of the latter. Presence of midline shift is an indication for neurosurgeons to take measures to monitor and control ICP. Immediate surgery may be indicated when there is a midline shift of over 5 mm. The sign can be caused by conditions including traumatic brain injury, stroke, hematoma, or birth deformity that leads to a raised intracranial pressure.
A cerebrospinal fluid leak is a medical condition where the cerebrospinal fluid (CSF) surrounding the brain or spinal cord leaks out of one or more holes or tears in the dura mater. A cerebrospinal fluid leak can be either cranial or spinal, and these are two different disorders. A spinal CSF leak can be caused by one or more meningeal diverticula or CSF-venous fistulas not associated with an epidural leak.
Superficial hemosiderosis of the central nervous system is a disease of the brain resulting from chronic iron deposition in neuronal tissues associated with cerebrospinal fluid. This occurs via the deposition of hemosiderin in neuronal tissue, and is associated with neuronal loss, gliosis, and demyelination of neuronal cells. This disease was first discovered in 1908 by R.C. Hamill after performing an autopsy. Detection of this disease was largely post-mortem until the advent of MRI technology, which made diagnosis far easier. Superficial siderosis is largely considered a rare disease, with less than 270 total reported cases in scientific literature as of 2006, and affects people of a wide range of ages with men being approximately three times more frequently affected than women. The number of reported cases of superficial siderosis has increased with advances in MRI technology, but it remains a rare disease.
A sports-related traumatic brain injury is a serious accident which may lead to significant morbidity or mortality. Traumatic brain injury (TBI) in sports are usually a result of physical contact with another person or stationary object, These sports may include boxing, gridiron football, field/ice hockey, lacrosse, martial arts, rugby, soccer, wrestling, auto racing, cycling, equestrian, rollerblading, skateboarding, skiing or snowboarding.