Fifty-four-year-old Fred is complaining of a headache that started about 2 weeks ago. For the past 2 days, the headache has increased in severity, and he is photophobic and has nuchal rigidity and projectile vomiting. CT scan results show an arteriovenous malformation in the basal artery and a small hemorrhagic bleed in the middle meningeal artery.
1. How is the concept of “disorders of brain function” related to Fred’s presenting symptoms?
2. What aspects of cerebral circulation would come into play in Fred’s case?

Leonore post

• How is the concept of “disorders of brain function” related to Fred’s presenting symptoms?

Fred likely has an arterio-vascular malformation. This is likely a related to a defect that occurred during the embryonic prenatal period. The capillary and venous network fails to develop properly, and collateral arterial circulation develops, and the blood gets shunted from the arterial (high-pressure blood flow) to the venous system (less-pressure blood flow). This usually occurs before age 40, symptoms can begin as early as age 10 and get progressively worse over time. Risk is statistically similar in men and women, although men have a slightly higher risk of AVM. Knowing family history is important as well, there might be some correlation but at this time it is uncertain if this is a genetically transferred disorder. Fred suffered from an unusual headache for two weeks that worsened over time this is a usual sign that occurs prior to an aneurysm as well. Nausea, sensitivity to light, and stiff neck is likely relate to worsening of the aneurysm. Fred should have gone to the doctor when his headache was not relieved by over the counter analgesics or if he suffered from migraine symptoms during his lifetime and had medication that was not relieving his headache. (Norris & Tuan, 2019)(Natali et al., 2020)

• What aspects of cerebral circulation would come into play in Fred’s case?

During the embryonic period the development of capillary network is fails to develop. This causes the pressure in the venous system to increase, this increases the arterial blood pressure as well this can lead to rupture and hemorrhage. The brain is affected by a lack of oxygenated blood. This again is related to the fact that the blood bypasses the underdeveloped capillary network. The high-pressure blood flow not slowed by the small blood vessels flows directly from the arteries to veins. The brain tissue is unable to absorb the oxygen from the highly pressurized blood flow and the tissue gets weaker or apoptosis of the tissue occurs. This can cause symptoms, such as speech problems, visual loss, unsteadiness related to numbness and weakness. Thinned blood vessels become weak and the bulging area (aneurysm) are susceptible to rupture. (Mayo Clinic Staff, n.d.) The middle meningeal artery can originate from multiple areas in the brain and if Fred should have surgery prior to having a stroke, the neuro surgeon needs to be aware of the location, though an extremely successful intervention, as the middle meningeal artery may originate in different areas of the brain for example next to the internal carotid artery, posterior to the cerebellar artery. That is why imaging prior to the surgery imaging is extremely important. (Natali et al., 2020)
References
Mayo Clinic Staff. (n.d.). Retrieved August 5, 2020, from Https://www.mayoclinic.org/diseases-conditions/brain-avm/symptoms-causes/syc-20350260
Natali, A. L., Reddy, V., & Leo, J. T. (2020, April 15). Neuroanatomy, Middle Meingeal Arteries [StatPearls (Internet)]. NCBI. Retrieved August 4, 2020, from https://www.ncbi.nlm.nih.gov/books/NBK519545/
Norris, T. L., DNS, RN, & Tuan, R. L., PhD. (2019). Porth’s Pathophysiology Concepts of Altered Health States (Tenth ed.). Wolters Kluwer.

Mary post
Question 1
Understanding the normal brain anatomy and physiology is paramount to integrating the presenting signs and symptoms to form an accurate diagnosis. According to Huether and McCance (2016), there are numerous disorders of the brain function and most of the time the presenting signs and symptoms are similar. Brain function disorders refer to any condition or disability that affect the brain. An in-depth understanding of the pathophysiology of each disorder is required for one to establish an accurate diagnosis (Huether & McCance, 2016). The presenting signs and symptoms help one in eliminating inapplicable differential diagnoses by giving clues on the specific areas of the brain that are affected. Comprehending pathophysiology helps a nurse to lay the foundation upon which his/her responsibilities will involve. This includes ordering tests for diagnosis, treatment of illnesses, management of medications, disease complication prevention and maintenance of general health.
In this case, the presenting sign of uncial rigidity denotes increased intracranial pressure. This could be a result of many conditions, including hemorrhage, and the CT scan has revealed there to a small hemorrhagic bleed in the middle meningeal artery. Photophobia is a common presenting symptom in severe headaches. In a study conducted in Croatia in 2014, up to 40% patients who experienced headaches also had photophobia (Cvetković et al., 2014). Photophobia is a neurologic symptom that denotes the affected areas of the brain such as trigeminal nerve pathway and the thalamus region. Projectile vomiting is often seen in conditions involving cerebral hemorrhage. This is because the neural pathway that triggers vomiting via the chemoreceptor trigger zone beneath the brainstem, is triggered. Injury to areas near the brainstem would trigger the chemoreceptor zone which induces projectile vomiting (Huether & McCance, 2016). Knowledge on disorders brain function is useful in relating how the results of the CT scan are connected to the signs and symptoms. Arteriovenous malformations can rapture if there is increased intracranial pressure, thereby leading to other subsequent symptoms of head injury.
Question 2
Changes in blood pressure circulating in the brain as a result of hemorrhage, significantly affects the cerebral circulation and perfusion. The physiological changes that occur as a result of a hemorrhage help in autoregulating the blood flow in an effort to make it normal. The processes involved are a reflex and interplay with each other to maintain sufficient perfusion (Salinet, Panerai & Robinson, 2014). Hemorrhage leads to increased intracranial pressure which affects brain function by reducing cerebral blood flow. Increased ICP causes reduced cerebral blood flow by compressing cerebral arteries thus limiting blood flow and causing an increase in the cerebrovascular resistance.
Additionally, the increased intracranial pressure causes the hydrostatic pressure within the interstitial space to increase thereby reducing filtration that takes place in the intracerebral blood vessels. As a result of hemorrhage and increased intracranial pressure, decreased cerebral blood perfusion occurs in the brain cells. Another consequence of hemorrhage and increased intracranial pressure is an increase in cerebral perfusion pressure. Consequently, this can worsen the hemorrhage that already exists due to additional forces. Changes in perfusion and the consequences such as ischemia, happen quickly (Salinet, Panerai & Robinson, 2014). Therefore, prompt fluid management is required. Caution should be taken to avoid intravenous fluids that increase intracranial pressure because they will worsen the existing condition.

References
Cvetković, V. V., Plavec, D., Lovrenčić-Huzjan, A., Strineka, M., Ažman, D., & Bene, R. (2014). Prevalence and clinical characteristics of headache in adolescents: a Croatian epidemiological study. Cephalalgia, 34(4), 289-297.
Huether, S. E., & McCance, K. L. (2016). Study Guide for Understanding Pathophysiology-E-Book. Elsevier Health Sciences.
Salinet, A. S., Panerai, R. B., & Robinson, T. G. (2014). The longitudinal evolution of cerebral blood flow regulation after acute ischaemic stroke. Cerebrovascular diseases extra, 4(2), 186-197.