Analyzing case studies basis anatomical or physiological anomalies

Question

Task: Case study A: A 48-year-old man complains of swelling of the neck and shortness of breath of 1-week duration. He has noticed some nasal stuffiness with hoarseness of his voice for about 3 weeks and had attributed these symptoms to an upper respiratory infection. He denies the use of alcohol but has smoked two packs of cigarettes per day for 30 years. Lately, he feels as though something is pushing against his throat. On physical examination, the patient’s left pupil is constricted and the eyelid is drooping. His face appears ruddy and swollen and the skin is dry. The jugular veins are distended. He is diagnosed with superior vena cava (SVC) syndrome.

1. Outline the function and location of the superior vena cava. 2. Describe the boundaries and contents of the superior mediastinum. 3. Explain SVC syndrome and its causes. 4. Based on this man’s symptoms, what is the most likely cause of his diagnosis? 5. Based on the patient’s group of symptoms, outline the other anatomical structures that are most likely involved. 6. Explain why the man has a hoarse voice. 7. Outline the cause of the dry facial skin, constricted pupil and drooping eyelid. Case study B: A 60-year-old mother of four, visited her family doctor complaining of back pain and the sensation of something ‘coming down’ her vagina, especially when she was standing. In addition, she was troubled by stress incontinence when she coughed, sneezed, or lifted a heavy object, and by the need to urinate up to ten times per day and five times each night. Pelvic examination revealed a first degree uterine prolapse (the cervix was still inside the vagina) and prolapse of the bladder base. The physician referred the woman to a gynaecologist, who recommended surgery. A vaginal hysterectomy and a procedure to correct the prolapse and stress incontinence were performed, relieving the woman of her symptoms.
1. Describe the anatomical support structures in place for the uterus. 2. Explain two main causes of uterine prolapse in women. 3. Briefly outline the other types, and the anatomical mechanism of pelvic organ prolapse in females 4. Describe the structure of the sphincter that controls urinary flow and identify its anatomical location. 5. Describe the mechanism of stress incontinence, and explain why coughing, sneezing, or lifting can cause it.

Answer

Case study 1

1. The superior vena cava (SVC) is a vital component of the circulatory system. As a large vein, it performs the crucial function of transporting deoxygenated blood from the upper body back to the heart (Bonios et al., 2013). This process enables the reoxygenation of the blood in the lungs and circulation throughout the body for supplying oxygen as well as nutrients to the cells. The SVC has several characteristics and connections that are important to understand:

• Formation: The SVC is through the union of the left and right brachiocephalic veins, which in turn are developed by the convergence of the internal jugular and subclavian veins on each side. The blood is collected from the head, neck, and upper limbs through these veins

• Azygos vein: The azygos vein is a significant tributary of the SVC that drains blood from the posterior walls of the thorax and abdomen. It also serves as a collateral pathway for blood return to the heart if the inferior vena cava (IVC) or SVC becomes obstructed (Bonios et al., 2013).

• Venous drainage: In addition to the brachiocephalic veins and the azygos vein, the SVC receives drainage from several smaller veins, such as the pericardial veins, thymic veins, and mediastinal veins. These veins collect blood from structures in the thoracic cavity and surrounding tissues.

• Relationship to surrounding structures: The SVC is closely related to various structures within the superior mediastinum, such as the trachea, esophagus, aortic arch, thymus, and numerous nerves and lymph nodes. Understanding these relationships is essential in diagnosing and treating various medical conditions that can affect the mediastinum.

• SVC obstruction: Obstruction of the SVC can lead to a range of symptoms, such as facial swelling, neck swelling, and upper limb swelling, which can result from various causes, including malignancies, infections, and blood clots (Bonios et al., 2013). Superior vena cava syndrome is a medical emergency characterized by the compression or obstruction of the SVC, leading to reduced blood flow and the accumulation of blood in the veins of the upper body.

2. The superior mediastinum is the upper portion of the mediastinum, which is the space between the lungs in the thoracic cavity (Shebli et al., 2020). Its boundaries are the thoracic inlet superiorly, the transverse thoracic plane (T4/T5 vertebral level) inferiorly, the sternum anteriorly, and the thoracic vertebrae posteriorly. The contents of the superior mediastinum include the SVC, aortic arch and its branches, trachea, esophagus, thymus, phrenic nerves, vagus nerves, and various lymph nodes.

3. Superior vena cava syndrome (SVCS) is a medical emergency characterized by the obstruction or compression of the SVC, leading to reduced blood flow and the accumulation of blood in the veins of the upper body. It leads to swelling, congestion, and other symptoms in the head, neck, and upper extremities. Common causes of SVCS include malignancies (e.g., lung cancer, lymphoma), infections, blood clots, and certain autoimmune diseases (Kloesel & Lekowski 2016).

4. In this patient, the expected cause of the SVC syndrome is a malignancy, particularly lung cancer. It happens due to significant smoking history (two packs of cigarettes per day for 30 years), constituting as a major risk factor for lung cancer. Lung cancer can cause compression of the SVC, leading to the symptoms described (Shebli et al., 2020).

5. The patient's group of symptoms, including facial swelling, jugular vein distention, nasal stuffiness, hoarseness, and the involvement of the left pupil and eyelid, suggest that other anatomical structures in the mediastinum are likely involved. These structures may include the recurrent laryngeal nerve (hoarseness), the sympathetic chain (Horner's syndrome: constricted pupil, drooping eyelid), and the lymphatic system (facial swelling, jugular vein distention).

6. The vagus nerve has a branch known as the recurrent laryngeal nerve (RLN) that is responsible for regulating the muscles in the voice box or larynx (Bai & Chen 2018). The RLN offers motor innervation to all the larynx intrinsic muscles, excluding the muscle of cricothyroid, and even provides innervations of sensorynature to the larynx situated below the vocal cords (Kloesel & Lekowski 2016). In the case of the man with SVC syndrome, the compression or obstruction of the SVC may lead to an increase in pressure in the superior mediastinum. This can cause compression or irritation of the RLN, which runs in close proximity to the SVC. When the RLN is impacted, it leads to vocal cords dysfunction that can lead to hoarseness or even vocal paralysis. This is because the muscles of the larynx are unable to move correctly or coordinate effectively, leading to changes in vocal quality and pitch.

The involvement of the RLN can be caused by various factors, including tumors, enlarged lymph nodes, or other structures compressing the nerve. In SVC syndrome, the pressure caused by the obstruction or compression of the SVC may lead to swelling or inflammation of the surrounding tissues, causing the RLN to become compressed or irritated.

Hoarseness is a common symptom associated with SVC syndrome, and it is important to identify the underlying cause to provide appropriate treatment. If RLN involvement is suspected, additional diagnostic tests such as laryngoscopy or imaging studies may be necessary to determine the extent of nerve damage (Simsek et al., 2016). Treatment options may include addressing the underlying cause of SVC syndrome, such as radiation or chemotherapy for cancer, or surgical interventions to relieve the pressure on the nerve. In some cases, speech therapy may also be helpful in improving vocal quality and reducing hoarseness.

7. The cause of the patient's dry facial skin, pupil constricted, and eyelid drooping can be explained through syndrome of Horner's, which is caused by disruption of the sympathetic nerve pathway. In this case, the lung tumor or enlarged lymph nodes may be compressing or damaging the sympathetic chain in the mediastinum. This results in a loss of sympathetic tone, leading to the characteristic symptoms of Horner's syndrome: ptosis (drooping eyelid), miosis (pupil constricted), and anhidrosis (lack of sweating and hence, dry skin).

In summary, SVC syndrome is a severe condition that results from the obstruction or compression of the superior vena cava. In this patient, the most likely cause is a lung malignancy due to his significant smoking history. His symptoms suggest involvement of other anatomical structures in the mediastinum, such as the recurrent laryngeal nerve and the sympathetic chain. Prompt diagnosis and treatment are crucial to relieve the obstruction and manage the underlying cause

Case Study 2

1. The uterus which lies in the pelvis is a muscular organ which is pear-shape and supported by several anatomical structures. These structures comprise of the pelvic floor muscles that form a hammock-like structure and supports the uterus, bladder, and rectum. The uterosacral ligaments attach the cervix to the sacrum, providing posterior support to the uterus. The cardinal ligaments provide lateral support to the uterus, attaching it to the pelvic sidewall (Zhao et al., 2017). The round ligaments offer front support as they extend from the uterus through the inguinal canals to the labia majora.

2. Uterine prolapse occurs when the uterus descends from its normal position in the pelvis and protrudes into the vagina. Two main causes of uterine prolapse are weakened pelvic support structures and increased intra-abdominal pressure. Weakened pelvic support structures can result from multiple pregnancies, vaginal childbirth, menopause, obesity, aging, and connective tissue disorders. Higher pressure within the abdominal cavity may occur due to actions like lifting heavy objects, persistent coughing, and pushing excessively while passing stools.

3. Pelvic organ prolapse refers to the situation where one or multiple organs in the pelvic region, like the bladder, uterus, vagina, or rectum, move downwards from their usual location and bulge into the vaginal canal (Khadzhieva et al., 2017).

There are four main types of pelvic organ prolapse:

• Cystocele: bladder Prolapse into the anterior vaginal wall

• Rectocele: Prolapse of the rectum into the posterior vaginal wall

• Enterocele: Prolapse of the small intestine into the vaginal vault

• Vaginal vault prolapse: Prolapse of the upper portion of the vagina

Pelvic organ prolapse can occur due to weakened pelvic support structures, increased intra-abdominal pressure, hormonal changes, chronic coughing, straining during bowel movements, and connective tissue disorders. The passage of urine from the bladder to the urethra is controlled by a muscular structure located at the bladder outlet called the urinary sphincter. This sphincter is made up of two muscle groups, the internal urethral sphincter, and the external urethral sphincter.

The internal urethral sphincter can be defined as an involuntary smooth muscle that contracts to prevent urine flow. The external urethral sphincter is a voluntary skeletal muscle that encircles the urethra and can be consciously contracted to prevent urine leakage. Stress incontinence arises when urine is unintentionally released in times of activities that cause elevated abdominal pressure, such as coughing, sneezing, laughing, or lifting. This condition is caused by weakened pelvic floor muscles and/or damaged sphincter mechanisms. When the pelvic floor muscles weaken, the urethra may move downward, causing a change in the angle between the bladder and urethra. This can result in decreased urethral closure pressure and an increased risk of urine leakage during activities that enahnces abdominal pressure. Additionally, damage to the external urethral sphincter can also lead to stress incontinence. When the sphincter is weakened or damaged, it cannot maintain adequate urethral closure pressure, resulting in leakage of urine due to activities that put pressure on the abdomen.

4. The bladder outlet contains a sphincter that is responsible for urine flow regulation, comprising of two primary muscle groups: the internal urethral sphincter and the external urethral sphincter. Present at the bladder base, the internal urethral sphincter is an involuntary smooth muscle that encircles the urethra, providing crucial baseline closure pressure. This pressure helps in the prevention of urine leakage. The external urethral sphincter is a voluntary skeletal muscle that stays below the internal sphincter and surrounds the surrounding the urethra when it passes through the pelvic floor muscles. This muscle can be consciously contracted to increase the closure pressure of the urethra and prevent urine leakage.

5. Stress incontinence is a type of urinary incontinence that occurs when loss of urine happens involuntarily during activities that leads to an increase in the abdominal pressure like sneezing, coughing or lifting. It happens due to a weakened pelvic floor muscle and/or external urethral sphincter damage. The weakening of pelvic floor muscles results in insufficient support to the bladder and urethra. The urethra downward movement because of weakening of pelvic floor muscles leads to a change in the angle between the bladder and urethra (Robinson & Cardozowan 2014). This shift can lead to a decrease in urethral closure pressure, which is necessary to prevent urine leakage. Apart from the weakening of the pelvic floor muscles, damage to the external urethral sphincter can also be a great addition to the stress incontinence. When the external sphincter is weakened or damaged, it cannot provide adequate urethral closure pressure, leading to urine leakage during activities that leads to an increment in the abdominal pressure.

Coughing, sneezing, or lifting can cause stress incontinence because these activities increase intra-abdominal pressure, which can exceed the closure pressure of the weakened pelvic floor muscles and/or sphincter mechanisms. Urine leakage happens when there is an enhanced pressure on the bladder and urethra which cause a shift

Stress incontinence treatment might include exercises of pelvic floor muscle, behavioral modifications, such as weight loss, and surgical interventions, such as bladder neck suspension or sling procedures, which aim to restore the pelvic floor muscles' support or improve the external urethral sphincter's function.

References

Bai, B., & Chen, W. (2018). Protective effects of intraoperative nerve monitoring (IONM) for recurrent laryngeal nerve injury in thyroidectomy: Meta-analysis. Scientific Reports (Nature Publisher Group), 8, 1-11. doi:https://doi.org/10.1038/s41598-018-26219-5

Bonios, M. J., Anastasiadis, G., Vlachodimitris, I., & Ekonomou, C. (2013). Persistent left superior vena cava with absent right superior vena cava. Hospital Chronicles, 8(3), 140-142. Retrieved from https://www.proquest.com/scholarly-journals/persistent-left-superior-vena-cava-with-absent/docview/1689936421/se-2

Robinson, D., & Cardozowan, L. (2014). Urinary incontinence in the young woman: Treatment plans and options available. Women's Health, 10(2), 201-17. doi:https://doi.org/10.2217/whe.14.1

Shebli, B., Alzahran, A., Mansour, A., Kabaweh, S., Agha, S., Shareef, B., & Abdullah, M. (2020). Mitral regurgitation due to a mediastinal desmoid tumor: A case report and review of the literature. Clinical Case Reports, 8(12), 2457-2463. doi:https://doi.org/10.1002/ccr3.3181

Kloesel, B., & Lekowski, R. W. (2016). Complex perioperative decision-making: Liver resection in a patient with extensive superior vena Cava/Right atrial thrombus and superior vena cava syndrome. Case Reports in Anesthesiology, 2016 doi:https://doi.org/10.1155/2016/2106242

Khadzhieva, M. B., Kolobkov, D. S., Kamoeva, S. V., & Salnikova, L. E. (2017). Expression changes in pelvic organ prolapse: A systematic review and 0RW1S34RfeSDcfkexd09rT2in silico1RW1S34RfeSDcfkexd09rT2 study. Scientific Reports (Nature Publisher Group), 7, 1-11. doi:https://doi.org/10.1038/s41598-017-08185-6

Simsek, G., M.D., Akin, I., M.D., Saka, C., M.D., & Koybasioglu, F., M.D. (2016). Thymoma with an incidental benign laryngeal mass mimicking laryngeal carcinoma: Case report. Ear, Nose & Throat Journal, 95(2), 68-69,80. Retrieved from https://www.proquest.com/scholarly-journals/thymoma-with-incidental-benign-laryngeal-mass/docview/1774180445/se-2

Zhao, X., Ma, C., Li, R., Xue, J., Liu, L., & Liu, P. (2017). Hypoxia induces apoptosis through HIF-1? signaling pathway in human uterosacral ligaments of pelvic organ prolapse. BioMed Research International, 2017, 8. doi:https://doi.org/10.1155/2017/8316094