Postoperative complications from intracranial haematoma are uncommon after elective brain surgery and rare after elective spinal surgery (< 3%). The principles of meticulous haemostasis and avoidance of dead spaces are common to both cranial and spinal surgery in preventing postoperative haematoma.16 The larger the craniotomy flap, the greater is the risk of a haematoma. This risk increases significantly with emergency trauma surgery because of the wider area of damage.
The potential space under a large bone flap was identified as a significant risk factor in 59 patients who developed postoperative haematoma that required evacuation. Most of these postoperative haematomas were extradural. These 59 patients were from a total number of 850 patients who were admitted with severe head injuries and had intracranial haematoma evacuated. Factors predisposing to a recurrent haematoma included high alcohol intake, brain atrophy, coagulopathy and initial intradural bleed. These injuries and major surgery may consume platelets and clotting factors. Alcohol itself is known to be a cause of thrombocytopenia, and there may also be sub-clinical liver damage. Patients with significant postoperative haematomas, most commonly, deteriorate within 24 hours ofsurgery. The haematomas seen can reflect bleeding at the craniotomy site in either the intradural or extradural spaces due to inadequate surgical haemostasis at the initial procedure or may reflect other factors, such as, a coagulopathy. Therefore, before any re-operation, the full clotting profile must be reviewed. The incidence of haematomas is also dependent upon the criteria used to make the diagnosis. Routine postoperative CT brain scans often demonstrate an accumulation of blood under the bone flap. Generally, this collection does not cause any mass effect or shift and will resolve without evacuation. Patients with severe head injuries routinely undergo a second CT brain scan 24 hours after admission because of the risk of rebleeding from existing surface contusions that can enlarge, coalesce, and re-bleed causing local mass effect.
Extradural haematomas, after both elective and emergency cran-iotomies, can be prevented by attention to securing haemostasis at all stages of the operation. The scalp edges are secured before the bone flap is fashioned. After the bone flap is elevated, haemostasis is secured in the extra-dural space and hitch sutures (tacking sutures) placed around the edges ofthe bone margins. These tacking sutures should only go through the outer layer of the dura. If the suture goes through the full thickness of the dura, the cortex or cortical vessels may be injured and result in a subdural haematoma. In large craniotomies, the extradural space can be reduced further by tacking the centre of the dural flap to the middle of the skull flap (Poppen suture). Titanium liga clips are routinely used to control bleeding from the dural edges.
There is an overall risk of at least 1% for postoperative haema-tomas, after elective neurosurgery. There is however considerable variation in incidence for different pathologies and different ages. Brain tumours can pose intra-operative and postoperative difficulties with haemostasis. The highest incidence of postoperative haematoma after surgery for intracranial tumours is seen in the elderly, particularly after the excision of a meningioma. On an average, 7% of patients over 70 years of age require re-operation for evacuation of a haematoma that usually occurs in the tumour bed. This compares to 2% incidence of evacuated postoperative haematoma in patients undergoing surgery for intrinsic tumours. Coagulopathy and thrombocytopenia are recognised as general risk factors. Size, location, or histological subtype of the meningioma did not influence the risk of postoperative bleeding. The other potential factors such as dural sinus invasion, extent of tumour resection and degree of tumour vascularity did not influence the overall risk of a postoperative haematoma. Why age on its own influences the risk of a postoperative haematoma has not been fully answered. Changes in the blood vessels and poor platelet function have been suggested. There are also the structural factors with brain atrophy and failure of the brain to re-expand. In addition the elderly may have a different clotting profile after surgery, compared with younger patients who have a higher risk of thrombocytopenia. Open operations are routine for extrinsic tumours, but intrinsic tumours such as gliomas are often deep and situated in eloquent areas. Therefore a stereotactic biopsy is the safest approach. The risk of bleeding from this blind procedure is less than 2% and is again related to the vascularity of the tumour as well as the other general risk factors. It is of interest that there is no statistically significant difference of haematoma formation between stereotactic procedures for tumour biopsy and functional procedures (e.g. implantation of deep brain electrodes to control tremor).
Neurovascular surgery has undergone considerable revision in the last decade, with less open procedures being followed. Today, neuroradiologists undertake the majority of interventional procedures for aneurysms and AVMs. These endovascular procedures routinely use intravenous heparin during the interventional procedure. Bleeding can occur if the aneurysm ruptures during manipulation of the guide wire or placement of the coil. In these situations, the aneurysm is rapidly packed with further coils, and protamine may be used to reverse the heparin. The overall risk of complications from bleeding is 2%. Emergency ventricular drainage for obstructive hydrocephalus may be required soon after coiling of an aneurysm. This carries an increased risk of intra-parenchymal bleeding because of the presence of the heparin.
The outcome of patients with postoperative intracranial haematomas is poor. Death occurs in 15% of the cases, and 40% are left with significant disability. The management of postoperative haematoma will depend on the location of the haemorrhage and the presence or absence of any symptom. Subgaleal scalp haematomas are best left to resolve on their own, without aspiration. Repeat aspirations are likely to introduce infection. The recognition and management of symptomatic intracranial haematomas generally require an urgent response. At the first signs of neurological deterioration, a CT brain scan is requested to exclude other causes for the patients' clinical condition such as brain swelling. In certain circumstances, when there is no time for the CT scan, it may be appropriate to make the diagnosis on clinical grounds and take the patient directly to the operating room. Irreversible damage can occur if the condition is not recognised promptly. Extradural haematoma should be suspected in any patient who develops a new postoperative neurological deficit.
In a case of a symptomatic progressive extradural haematoma, immediate evacuation is essential. If a coagulopathy is present, it should be corrected in consultation with the haematology service. Post-craniotomy patients with a coagulopathy, who have no symptoms or signs of an emerging haematoma, are closely monitored. It is preferable to correct the coagulopathy before it causes haemorrhage, rather than treat the haemorrhage.
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