Cyclin-dependent kinase-like 5 (CDKL5) deficiency disorder (CDD) is a rare X-linked neurodevelopmental condition marked by early-onset, refractory seizures and profound developmental delays. The hallmark feature of CDD is epilepsy, typically manifesting within the first few months of life. These seizures are often resistant to standard anti-seizure medications and contribute significantly to the disorder’s morbidity. Genetic
Secretin stimulation testing is a specialized diagnostic procedure used to evaluate pancreatic exocrine function and confirm the presence of gastrin-secreting tumors, such as those seen in Zollinger-Ellison syndrome (ZES). Secretin, a gastrointestinal hormone, plays a critical role in stimulating pancreatic bicarbonate secretion and modulating gastric acid production through its action on G cells and pancreatic
Secondary syphilis is the second stage of the sexually transmitted infection caused by Treponema pallidum, typically occurring weeks to a few months after the initial chancre of primary syphilis heals. It is marked by systemic dissemination of the spirochete, resulting in a wide range of dermatologic, mucosal, and systemic manifestations. Pathogenesis and Transmission The pathogen
Secondary progressive multiple sclerosis (SPMS) is a distinct phase of multiple sclerosis (MS) characterized by a progressive worsening of neurologic function over time. Initially, patients typically experience a relapsing-remitting course (RRMS), which later transitions into SPMS with or without superimposed relapses. Unlike RRMS, the disease in SPMS gradually advances regardless of inflammation, leading to accumulating
Secondary prevention of atherosclerotic cardiovascular disease (ASCVD) refers to a strategic, evidence-based approach to reduce the recurrence of cardiovascular events in individuals with a documented history of coronary artery disease, stroke, or peripheral arterial disease. This involves rigorous control of risk factors, pharmacologic interventions, and lifestyle modifications aimed at mitigating future morbidity and mortality. Clinical
Seasonal allergic rhinitis, commonly referred to as hay fever, is an immunoglobulin E (IgE)-mediated allergic condition characterized by nasal inflammation triggered by seasonal allergens such as pollen from trees, grasses, and weeds. It primarily affects the upper respiratory tract and is one of the most prevalent allergic disorders worldwide. Key Causes and Triggers of Seasonal
Scrub typhus, also known as tsutsugamushi disease, is a potentially fatal mite-borne rickettsial infection caused by Orientia tsutsugamushi. Endemic to the “tsutsugamushi triangle” extending across Southeast Asia, Northern Australia, and the western Pacific, the disease remains a significant public health concern due to its variable presentation and diagnostic challenges. Timely recognition and appropriate antibiotic therapy
Sclerotherapy is a common medical procedure used to treat esophageal varices, particularly in patients with liver cirrhosis. While the procedure is generally effective in controlling variceal bleeding, it can sometimes lead to complications, one of the most significant being sclerotherapy-induced esophageal ulcers. These ulcers can cause severe discomfort and may complicate the patient’s recovery process.
Scleroderma renal crisis (SRC) is an acute, life-threatening complication of systemic sclerosis (scleroderma) characterized by rapid onset of severe hypertension and acute kidney injury. It represents one of the most urgent medical emergencies in scleroderma patients, primarily affecting those with diffuse cutaneous systemic sclerosis. Clinical Presentation and Symptoms of SRC SRC typically presents abruptly and
Scleroderma, also known as systemic sclerosis, is a rare and chronic autoimmune connective tissue disease characterized by hardening and tightening of the skin and connective tissues. In some cases, it also affects internal organs such as the lungs, heart, kidneys, and gastrointestinal tract. The condition arises when the body’s immune system produces excess collagen, leading