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Showing posts from January, 2012

Romberg's test - how to do and interpretation

 INTRODUCTION  Romberg's test is done to assess the integrity of the dorsal columns of the spinal cord. It is not a test to assess the cerebellar function. The test was first described by Moritz Heinrich von Romberg who found that patients with tabes dorsalis (neurosyphilis) often complained of increased unsteadiness in the dark. The test should be performed in all patients who complain of dizziness, imbalance or falls to rule out sensory ataxia.  HOW TO DO THE TEST?  The test is done by requesting the patient to keep his feet firmly together, arms by the side and the eyes open at first. The balance of the patient is noted. Now the patient is asked to close both eyes and the balance is now noted for around 1 minute. The physician should stand in front of the patient with his arms extended on either side of the patient but not touching him. This is done as the latter may fall.  INTERPRETATION  1) If with the eyes open, the balance is not good then there may be a probl

Retropharyngeal abscess - X-ray

Retropharyngeal abscess is a rare condition presenting in infants (<1 year of age). Clinical symptoms include fever and drooling.  As a result of the swelling within the posterior pharyngeal wall causing upper airway obstruction, the child will typically hold their neck in extension to assist breathing.  A lateral soft tissue neck radiograph taken with the neck held in extension is indicated if a retropharyngeal abscess is suspected. If it is positive, it will demonstrate air within the swollen retropharyngeal tissues, as shown by the x-ray above. A contrast enhanced computerized  tomography (CT) examination will confirm the diagnosis.

Difference between factitious disorder and malingering

Persons with factitious disorder fake illness. They simulate, induce, or aggravate illness. They also often inflict painful and even life-threatening injury on themselves or those under their care. Unlike malingerers who have material goals, such as monetary gain or avoidance of duties, patients with factitious disorder bear the sufferings primarily to gain the emotional care and attention that comes with playing the role of the patient. The disorders have a compulsive quality, but the behaviors are considered voluntary in that they are deliberate and purposeful, even if they cannot be controlled.

Percutaneous coronary intervention

PCI consists of balloon angioplasty followed by stenting. Balloon angioplasty expands the coronary lumen by stretching and tearing the atherosclerotic plaque and vessel wall. The atherosclerotic plaque is also redistributed a little along its longitudinal axis. Elastic recoil of the stretched vessel wall generally leaves a 30 to 35 percent residual diameter stenosis. Although stand-alone balloon angioplasty is rarely used other than for very small (<2.25 mm) vessels, balloon angioplasty remains integral to PCI for predilating lesions before stent placement, deploying coronary stents, and further expanding stents after deployment. Coronary stents are currently used in more than 90 percent of PCI procedures worldwide. Coronary stents lowers the incidence of vessel closure. Restenosis after coronary stent placement occurs in some patients due to excessive intimal hyperplasia within the stent. While bare metal coronary stents reduce the incidence of angiographic and clinica

Sickle cell disease - Electrophoresis

Above is an electrophoresis of a patient suspected to have sickle cell disease. A blood sample was taken from him and the erythrocytes were separated. After lysis of the RBCs, hemoglobin was released and it was run on a polyacryamide gel. Electrophoresis was carried out and Western blot was performed to located the hemoglobin. The principle of electrophoresis is that the the more negatively charged particles move towards the positive pole and vice versa. In the case of sickle cell disease, glutamate is substituted by valine at the 6th position of the beta chain. This removes a negative charge from the chain and thus in the electric field the mutated chain will not move as far towards the positive pole as does the non-mutated chain. The interpretation is as follows: 1) X is a band that represents the mutated HbS. 2) Y is the normal Hb. 3) 1 is a carrier of HbS i.e. having one normal and one mutated chain. 4) 2 is a person who does not carry any mutant alleles. 5) 3 is a per

Shoulder joint / Glenohumeral joints

The shoulder joint is a synovial multi-axial spheroidal joint. It occurs between the roughly hemispherical head of the humerus and the shallow glenoid fossa of the scapula. Since there is no major bony constraint, the joint has 3 degrees of freedom. It is the most mobile joint of the body and allows all the movements shown above. The stability of the joint depends on the surrounding muscular and soft tissue envelope. It is one of the most frequently dislocated joints in the body.

Neck compartments

The neck has 4 major compartments. 1) Vertebral compartment which is contains the cervical vertebrae and associated muscles of posture, 2) Visceral compartment which contains the thyroid, thymus and parathyroid as well as the esophagus and larynx, 3) 2 vascular compartments on both sides and these contain the major blood vessels and vagus nerve.

Major tachycardias

Narrow QRS complex     A.     Sinus tachycardia              B.     Paroxysmal supraventricular tachycardias (PSVTs)                      1.      Atrial tachycardias, including single-focus or multifocal (MAT) variants                        2.     AV nodal reentrant tachycardia (AVNRT)                       3.     AV reentrant tachycardia (AVRT) involving a bypass tract              C.     Atrial flutter              D.     Atrial fibrillation  Wide QRS complex     A.     Ventricular tachycardia                B.     SVT/AF or flutter, with aberrant ventricular conduction usually caused by either of the following:   1.     Bundle branch block patterns                          2.     Atrioventricular bypass tract (Wolff-Parkinson-White preexcitation patterns)  

Hemodialysis - when to start? / Calculation of normalized eGFR

Hemodialysis should be started when: 1) eGFR is < 6  mL/min/1.73  m 2 2) eGFR is < 15  mL/min/1.73  m 2   and patient is showing signs and symptoms of uremia, unable to control his hydration and blood pressure.  Cockcroft-Gault formula  is a very commonly used formula to get an estimate of the GFR. The unit for eGFR is  mL/min. The classification for stages of chronic kidney diseases  on the other hand is based on normalized eGFR i.e. the eGFR per 1.73  m 2  and the unit being mL/min/1.73   m 2 . Thus we also need to calculate the surface area of the patient's body. It is given by the formula as follows :  Body Surface Area ( m 2 ) = ( [Height(cm) x Weight(kg) ]/ 3600 )½ And the normalized eGFR ( mL/min/1.73   m 2 ) = (eGFR/BSA) x 1.73 A clinical example is given below.   A 45 year old man weighing 70 kg and 180 cm tall has been admitted to the hospital because of fluid overload. He has been treated for the past hours with diuretics but has not been im

Homeostasis - negative feedback loop

A rise of some factor e.g. X of the internal environment is detected by the sensor. This information is relayed to the integrating center that causes the effector to produce a change in the opposite direction. The initial deviation is thus reversed, thus completing the negative feedback loop. The same holds true if the factor X is decreased. The integrating center detects a change from the set point and causes necessary effects to bring it back to normal. Below is a diagram that shows negative feedback loops maintain a state of dynamic consistency within the internal environment.  One such example is regulation of body temperature as explained in the link that follows.  Regulation of body temperature

Penicillin - a fortunate accident

It all started when Alexander Fleming discarded some of his culture plates that had been contaminated with mold. But fortunately, he had a second look to those cultures afterwards. He was amazed to see that in the area around the mold, the growth of bacteria was inhibited. The mold was identified as Penicillium notatum, the active inhibitor named penicillin. Above is a photo taken by Alexander Fleming in 1928.

Antonie van Leeuwenhoek

He was a Dutch merchant and amateur scientist. He was probably the first person to observe live micro-organisms under magnifying lenses. He made a series of drawings of what he called as 'animalcules' i.e. small animals. He observed these by looking through his single-lens microscope at rainwater, his own feces and scrapings from his teeth. He made the drawings shown below.

Cullen's sign

It refers to the superficial peri-umbilical bruising of the subcutaneous fat. It can be seen in the following cases: 1) acute pancreatitis (classically), 2) bleeding from blunt abdominal trauma, rupture of abdominal aorta and ruptured ectopic pregnancy. The sign was actually first described by Thomas Cullen in 1916 in a case of ruptured ectopic pregnancy.

Abciximab - mechanism of action/ indication/ contraindication/ dose

It is a Fab fragment of a humanized monoclonal antibody directed against the glycoprotein IIb/IIIa. The latter is a platelet surface integrin. It is a receptor for fibrinogen which binds platelets to each other causing aggregation. By inhibiting the receptor, abciximab acts as a potent antiplatelet agent.  Indications: 1) myocardial ischemia, 2) percutaneous coronary intervention. Dose: 1) For M.I - initially an I.V bolus of 0.25 mg/kg over 5 min followed by 0.125 µg/kg/min (to a maximum of 10 µg/min) for 12 hours. 2) For P.C.I - initially, 0.25 mg/kg I.V bolus over 5 min 20-60 min prior to angioplasty followed by 0.125 µg/kg/min (to a maximum of 10 µg/min) for next 12 hours. Contraindications: 1) bleeding disorder or use of anticoagulant within 7 days, 2) CVA within 2 years, 3) known allergy to this product, 4) major trauma or surgery within 6 weeks, 5) severe uncontrolled hypertension, 6) active internal bleeding, 7) thrombocytopenia i.e pla

Chickenpox - dew on rose petal appearance

Definition: Chickenpox is a benign viral disease of childhood, characterized by an exanthematous vesicular rash. It is an extremely common and contagious condition. It is caused by the varicella-zoster virus which is a herpes virus and contains a double stranded DNA in its center. Epidemiology: Age group affected- 5 to 9 years. The infection can be there at other ages too but it is less frequent. It is highly contagious and it affects all races and both sexes equally. The attack rate is around 90% among seronegative persons. Pathogenesis: Incubation period- 10 to 21 days but is usually 14 to 17 days. Patients are infectious around 48 hours from onset of vesicular rash, during the period of vesicular formation (around 4-5 days) and until all vesicles are crusted. Transmission occurs by respiratory route. The virus is believed to be localized in the nasopharynx, in the reticulo-endothelial system. It then enters the blood. This stage of viremia is characterized by diffused ski