DRG Category: 27
Mean LOS: 2.6 days
Description: Surgical: Craniotomy and Endovascular Intracranial Procedures Without Complication or Comorbidity or Major Complication or Comorbidity
DRG Category: 70
Mean LOS: 6.2 days
Description: Medical: Nonspecific Cerebrovascular Disorders With Major Complication or Comorbidity
Cerebral aneurysm is a potentially devastating condition that may lead to life-threatening consequences. Cerebral aneurysm is an outpouching of the wall of a cerebral artery that results from weakening of the wall of the vessel. It is difficult to determine the frequency of cerebral aneurysms because of differences in the definitions of the size of aneurysm and the ways that aneurysms are detected. The prevalence is estimated to range from 5% to 10%; unruptured aneurysms account for approximately 50% of all aneurysms.
Cerebral aneurysms have a variety of sizes, shapes, and causes (Table 1). Most cerebral aneurysms are sacular or berrylike with a stem and a neck. The incidence of cerebral aneurysm has been estimated at 12 cases per 100,000 individuals, with approximately 15% to 25% of patients having multiple aneurysms, often bilaterally in the same location on both sides of the head. Clinical concern arises if an aneurysm ruptures or becomes large enough to exert pressure on surrounding structures. When the vessel wall becomes so thin that it can no longer withstand the surrounding arterial pressure, the cerebral aneurysm ruptures, causing direct hemorrhaging of arterial blood into the subarachnoid space (subarachnoid hemorrhage [SAH]). SAH is a life-threatening situation with a mortality rate of up to 65%.
Table 1 Classification of Cerebral Aneurysms
| Size | Small, < 15 mm | | Large, 15–25 mm | | Giant, 25–50 mm | | Supergiant, 50 mm | Shape | Berry: Most common (95%); berry-shaped aneurysm with a neck or stem | | Sacular: Any aneurysm with a sacular outpouching | | Fusiform: Outpouching of an arterial wall but with no stem | Etiology | Traumatic: Aneurysm that results from traumatic (penetrating or closed) head injury | | Charcot-Bouchard: Microscopic aneurysmal formation associated with hypertension; involves the basal ganglia and brainstem | | Dissecting: Related to atherosclerosis, inflammation, or trauma; aneurysm in which the intimal layer is pulled away from the medial layer and blood is forced between the layers |
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Complications of a ruptured cerebral aneurysm can be fatal if bleeding is excessive. SAH can lead to cerebral vasospasm, cerebral infarction, and death. Rebleeding often occurs in the first 48 hours after the initial bleed but can occur any time within the first 6 months. Other complications include meningeal irritation and hydrocephalus.
Possible causes are congenital structural defects in the inner muscular or elastic layer of the vessel wall; incomplete involution of embryonic vessels; and secondary factors such as arterial hypertension, atherosclerotic changes, hemodynamic disturbances, and polycystic disease. Cerebral aneurysms also may be caused by shearing forces during traumatic head injuries. Associated conditions are arteriovenous malformations, coarctation of the aorta, systemic lupus erythematosus, sickle cell anemia, bacterial endocarditis, and fungal infections. Cigarette smoking and alcohol and drug use and misuse have been linked to cerebral aneurysms.
Susceptibility to cerebral aneurysm appears to have a genetic component, as individuals with two or more affected family members have a three- to sixfold higher incidence of cerebral aneurysm. Researchers have identified over two dozen variants that may confer susceptibility, but very few specific genes have been identified. The most well replicated is a variant on chromosome 9 near the cyclin-dependent kinase inhibitor genes CDKN2A and CDKN2B. Other genes that have been associated with aneurysms include perlecan, elastin, collagen I and II, nitric oxide synthase, and endothelin receptor A. There are also rare familial forms of cerebral aneurysm susceptibility, which have unclear patterns of inheritance. In one study of familial inheritance patterns, the autosomal recessive pattern was seen in slightly more than half of the population, and autosomal dominance was seen in just over one-third, with about 5% showing incomplete penetrance. The autosomal dominant disorder polycystic kidney disease has been associated with an increased incidence of intracerebral aneurysm. Other genetic conditions associated with connective tissue disorders have also been associated with increased risk of aneurysms, including neurofibromatosis, Marfan syndrome, multiple endocrine neoplasia, Ehlers-Danlos syndrome, and hereditary hemorrhagic telangiectasia.
The peak incidence of cerebral aneurysm occurs between ages 35 and 60 years. Women in their late 40s through mid-50s are affected slightly more than men. Early age of menopause is associated with the presence of cerebral aneurysm, possibly because of the earlier loss of estrogen. The prognosis of SAH resulting from an aneurysm is worse for women than for men. Cerebral aneurysms rarely occur in children and adolescents, but when they occur, they are often larger than those found in adults; pediatric aneurysms account for approximately 2% of all cerebral aneurysms.
The odds of Black persons having a cerebral aneurysm are approximately twice that of White persons. Black, Hispanic, and uninsured persons are more likely to arrive at the hospital with an aneurysmal subarachnoid hemorrhage (ruptured aneurysm), whereas White persons are more likely to arrive at the hospital with an unruptured aneurysm. Experts suggest that this difference occurs because of reduced access to healthcare by Black, Hispanic, and uninsured persons (Rinaldo et al., 2019).
Transgender is a term used to describe persons whose gender identity is different from their sex assigned at birth. Approximately 1% of the U.S. population identify themselves as transgender. Sexual and gender minority persons have higher odds for multiple chronic conditions, cancer, and poor quality of life and are more apt to have disabilities than cisgender males and females (cisgender is a term used to describe persons whose gender identity and gender expression are aligned with their assigned sex listed on their birth certificate). Gender-affirming hormone therapy is the use of hormone therapy for gender transition or gender affirmation and can be masculinizing or feminizing. It may also affect cardiovascular health in transgender females. In a large sample, researchers have found that transgender men and women are more likely to be overweight than cisgender women. Compared to cisgender women, transgender women reported higher rates of diabetes, ischemic stroke, angina/coronary disease, and myocardial infarction. Gender-nonconforming men and women reported higher odds of myocardial infarction than cisgender women. Transgender women also had higher rates of any cardiovascular disease than cisgender men (Cacerese, Jackman, et al., 2020; Connelly et al., 2019). While large-scale studies are not available, these factors may place some sexual and gender minorities at risk for cerebral aneurysm.
The estimated frequency of cerebral aneurysm globally is approximately 10 (a range of 4–20) per 100,000 individuals, but it is dependent on location. The highest rates are reported in Japan, China, Sweden, and Finland.
PLANNING AND IMPLEMENTATION
Collaborative
The first priority is to evaluate and support airway, breathing, and circulation. For patients unable to maintain these functions independently, assist with endotracheal intubation, ventilation, and oxygenation, as prescribed. Monitor neurological status carefully every hour and immediately notify the physician of any changes in the patient's condition.
The management of unruptured cerebral aneurysms is controversial. If there is no history of SAH, aneurysms of less than 10 mm in size have a rupture rate of less than 1% per year. Recent guidelines by expert panels and professional organizations have developed recommendations based on the patient's age, history, and aneurysm size. The choice of surgery versus medical management depends on these parameters as well as on the surgeon's expertise and consideration that mortality rates are 4% and morbidity rates are 16% after surgery. Microsurgery may be used to prevent rupture or rebleeding of the cerebral artery. The decision to operate depends on the clinical status of the patient, including the level of consciousness and severity of neurological dysfunction, the accessibility of the aneurysm to surgical intervention, the skill of the surgeon, and the presence of vasospasm. Surgical procedures used to treat cerebral aneurysms include direct clipping or ligation of the neck of the aneurysm to enable circulation to bypass the pathology. Endovascular coiling of cerebral aneurysms is a minimally invasive technique that may be used in aneurysms with a small neck size (< 4 mm), a luminal diameter < 25 mm, and those that are distinct from the parent vessel. An inoperable cerebral aneurysm may be reinforced by applying acrylic resins or other plastics to the sac. Postoperatively, monitor the patient closely for signs and symptoms of increasing ICP or bleeding, such as headache, unequal pupils or pupil enlargement, onset or worsening of sensory or motor deficits, or speech alterations.
| Medication or Drug Class | Dosage | Description | Rationale |
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| Calcium channel blockers | Varies with drugs such as nimodipine, verapamil | Inhibit calcium entry across cell membranes in vascular smooth muscles | Prevent vasospasm and hypertension |
| Morphine sulfate | 5–10 mg IV prn | Opioid analgesic | Drug of choice for pain relief because of reliable effects and ease of reversibility with naloxone |
Other Drugs: Antihypertensives such as labetalol may be prescribed for patients with high blood pressure. Antiepileptics such as fosphenytoin are administered for treatment and prevention of seizures. Sedatives may be prescribed to promote rest and relaxation, and aminocaproic acid, a fibrinolytic inhibitor, may be given to minimize the risk of rebleeding by delaying blood clot lysis. The patient may receive colloids such as albumin or plasmanate to decrease blood viscosity and expand the intravascular volume.
Independent
The environment should be as quiet as possible, with minimal physiological and psychological stress. Maintain the patient on bedrest. Limit visitors to immediate family and significant others. Apply thigh-high elastic stockings and intermittent external compression boots. Discourage and control any measure that initiates Valsalva maneuver, such as coughing, straining at stool, pushing up in bed with the elbows, and turning with the mouth closed. Assist with hygienic care as necessary. If the patient has a facial weakness, assist them during meals.
Preoperatively, provide teaching and emotional support for the patient and family. Position the patient to maintain a patent airway by elevating the head of the bed 30 to 45 degrees to promote pulmonary drainage and limit upper airway obstruction. Suction the patient's mouth and, if needed, the nasopharynx and trachea. Before suctioning, oxygenate the patient well, and to minimize ICP increases, limit suctioning to 20 to 30 seconds at a time. If the patient has facial nerve palsy, apply artificial tears to both eyes. Take appropriate measures to prevent skin breakdown from immobility. Postoperatively, promote venous drainage by elevating the head of the bed 20 to 30 degrees. Emotional support of the patient and family is also important. The patient may be dealing with a neurological deficit, such as paralysis on one side of the body or loss of speech. If the patient cannot speak, establish a simple means of communication such as using a slate to write messages or using cards. Encourage the patient to verbalize fears of dependency and of becoming a burden.
Evidence-Based Practice and Health Policy
Wang, A., Campos, J., Colby, G., Coon, A., & Lin, L. (2020). Cerebral aneurysm treatment trends in National Inpatient Sample 2007–2016: Endovascular therapies favored over surgery. Journal of NeuroInterventional Surgery, 12, 957–963.
- The authors studied changes in aneurysm treatment practice patterns in the United States because flow modulation is a new endovascular technique for treatment of cerebral aneurysms as compared to open surgical approaches. Using the National Inpatient Sample Databases (2007–2016), the authors researched patient demographics, hospital characteristics, and clinical outcomes for hospital discharges. They studied patients with unruptured aneurysms (UA), ruptured aneurysms (RA), and/or treatments that included surgical clipping (SC) and/or endovascular treatments (EVT) using the International Classification of Diseases Codes. They also performed 5-year subgroup analyses for treatment differences.
- A total of 39,382 hospital discharges were identified with a significant increase in endovascular techniques over time. Hospitals in the South demonstrated the most significant EVT use. The 5-year subgroup analyses showed that although there was no significant difference in the mean number of cases for the two treatment modalities in the 2007–2011 subgroup, the 2012–2016 subgroup showed that significantly more UA and RA received EVT. The findings illustrated that the standard of care for treatment of cerebral aneurysms is shifting further toward endovascular therapies over open surgical approaches in the United States.