NEET MDS Synopsis
Adult Respiratory Distress Syndrome
General Pathology
Adult Respiratory Distress Syndrome
A constellation of pathologic and clinical findings initiated by diffuse injury to alveolar capillaries. This syndrome is associated with a multitude of clinical conditions which primarily damage the lung or secondarily as part of a systemic disorder.
Pathogenesis
There are many types of injuries which lead to the ultimate, common pathway, i.e., damage to the alveolar capillary unit. The initial injury most frequently affects the endothelium, less frequently the alveolar epithelium. Injury produces increased vascular permeability, edema, fibrin-exudation (hyaline membranes). Leukocytes (primarily neutrophils) plays a key role in endothelial damage.
Pathology
Heavy, red lungs showing congestion and edema. The alveoli contain fluid and are lined by hyaline membranes.
Pathophysiology
Severe respiratory insufficiency with dyspnea, cyanosis and hypoxemia refractory to oxygen therapy.
Diphenoxylate
Pharmacology
Diphenoxylate (present in Lomotil)
A meperidine congener
Not absorbed very well at recommended doses.
Very useful in the treatment of diarrhea.
Nephritic syndrome
General Pathology
Nephritic syndrome
Characterized by inflammatory rupture of the glomerular capillaries, leaking blood into the urinary space.
Classic presentation: poststreptococcal glomerulonephritis. It occurs after a group A, β–hemolytic Streptococcus infection (e.g., strep throat.)
Caused by autoantibodies forming immune complexes in the glomerulus.
Clinical manifestations:
oliguria, hematuria, hypertension, edema, and azotemia (increased concentrations of serum urea nitrogen
and creatine).
Classification for antiasthmatic drugs.
Pharmacology
ANTIASTHMATIC AGENTS
Classification for antiasthmatic drugs.
I. Bronchodilators
i. Sympathomimetics (adrenergic receptor agonists)
Adrenaline, ephedrine, isoprenaline, orciprenaline, salbutamol, terbutaline, salmeterol, bambuterol
ii. Methylxanthines (theophylline and its derivatives)
Theophylline
Hydroxyethyl theophylline
Theophylline ethanolate of piperazine
iii. Anticholinergics
Atropine methonitrate
Ipratropium bromide
II. Mast cell stabilizer
Sodium cromoglycate
Ketotifen
III. Corticosteroids
Beclomethasone dipropionate
Beclomethasone (200 µg) with salbutamol
IV. Leukotriene pathway inhibitors
Montelukast
Zafirlukast
Miscellaneous Non-Neoplastic Diseases - Urticaria
General Pathology
Urticaria (hives) refers to the presence of edema within the dermis and itchy elevations of the skin which may relate to either a Type I (MC) or Type III hypersensitivity reaction.
Type III hypersensitivity reaction.
- exaggerated venular permeability MC related to IgE mediated disease and release of histamine from mast cells.
Distoangular Impaction
Oral and Maxillofacial SurgeryDistoangular Impaction
Distoangular impaction refers to the position of a tooth,
typically a third molar (wisdom tooth), that is angled towards the back of the
mouth and the distal aspect of the mandible. This type of impaction is often
considered one of the most challenging to manage surgically due to its
orientation and the anatomical considerations involved in its removal.
Characteristics of Distoangular Impaction
Pathway of Delivery:
The distoangular position of the tooth means that it is situated in
a way that complicates its removal. The pathway for extraction often
requires significant manipulation and access through the ascending ramus
of the mandible.
Bone Removal:
A substantial amount of distal bone removal is necessary to access
the tooth adequately. This may involve the use of surgical instruments
to contour the bone and create sufficient space for extraction.
Crown Sectioning:
Once adequate bone removal has been achieved, the crown of the tooth
is typically sectioned from the roots just above the cervical line. This
step is crucial for improving visibility and access to the roots, which
can be difficult to see and manipulate in their impacted position.
Removal of the Crown:
The entire crown is removed to facilitate better access to the
roots. This step is essential for ensuring that the roots can be
addressed without obstruction from the crown.
Root Management:
Divergent Roots: If the roots of the tooth are
divergent (spreading apart), they may need to be further sectioned into
two pieces. This allows for easier removal of each root individually,
reducing the risk of fracture or complications during extraction.
Convergent Roots: If the roots are convergent
(closer together), a straight elevator can often be used to remove the
roots without the need for additional sectioning. The elevator is
inserted between the roots to gently lift and dislodge them from the
surrounding bone.
Surgical Technique Overview
Anesthesia: Local anesthesia is administered to ensure
patient comfort during the procedure.
Incision and Flap Reflection: An incision is made in the
mucosa, and a flap is reflected to expose the underlying bone and the
impacted tooth.
Bone Removal: Using a surgical bur or chisel, the distal
bone is carefully removed to create access to the tooth.
Crown Sectioning: The crown is sectioned from the roots
using a surgical handpiece or bur, allowing for improved visibility.
Root Extraction:
For divergent roots, each root is sectioned and removed
individually.
For convergent roots, a straight elevator is used to extract the
roots.
Closure: After the tooth is removed, the surgical site
is irrigated, and the flap is repositioned and sutured to promote healing.
Considerations and Complications
Complications: Distoangular impactions can lead to
complications such as nerve injury (especially to the inferior alveolar
nerve), infection, and prolonged recovery time.
Postoperative Care: Patients should be advised on
postoperative care, including pain management, oral hygiene, and signs of
complications such as swelling or infection.
Herpes zoster, or shingles
General Pathology
Herpes zoster, or shingles
- represents reactivation of a latent varicella-zoster infection.
- virus lies dormant in sensory dorsal root ganglia and when activated involves the distribution (dermatome) of the sensory nerve with a painful vesicular eruption.
- trigeminal verve distribution → Ramsay Hunt syndrome
- may indicate the presence of advanced neoplastic disease or be a complication of chemotherapy.
Acute viral hepatitis
General Pathology
Acute viral hepatitis
Clinical features. Acute viral hepatitis may be icteric or anicteric. Symptoms include malaise, anorexia, fever, nausea, upper abdominal pain, and hepatomegaly, followed by jaundice, putty-colored stools, and dark urine.
In HBV, patients may have urticaria, arthralgias, arthritis, vasculitis, and glomerulonephritis (because of circulating immune complexes). Blood tests show elevated serum bilirubin (if icteric), elevated transaminases, and alkaline phosphatase.
The acute illness usually lasts 4-6 weeks.
Pathology
(1) Grossly, there is an enlarged liver with a tense capsule.
(2) Microscopically, there is ballooning degeneration of hepatocytes and liver cell necrosis.