Subarachnoid Hemorrhage
Overview
Primary subarachnoid hemorrhage (SAH) refers to the flow of blood into the subarachnoid space after the rupture of blood vessels on the surface of the brain. The annual incidence is 5-20/100,000, and the common causes are intracranial aneurysm, followed by cerebrovascular malformation, hypertensive atherosclerosis, arteritis, anomalous vascular network at the base of the brain, connective tissue disease, hematologic disease, and complications of anticoagulation therapy.
History taking]
1.Onset of the disease: most of them have an acute onset under emotional or exertional conditions.
2. Main symptoms: sudden onset of severe headache, persistent unrelieved or progressive aggravation; mostly accompanied by nausea and vomiting; may have transient disorders of consciousness and mental symptoms such as irritability and delirium, and a few appear to be seizures.
Physical examination]
Meningeal irritation signs are obvious, subvitreous hemorrhage can be seen in the fundus, and a few may have signs of focal neurological deficits, such as mild hemiparesis, aphasia, and motoneural palsy.
Auxiliary examinations
1, cranial CT: is the preferred method to diagnose SAH, CT shows high-density shadow in the subarachnoid space can confirm the diagnosis of SAH, according to the CT results can initially determine or suggest the location of intracranial aneurysm: if located in the internal carotid artery segment is often asymmetric blood accumulation in the suprasellar pool; middle cerebral artery segment is mostly seen in the lateral fissure accumulation; anterior communicating artery segment is the basal accumulation of blood in the anterior interstitial fissure; and bleeding in the interpeduncular pool and circumferential pool, generally no aneurysm. Dynamic CT examination is also helpful to understand the absorption of hemorrhage, the presence of rebleeding, secondary cerebral infarction, hydrocephalus and its degree, etc.
2. Cerebrospinal fluid (CSF) examination: Usually, lumbar puncture is not used as a routine clinical examination if the diagnosis has been confirmed by CT examination. If the amount of bleeding is small or the time from the onset of the disease is long, CT examination may not have positive findings, but clinical suspicion of subarachnoid hemorrhage requires lumbar puncture to examine CSF. uniform blood cerebrospinal fluid is a characteristic manifestation of subarachnoid hemorrhage and indicates fresh bleeding, such as yellowing of CSF or finding phagocytes that have engulfed erythrocytes, iron-containing heme or bilirubin crystals, etc., it suggests that SAH has existed for different times.
3.Cerebral vascular imaging: It helps to detect abnormal blood vessels in the skull.
(1) Cerebral angiography (DSA): It is the most valuable method to diagnose intracranial aneurysm, with a positive rate of 95%, and can clearly show the location, size, relationship with the aneurysm-carrying artery and the presence of vasospasm. When conditions are available and the condition permits, whole brain DSA should be performed as soon as possible to determine the cause of bleeding, decide the treatment method and judge the prognosis. However, since angiography can aggravate neurological damage, such as cerebral ischemia, aneurysm rupture and bleeding, the timing of angiography should avoid the peak period of cerebral vasospasm and rebleeding, i.e. within 3 days or 3 weeks after bleeding.
(2) CT angiography (CTA) and MR angiography (MRA): they are non-invasive methods of cerebrovascular imaging, mainly used for screening of those with family history of aneurysm or aura of rupture, follow-up of patients with aneurysm and patients who cannot tolerate DSA examination in the acute period.
4. Laboratory tests: routine blood cell analysis, coagulation items, biochemistry and other related tests in emergency.
Diagnostic basis
Clinical diagnosis mainly relies on typical medical history, physical system examination and imaging evidence.
Differential diagnosis
1, traumatic subarachnoid emergence, the main point of differentiation is the presence of a clear history of trauma.
Treatment principles
(A) General management and symptomatic treatment
1.Keep the vital signs stable: after the diagnosis of SAH, the condition should strive for monitoring treatment, closely monitor the changes of vital signs and neurological signs; keep the airway unobstructed, maintain stable respiratory and circulatory system functions.
2.Lower intracranial pressure: Appropriate restriction of fluid intake, prevention and control of hyponatremia, hyperventilation, etc. can help reduce intracranial pressure. Clinically, dehydrating agents are mainly used, commonly used are mannitol, tachyphylaxis, glycerol fructose or glycerol sodium chloride, and albumin can also be used as appropriate. If the accompanying intracerebral hematoma is large in size, surgery should be performed as soon as possible to remove the hematoma and lower the intracranial pressure to save lives.
3. Correct water and electrolyte balance disorders: pay attention to the balance of fluid intake and output. Appropriate rehydration and sodium supplementation, adjustment of diet and the ratio of crystalloids in intravenous rehydration can effectively prevent hyponatremia. Hypokalemia is also more common and timely correction can avoid causing or aggravating cardiac arrhythmia.
4, symptomatic treatment: sedatives for irritability, analgesics for headache, caution with aspirin and other non-steroidal anti-inflammatory and analgesic drugs that may affect the coagulation function or morphine, dulcolax and other drugs that may affect the respiratory function. In case of epileptic seizures, short-term antiepileptic drugs such as Valium, Carbamazepine or Sodium Valproate can be used.
5, strengthen care: local consultation, bed rest, reduce visitation, avoid sound and light stimulation. Give a high-fiber, high-energy diet, and keep the urine and stool flowing. For those with impaired consciousness, nasogastric tube can be given, careful nasal feeding to prevent asphyxia and aspiration pneumonia. If urinary retention is retained, catheterization should be placed and attention should be paid to prevent urinary tract infection. Take measures to prevent complications such as decubitus ulcers, pulmonary atelectasis and deep vein thrombosis by regular turning, passive movement of limbs and air mattress. If DSA examination confirms that the aneurysm is not caused by intracranial aneurysm, or if the intracranial aneurysm has been surgically clamped or interventionally embolized, and there is no risk of rebleeding, the bed rest time can be shortened appropriately.
(B) Prevention and control of rebleeding
1.Quiet rest: absolute bed rest for 4-6 weeks, sedation and analgesia, avoid exertion and emotional stimulation.
2, regulation of blood pressure: after removing pain and other triggers, if the mean arterial pressure > 125 mmHg or systolic pressure > 180 mmHg, short-acting antihypertensive drugs can be used under blood pressure monitoring to bring down the blood pressure and keep it stable at normal or pre-initiation level. Calcium channel blockers, β-blockers or ACEI class can be used.
3.Antifibrinolytic drugs: In order to prevent the clot around the aneurysm from dissolving and causing rebleeding, antifibrinolytic agents can be used to inhibit the formation of fibrinogen. 6-Aminohexanoic acid (EACA) is commonly used, the initial dose of 4-6g dissolved in 100ml of physiological saline or 5% glucose in an IV drip (15-30 minutes), and then generally maintained in an IV drip of 1g/h, 12-24g/d for 2-3 weeks or until surgery, or hemostatic aromatic acid (PAMBA) or hemostatic cyclic acid (tranexamic acid). Antifibrinolytic therapy can reduce the incidence of rebleeding, but it also increases the incidence of CVS and cerebral infarction, and is recommended to be used simultaneously with calcium channel blockers.
4.Surgery: In aneurysmal SAH, if the Hunt and Hess grades are ≤Ⅲ, early surgical clamping of the aneurysm or interventional embolization should be performed.
(C) Prevention and treatment of cerebral artery spasm and cerebral ischemia
1.Maintain normal blood pressure and blood volume: give antihypertensive treatment for high blood pressure; if blood pressure is low after aneurysm treatment, firstly, remove the cause such as reducing or stopping dehydration and antihypertensive drugs; give colloidal solution (albumin, plasma, etc.) to expand and raise blood pressure; if necessary, use antihypertensive drugs such as dopamine drip.
2, early use of nimodipine: commonly used dose 10-20mg/d, intravenous drip 1mg/h for 10-14 days, pay attention to its hypotensive side effects.
3, lumbar puncture to put CSF or CSF replacement: these methods have been applied for many years, but there is a lack of multicenter, randomized, controlled studies. Cerebrospinal fluid replacement at an early stage (1 to 3 days after onset) may be beneficial in preventing cerebral vasospasm and reducing sequelae. Patients with severe signs of meningeal irritation such as severe headache and irritability may be considered for appropriate CSF or CSF replacement therapy, as appropriate. Note the risk of inducing intracranial infection, rebleeding and brain herniation.
(D) Prevention and treatment of hydrocephalus
1, drug therapy: mild acute and chronic hydrocephalus should be preceded by drug therapy, giving drugs such as acetazolamide to reduce CSF secretion, mannitol, tachyphylaxis, etc., as appropriate.
2.Ventricular puncture CSF drainage: CSF drainage is suitable for those who have acute hydrocephalus with progressive increase of symptoms after SAH and medical treatment, or those who cannot tolerate craniotomy because of old age, serious dysfunction of heart, lung and kidney. Emergency ventricular puncture external drainage can reduce intracranial pressure, improve cerebrospinal fluid circulation, reduce the occurrence of obstructive hydrocephalus and cerebral vasospasm, which can improve clinical symptoms in 50% to 80% of patients, and clip the aneurysm as soon as possible after drainage. external drainage of CSF can be used in combination with CSF replacement.
3, CSF shunt: most of the chronic hydrocephalus can be reversed by medical treatment. If medical treatment is ineffective or the effect of external drainage of CSF in the ventricles is not good, and the ventricles are obviously enlarged by CT or MRI, ventricular-atrial or ventricular-abdominal shunt should be performed in time to prevent aggravation of brain damage.
(E) Treatment of diseased vessels
1.Interventional treatment: Interventional treatment does not require craniotomy and general anesthesia, and has little effect on circulation, so it has been widely used in the treatment of intracranial aneurysm in recent years. Before surgery, blood pressure should be controlled, nimodipine should be used to prevent vasospasm, DSA examination should be performed to determine the location and size of the aneurysm, and embolization materials should be selected to perform aneurysm embolization or occlusion of the aneurysm-carrying artery. Intracranial arteriovenous malformation (AVM) can also be occluded by interventional treatment if there are indications.
2.Surgery: It is recommended that patients in good clinical condition (Hunt & Hess grade I, II, III) should be operated as soon as possible (preferably within 3 days or 3 weeks after the onset of the disease). The site of the aneurysm, the aneurysm causing bleeding, and the patient’s clinical classification need to be clarified. Patients who have an aneurysm that is operable and have no medical disease affecting the operation and who are in good clinical condition (Hunt & Hess classification I, II, III) should be operated as soon as possible (preferably within 24 hours of admission). For cases not suitable for surgery, endovascular treatment can be considered. patients with hydrocephalus of Hunt & Hess classification grade IV and V require emergency ventricular drainage. Patients with intracerebral hematoma grade IV and V should have surgical removal of the hematoma and emergency clamping of the aneurysm to save life. The prognosis will be worse for such patients with surgical treatment of the source of hemorrhage. If there is severe vasospasm with infarction, surgery should be postponed.
3.Stereotactic radiotherapy (γ-knife treatment): mainly used for small AVM and the treatment of residual lesions after embolization or surgical treatment.