Definition
Subdural effusion, also known as subdural hydroma, is mostly an accumulation of cerebrospinal fluid that occurs in the subdural space after trauma.
Subdural effusion accounts for 0.5% to 1% of craniocerebral trauma and often occurs in one or both frontotemporal areas, with bilateral frontal areas being more common.
Subdural effusion can be divided into acute and chronic, generally acute is rare and forms within a few hours, chronic may have a pericardium.
Causes of formation
The surface of the brain consists of three layers of perimembranes, from the outside to the inside in the order of dura, arachnoid and soft membranes, to the brain its support.
Cerebrospinal fluid is produced by the choroid plexus within the ventricles of the brain and distributed in the ventricles and subarachnoid space, which has a nutritional, shock cushioning, intracranial pressure regulating and protective effect on the brain. The subdural fluid is formed by the cerebrospinal fluid entering the subdural space.
Disease characteristics
1, the effusion mostly occurs in patients with primary craniocerebral injury with occipital landing and GCS 3-12 points at the time of admission.
2. Most patients have cerebral contusions and subarachnoid hemorrhage, especially frontotemporal cerebral contusions are common.
3, the site of fluid accumulation in the frontotemporal area on the curtain or the adjacent parts of the wave, mostly occurring in the hedge of force, occurring in the subcurtain is very rare.
4, primary craniocerebral injury is mild, there may be no or only transient impaired consciousness after the injury, and coma or deepening of impaired consciousness with the increase of fluid accumulation.
Fractal performance
1, receding type: young adults are common, generally no obvious symptoms of increased intracranial pressure, or only in the early stages of mild symptoms of increased intracranial pressure, and then gradually improve, no positive signs of the nervous system. It can be explained by the theory of arachnoid rupture, that is, when the head is traumatized, the arachnoid membrane, which is closely adherent to the lateral fissure, optic cross area and pterygoid crest, is torn, resulting in the outflow of cerebrospinal fluid to accumulate in the subdural cavity, which is gradually absorbed and reduced later.
2.Stable type: The majority of patients are elderly, most of them have dizziness, lightheadedness, nausea, vomiting, euphoria, apathy, depression and memory loss as the main manifestations, and there are usually no positive neurological signs related to subdural fluid accumulation. Long-term observation of this type can be transformed into a fading or evolving type.
3.Progressive type: It is common in pediatric patients. The main manifestation is progressive intracranial pressure increase, the patient may have light hemiparesis, aphasia, mental abnormalities, infants and children may have similar hydrocephalus performance, if combined with brain parenchymal injury, can be accompanied by impaired consciousness and pathological signs.
4.Evolutionary type: The clinical characteristics are polarization of the age of onset, often occurring in children under 10 years old or in elderly people over 60 years old, which may be related to the larger subdural cavity in children and elderly people. It often occurs within 22-100 days after the effusion. During conservative treatment, the effusion can transform into a hydroma, and chronic hematoma due to pericardial hemorrhage occurs after pericardial formation, which often occurs after 1 month of effusion. In contrast, early surgery interrupts the process of fluid transformation into hydatid and pericardial formation, so the evolution of traumatic subdural fluid into chronic subdural hematoma is not likely to occur in surgically treated cases.
Diagnosis
1. History of head trauma.
2.Signs or symptoms of the nervous system are present.
3, Imaging examination can confirm the diagnosis. ct shows a crescentic hypodense area on the top of the frontal temporal area, often into the anterior part of the longitudinal fissure, with brain tissue compression, and a ct value of 0-10Hu.
Differential diagnosis
Chronic subdural hematoma: the hematoma is generally high signal in T1 and T2, and the effusion is consistent with the signal of cerebrospinal fluid, showing T1 low signal and T2 high signal, which can be differentiated.
Treatment
1.Non-surgical treatment.
(1) Use cautiously or not to use dehydrating agents to avoid the increase of fluid accumulation due to low cranial pressure.
(2) Apply neurotrophic drugs, cerebral vasodilators, drugs that inhibit cerebrospinal fluid secretion, hyperbaric oxygen therapy, etc., in order to improve cerebral blood circulation and metabolism and provide the possibility for the expansion of brain tissue to reset and narrow the subdural space.
2.Surgical treatment.
(1) Principles.
(1) Eliminate the cerebral pressure on the fluid accumulation.
(2) Eliminate the cause of fluid accumulation.
(3) Eliminate the cystic cavity of fluid accumulation.
Only if the above three principles are met, can we fundamentally prevent the recurrence of effusion and achieve the purpose of complete cure.
(2) Surgical indications.
(1) If there are clinical symptoms of neurological compression or epileptic seizures, surgery should be used to remove the effusion and release the compression, regardless of the amount of effusion.
(2) Those with supratentorial fluid volume >25ml and subratentorial >8ml should be treated surgically even if there is no neurological compression to facilitate recovery.
③Those with heavy occupying effect, obvious symptoms of cranial hypertension, and imaging examination (CT or MRI) showing ventricular and cerebral pool compression, deformation, and midline shift >10mm.
(iv) Infants and children with frontal anterior gap >6mm.
(3) Surgical modalities.
①Puncture and drainage.
②Patients with unclosed fontanelle are treated with a common intravenous 7-gauge trocar and continuous drainage by percutaneous lateral fontanelle puncture.
③In case of combined intracranial hematoma, severe cerebral contusion and signs of brain herniation, early craniotomy should be performed to remove the hematoma and fluid and decompress the bone flap.
(4) Internal shunt: Although the clinical symptoms improve after external drainage, the effusion does not decrease or increases again or the clinical symptoms worsen after the drainage tube is removed.
(4) The effect of surgery lies in.
(1) The drainage effectively reduced the intracranial pressure and blocked the vicious cycle of increased pulsatile action due to intracranial hypertension.
(ii) Removal of fluid with high protein content that cannot be easily absorbed.
③Subdural drainage facilitates the exudate of brain tissue to flow out of the surface of the brain without contributing to or aggravating cerebral edema by seeping into the tissue interstices.
3.Prevention of brain injury.
The drainage tube should be strictly biased in the direction of the dura mater and should not adhere to the brain tissue so as not to damage the brain tissue during intubation or extubation.
4.Postoperatively, attention should be paid to replenishing isotonic fluid, elevating the drainage tube 375px, maintaining normal cranial pressure, and taking a flat or head-down position if necessary.