About Visual fields

 A patient presents with a bilateral homonymous quadranopsia involving the right upper visual field. Which of the following represents the MOST likely anatomic location of the abnormality?

• (A) Prechiasmal, right side
• (B) Optic chiasm
• (C) Postchiasmal, prethalamic, left side
• (D) Occipital lobe, right side
• (E) Occipital lobe, left side

The answer is E.

Homonymous visual field cuts imply a postchiasmal location of the abnormality because this is the first point where fibers from the same visual field of both eyes join. Fibers further divide between the thalamus and occipital lobe into upper and lower quadrant visual fields. The most common location for quadranopsia defects is the occiptal lobe. Stroke, tumor, and atypical migraine may present with quadranopsia.
Visual fields are named from the perspective of the patient, i.e., the right visual field corresponds to the left side of the retina. Therefore, a right-sided visual field cut involves the left-sided neurologic tracks.

Preoperative dose of antibiotic

When vancomycin is used as a preoperative prophylactic antibiotic, it should be administered within ______ minutes of the start of surgery.

A) 15
B) 30
C) 60
D) 120
E) At the time of incision

Answer and Discussion

The answer is D.
Ideally, a preoperative dose of antibiotic should provide a sufficient antibiotic serum level throughout the surgery to combat organisms most likely to cause a site infection. It is recommended that the first dose be timed to occur within 60 minutes before the surgical incision is made. If a fluoroquinolone or vancomycin is chosen for prophylaxis, the first dose should be administered within 120 minutes of the start of surgery. If the surgery involves the use of a tourniquet (e.g., hip or knee arthroplasty), the antibiotic infusion should be completed before inflation of the tourniquet. For most surgeries, it is recommended that use of prophylactic antibiotics end within 24 hours after surgery.

Mindmap for Appendicitis

Revise appendicitis faster with this mindmap!

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Acanthosis nigricans in diabetes mellitus

You note the shown skin disorder during a general medical evaluation. You explain to the patient they are at risk for the development of:

A) Alzheimer's disease

B) tuberculosis

C) diabetes mellitus

D) Grave's disease

E) melanoma



 The answer is C. (Diabetes mellitus) 
Although the majority of cases of acanthosis nigricans are benign and associated with obesity, the disease can represent the onset of malignancy as well as a variety of conditions related to insulin resistance.
Acanthosis nigricans has been reported in association with a number of malignancies, particular gastrointestinal cancers (e.g., gastric, hepatocellular) and lung cancer. The suspicion for malignancy increases in patients with extensive or rapidly progressive lesions, when there is mucous membrane involvement, or when there is prominent sole and palm disease.

The common finding in all non-malignancy associated cases of acanthosis nigricans is insulin resistance. This explains the relationship between this skin disorder and diseases such as diabetes mellitus, Cushing's syndrome, and hypothyroidism (most likely due to weight gain and subsequent insulin resistance), and with obesity.

Photos of Melanosis coli "Pseudomelanosis coli"

Melanosis coli, also pseudomelanosis coli, is a disorder of pigmentation of the wall of the colon, often identified at the time of colonoscopy.
The most common cause of melanosis coli is the extended use of laxatives, this darkening of the colonic mucosa caused by the accumulation of lipofuscin particles within the macrophages of the lamina propria of the colonic mucosa as a result of long term exposure to anthraquinone-containing laxatives as Senna and other plant glycosides. However, other causes are identified, including an increase in colonic epithelial apoptosis.

This is the photograph of the colon, and there is an extremely dark appearance to the wall of the colon. This is seen in patients who have taken laxatives over many years and the pigment from the laxative gets deposited in the wall of the bowel giving an extremely dark appearance to it. This is a benign condition, not cancerous, and does not become cancerous, but often it is quite obvious.

- Melanosis coli is a misnomer, as the pigmentation is due to lipofuscin-laden macrophages - not melanin pigment. Pseudomelanosis coli is a more appropriate descriptor, but not in common usage.

The differential diagnosis of brown pigmentation of the colon is:

* Pseudomelanosis coli.
* Hemosiderin-laden macrophages (old haemorrhage).
* Melanin (rare).

Vacuum Assisted Delivery: A Brief Summary of Key Principles

Decompression sickness "divers' disease"

A 55-year-old male diver begins complaining of back pain and urinary retention 1 h after a dive. What is the MOST likely diagnosis?

• (A)Barotrauma to the bladder


• (B)Lumbar strain


• (C)Neurotoxin from a marine envenomation


• (D)Nitrogen narcosis


• (E)Decompression sickness

The answer is E.

Barotrauma is the most common affliction of divers and usually affects the ears, sinuses, lungs, and, rarely, the gastrointestinal tract. The bladder is not involved.

Decompression sickness (DCS),also known as divers' disease, the bends or caisson disease, is caused by formation of gas bubbles in tissues after ascent from a dive and results in vascular occlusion, usually in the venous circulation. DCS may have cutaneous manifestations including rash and pruritus. It classically causes joint and back pain and may be associated with neurologic symptoms secondary to spinal cord involvement.

Patients with neurologic or other severe forms of DCS should be referred for hyperbaric oxygen therapy. Nitrogen narcosis is due to the anesthetic effects of breathing nitrogen at high partial pressures and causes divers to become altered on deep dives.