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Showing posts from April, 2011

Knee reflex / Knee jerk

Tapping the patellar tendon elicits the knee jerk (L 2,3, 4), a stretch reflex of the quadriceps femoris muscle, because the tap on the tendon stretches the muscle. A similar contraction is observed if the quadriceps is stretched manually. When a skeletal muscle with an intact nerve supply is stretched suddenly, it contracts. This response is called the stretch reflex . It is a type of monosynaptic reflex. The knee jerk reflex is an example of a deep tendon reflex (DTR) in a neurological exam and is graded on the following scale: 0 (absent), 1+ (hypoactive), 2+ (brisk, normal), 3+ (hyperactive without clonus), 4+ (hyperactive with mild clonus), and 5+ (hyperactive with sustained clonus). Absence of the knee jerk can signify an abnormality anywhere within the reflex arc, including the muscle spindle, the Ia afferent nerve fibers, or the motor neurons to the quadriceps muscle. In general the afferent loop is much more critical for reflex function than the efferent l

Richter hernia

The Richter hernia occurs when only the antimesenteric border of the bowel herniates through the fascial defect. The Richter hernia involves only a portion of the circumference of the bowel. As such, the bowel may not be obstructed, even if the hernia is incarcerated or strangulated, and the patient may not present with vomiting. The Richter hernia can occur with any of the various abdominal hernias and is particularly dangerous, as a portion of strangulated bowel may be reduced unknowingly into the abdominal cavity, leading to perforation and peritonitis.

Left ventricular hypertrophy - ECG

The most characteristic finding is increased amplitude of the QRS complex. R waves in leads facing the left ventricle (i.e., leads I, aVL, V 5 , and V 6 ) are taller than normal, whereas S waves in leads overlying the right ventricle (i.e., V 1 and V 2 ) are deeper than normal. In many patients, the ST segment is depressed and followed by an inverted T wave. In most cases, the ST segment slopes downward from a depressed J point and the T wave is asymmetrically inverted (formerly called a “strain” pattern). A widening of the QRS complex may be there i.e. more than 110 ms and also the QRS complex may be notched. Common diagnostic criteria include: 1) Sokolow - Lyon index : SV 1 + (RV 5 or RV 6 ) > 3.5 mV                                        : RaVL > 1.1 mV 2) Cornell voltage criteria : SV 3 + SaVL ≥ 2.8 mV (for men)                                        : SV 3 + SaVL ≥ 2.0 mV (for women)

Hypertension - management in African Americans

1) Increase dietary potassium intake 2) Limit dietary sodium intake to < 2.4 gm/day 3) Increase physical activity 4) Weight loss 5) All antihypertensive medications and combinations are effective 6) Multiple drug combinations may be required to achieve control 7) Angiotensin-converting enzyme (ACE) inhibitors and beta blockers as monotherapy may be less effective but should be used when indicated (e.g., renal disease, heart failure, post–myocardial infarction) 8) Thiazide diuretics and calcium channel blockers may have greater blood pressure–lowering efficacy 9) A higher incidence of angioedema occurs when using ACE inhibitors

Carotid sinus syncope

In this condition there is exaggerated vagal discharge following carotid sinus stimulation when doing simple tasks like shaving or buttoning a tight shirt collar or even head rotation. There is reflex vasodilation and decrease in the pulse. These may combine to reduce blood pressure and cerebral perfusion in some elderly patients, causing loss of consciousness. Carotid sinus hypersensitivity is diagnosed by applying gentle pressure over the carotid pulsation just below the angle of the jaw, where the carotid bifurcation is located. Pressure should be applied for 5 to 10 seconds. It should be done in both supine and upright position. A normal response to carotid sinus massage is a transient decrease in the sinus rate, slowing of atrioventricular (AV) conduction, or both. Carotid sinus hypersensitivity is defined as a sinus pause longer than 3 seconds in duration and a fall in systolic blood pressure of 50 mmHg or more.

Vasovagal syncope

This is caused by autonomic overactivity, usually provoked by emotional or painful stimuli, less commonly by coughing or micturition. It is also called as neurocardiogenic syncope. The mechanism is that directly or indirectly, the nucleus tractus solitarius is activated by the triggering stimuli and this leads to increased parasympathetic tone and decreased sympathetic tone. The vagal parasympathetic tone leads to negative chronotropic and negative inotropic effects. This causes a slowing in the heart rate and decreased contractility that leads to a drop in the cardiac output. The decreased sympathetic tone on the other hand leads to vasodilation which leads to a decrease in the total peripheral resistance. Both cause a decrease of blood pressure significant enough to lead to loss of consciousness. 'Malignant' vasovagal syndrome is a rare condition where syncopal attacks so frequent that they are significantly disabling . Recovery is rapid if the patient lies down.


The word 'patient' is derived from the Latin patiens , meaning sufferance or forbearance. The overall purpose of medical practice is to relieve suffering. It is important to make a diagnosis, to know how to approach treatment, and to design an appropriate scheme of management for each patient. It is therefore essential to understand each person as fully as possible, whatever their social class or ethnic and cultural background.

Food poisoning - Bacterial incubation period

Incubation period a) 1-6 hours Staphylococcus aureus Bacillus cereus . . . mainly fried rice b) 8-16 hours Clostridium perfringens Bacillus cereus c) > 16 hours Vibrio cholerae Enterotoxigenic Escherichia coli Enterohemorrhagic Escherichia coli Salmonella spp. Shigella spp. Campylobacter jejuni Vibrio parahemolyticus

Food poisoning - Staphylococcus aureus

It is a common cause of food poisoning. Cause: It is due to the inoculation of toxin-producing S.aureus into food by colonized food handlers. The enterotoxin is heat stable unlike the bacteria which dies on warming/cooking. The toxin stimulates the vagus nerve and the vomiting center of the brain. It also appears to stimulate intestinal peristaltic activity. Onset: Rapid onset usually within 1-6 hr. Clinical features: Nausea and vomiting, although diarrhea, hypotension, and dehydration may also occur. The rapidity of onset, the absence of fever, and the epidemic nature of the presentation arouse suspicion of food poisoning. Symptoms generally resolve within 8–10 h. Treatment is entirely supportive.

Harrison's quote . . .

No greater opportunity, responsibility, or obligation can fall to the lot of a human being than to become a physician.  In the care of the suffering, the physician needs technical skill, scientific knowledge, and human understanding.  Tact, sympathy, and understanding are expected of the physician, for the patient is no mere collection of symptoms, signs, disordered functions, damaged organs, and disturbed emotions.  The patient is human, fearful, and hopeful, seeking relief, help, and reassurance.

ACE inhibitors - dry cough

ACE inhibitors e.g enalapril remain one of the drug of choice to initiate anti hypertensive therapy. It acts by inhibiting the angiotensin converting enzyme and thus prevent the conversion of angiotensin I to angiotensin II. The latter is a potent vasoconstrictor. Since it is not being produced there is a resulting vasodilation and thus a decrease in the blood pressure. At the same time ACE inhibitors prevent the breakdown of bradykinin and sunbstance P. These 2 agents are potent protussive mediators in the respiratory tract and thus will cause dry cough. This is an indication to shift to angiotensin receptor blocker e.g. losartan.


The peritoneum is a thin membrane that lines the walls of the abdominal cavity and covers much of the viscera. The parietal peritoneum lines the walls of the cavity and the visceral peritoneum covers the viscera. Between the parietal and visceral layers of peritoneum is a potential space called as the peritoneal cavity. Abdominal viscera are either suspended in the peritoneal cavity by folds of peritoneum called as mesenteries or are outside the peritoneal cavity. Organs suspended in the cavity are referred to as intraperitoneal and organs outside the peritoneal cavity, with only one surface or part of one surface covered by peritoneum, are retroperitoneal. The peritoneal cavity is subdivided further into the greater sac and the omental bursa: the greater sac accounts for most of the space in the peritoneal cavity, beginning superiorly at the diaphragm and continuing inferiorly into the pelvic cavity-it is entered once the parietal peritoneum has been penetrated; the

Changes in Normal Hemoglobin/Hematocrit Values with Age

   Age/Sex                                         Hemoglobin g/dL                     Hematocrit %    At birth                                                     17                                          52   Childhood                                                 12                                          36   Adolescence                                              13                                          40   Adult man                                                  16 (±2)                                  47 (±6)   Adult woman (menstruating)                       13 (±2)                                  40 (±6)   Adult woman (postmenopausal)                  14 (±2)                                  42 (±6)   During pregnancy                                       12 (±2)                                   37 (±6)

Dermatology - common terms

Macule: A flat, colored lesion, <2 cm in diameter, not raised above the surface of the surrounding skin. Patch: A large (>2 cm) flat lesion with a color different from the surrounding skin. This differs from a macule only in size. Papule:  A small, solid lesion, <0.5 cm in diameter, raised above the surface of the surrounding skin and hence palpable Nodule: A larger (0.5–5.0 cm), firm lesion raised above the surface of the surrounding skin. This differs from a papule only in size Tumor: A solid, raised growth >5 cm in diameter. Plaque: A large (>1 cm), flat-topped, raised lesion; edges may either be distinct (e.g., in psoriasis) or gradually blend with surrounding skin (e.g., in eczematous dermatitis). Vesicle:  A small, fluid-filled lesion, <0.5 cm in diameter, raised above the plane of surrounding skin. Fluid is often visible, and the lesions are translucent Pustule:  A vesicle filled with leukocytes. The presence of pustules does not necess

Infective endocarditis - cutaneous signs

The signs are caused by deposition of immune complex in the capillary circulation. These include: 1) Splinter hemorrhages : These are linear, subungual, dark red streaks especially in the fingers, less commonly in the toes. They are probably due to embolism to the linear capillaries in the nail bed. 2) Osler's nodes  : These are painful, tender, pea-sized erythematous nodules in the pulps of fingers. They tend to occur in crops and are indicator of either embolism to distal digital arteries or an immunological phenomenon. 3) Janeway lesions : These are painless erythematous lesions on the palms. They blanch on pressure.

hemoptysis - causes

Non-respiratory tract sources Nasopharyngeal source of bleeding - epistaxis Upper Gastrointestinal Bleeding - look out for melena Common Causes of respiratory tract bleeding Infection (60-70% of Hemoptysis) Acute Bronchitis (26% of Hemoptysis) - mucoid also Pneumonia (10% of Hemoptysis) Staphylococcus aureus Pseudomonas aeruginosa - foul smelling Tuberculosis (8% of Hemoptysis) Fungal organisms (e.g. Aspergillosis) - with a black component also Influenza Lung Cancer (23% of Hemoptysis) Hemoptysis is rarely due to metastases Less common causes of respiratory tract bleeding Cardiovascular causes Pulmonary venous Hypertension Congestive Heart Failure - frothy Severe Mitral Stenosis Pulmonary Embolism Arteriovenous malformation Pulmonary causes Bronchiectasis Airway trauma or foreign body (esp. children) Lung Abscess Goodpasture's Syndrome Wegener's Granulomatosis Lupus pneumonitis

Russell's sign - anorexia nervosa

Russell’s sign, i.e., the development of calluses over the dorsum of the dominant hand as a result of repeated friction against the front teeth during self-induced emesis, is the most pathognomonic skin sign in anorexia nervosa. Russell’s sign is seen in 67% of patients with the purging subtype of anorexia nervosa.