RAYNAUD'S PRESENTATION

Q. A 45-year-old woman has pain in her fingers on exposure to cold, arthralgias, and difficulty swallowing solid food. What is the best diagnostic test?

a. Rheumatoid factor

b. Antinucleolar antibody

c. ECG

d. BUN and creatinine

e. Reproduction of symptoms and findings by immersion of hands in cold water

Ans:  b.

The symptoms of Raynaud phenomenon, arthralgia, and dysphagia point toward the diagnosis of scleroderma. Scleroderma, or systemic sclerosis, is characterized by a systemic vasculopathy of small and medium-sized vessels, excessive collagen deposition in tissues, and an abnormal immune system. It is an uncommon multisystem disease affecting women more often than men. There are two variants of scleroderma—a relatively benign type called the CREST syndrome and a more severe, diffuse disease. Antinucleolar antibody occurs in only 20 to 30% of patients with the disease, but a positive test is highly specific. Cardiac involvement may occur, and an ECG could show heart block but is not at all specific. Renal failure can develop insidiously, but BUN and creatinine levels would not be diagnostically specific. Rheumatoid factor is nonspecific

and present in 20% of patients with scleroderma. Reproduction of Raynaud phenomena is nonspecific and is not recommended as an office test.

GOUTY ARTHRITIS

Q. A 40-year-old man complains of exquisite pain and tenderness in the left ankle. There is no history of trauma. The patient is taking hydrochlorothiazide for hypertension. On examination, the ankle is very swollen and tender. There are no other physical examination abnormalities. Which of the following is the best next step in management?

a. Begin colchicine and broad-spectrum antibiotics.

b. Perform arthrocentesis.

c. Begin allopurinol if uric acid level is elevated.

d. Obtain ankle x-ray to rule out fracture.

e. Apply a splint or removable cast.

Ans:  b.

The sudden onset and severity of this monoarticular arthritis suggests acute gouty arthritis, especially in a patient on diuretic therapy. However, an arthrocentesis is indicated in the first episode to document gout by demonstrating needle-shaped, negatively birefringent crystals and to rule out other diagnoses such as infection. The level of serum uric acid during an episode of acute gouty arthritis may actually fall. Therefore, a normal serum uric acid does not exclude a diagnosis of gout. For most patients with acute gout, NSAIDs are the treatment of choice.

Colchicine is also effective but causes nausea and diarrhea. Antibiotics should not be started for suspected septic arthritis before an arthrocentesis is performed. Treatment for hyperuricemia should not be initiated in the setting of an acute attack of gouty arthritis. Long-term goals of management are to control hyperuricemia, prevent further attacks, and prevent joint damage.

Long-term prophylaxis with allopurinol is considered for repeated attacks of acute arthritis, urolithiasis, or formation of tophaceous deposits. X-ray of the ankle would likely be inconclusive in this patient with no trauma history. In the absence of trauma, there is no indication for immobilization

SEPTIC ARTHRITIS

Q. A 70-year-old man complains of fever and pain in his left knee. Several days previously, he suffered an abrasion of his knee while working in his garage. The knee is red, warm, and swollen. An arthocentesis is performed, which shows 200,000 leukocytes/μL and a glucose of 20 mg/dL. No crystals are noted. Which of the following is the most important next step?

a. Gram stain and culture of joint fluid

b. Urethral culture

c. Uric acid level

d. Antinuclear antibody

e. Antineutrophil cytoplasmic antibody

Ans:  a.

 The clinical and laboratory picture suggests an acute septic arthritis. The most importantfirst step is to determine the etiologic agent of the infection. Synovial leukocyte counts in gout typically range between 2000/μL and 50,000/μL; in addition, serum uric acid levels are often normal in acute gout. In the absence of negatively birefringent crystals in the synovial fluid, a uric acid level will not be helpful. There are no symptoms suggesting connective tissue disease. Gonococci can cause a septic arthritis, but a urethral culture in the absence of urethral discharge would not be helpful. Antineutrophil cytoplasmic antibodies are present in certain vasculitides. There is no indication of systemic vasculitis in this patient.

NEUROANATOMY

NEURO ANATOMY

Q. Which motor neurons activate both intrafusal and extrafusal muscle fibers?

A) α-motor neurons

B) β-motor neurons

C) Renshaw cells

D) Golgi tendon organs

E) γ-motor neurons

Ans:  B)

 α-Motor neurons are located in the anterior horn of the spinal cord and activate extrafusal muscle fibers responsible for muscle contraction. γ-Motor neurons innervate intrafusal fibers, which have small axons and control the level of tension on the muscle spindle to control overall muscle length and tone. β-Motor neurons innervate both intrafusal and extrafusal muscle fibers. Renshaw cells are found in the ventral horn and send inhibitory signals to the α-motor neurons. Golgi tendon organs are located in muscle tendons and send inhibitory signals to α-motor neurons that have input to extrafusal muscle fibers, which mediate the inverse stretch reflex.

Q. An injury to the peroneal nerve affects which muscle?

A) Semimembranosus

B) Semiteninosus

C) Adductor magnus

D) Short head of the biceps femoris

E) Long head of the biceps femoris

Ans: D)

The short head of the biceps femoris is the only muscle above the knee that is innervated by the peroneal nerve. The semimembranosus, semitendinosus, and long head of the biceps femoris muscles are innervated by the tibial nerve. The adductor magnus muscle is innervated by the obturator nerve.

Q. Which key neurotransmitter is responsible for innervation of sweat glands?

A) Norepinephrine

B) Dopamine

C) Acetylcholine

D) Serotonin

E) Glutamate

Ans C)

Acetylcholine is the neurotransmitter found in sweat glands. Serotonin, glutamate, and dopamine are central nervous system neurotransmitters not involved in direct innervation of sweat glands.

Q. Which nerve bundle is involved in postganglionic supply to the parotid gland?

A) Submandibular ganglion

B) Superior salivatory nucleus

C) Pterygopalatine ganglion

D) Otic ganglion

E) Inferior salivatory nucleus

Ans: D) The inferior salivatory nucleus projects preganglionic fibers along the glossopharyngeal nerve to the otic ganglion, which in turn projects postganglionic fibers to the parotid gland to stimulate saliva production. The superior salivatory nucleus projects fibers along the facial nerve to the preganglionic fibers to the pterygopalatine ganglion and submandibular ganglion. The pterygopalatine ganglion projects postganglionic fibers to the lacrimal gland and to the mucosa of the nose and palate.

The submandibular ganglion projects postganglionic fibers to the submandibular and sublingual glands.

Q.  You are seeing a patient for visual difficulties. On examination, you find that he has a right lower homonymous quadrantanopsia. Where do you localize the lesion?

A) Pituitary tumor

B) Optic radiation in the left temporal lobe

C) Optic radiation in the left occipital lobe

D) Optic radiation in the left parietal lobe

E) Left frontal lobe

Ans: D) A lesion affecting the optic radiation in the left parietal lobe may result in a right lower homonymous quandrantanopia. A pituitary tumor will usually result in a bitemporal hemianopsia. A lesion of the optic radiation in the left temporal lobe may result in a right upper homonymous quadrantanopia. A lesion of the optic radiation of the left occipital lobe results in a right homonymous hemianopsia. The optic radiation does not run through the frontal lobe. However, the frontal eye field lies in the frontal lobe, and a lesion may cause a gaze palsy in the direction of the side of the lesion.

Q. Which first-order receptor cell in the retina is responsible for day vision, color vision, and high visual acuity?

A) Rods

B) Bipolar neurons

C) Ganglion cells

D) Amacrine cells

E) Cones

Ans: E)

Cones operate at high illumination levels and are responsible for day vision, color vision, and high visual acuity. Rods are sensitive to low-intensity light and are responsible for night vision. Bipolar neurons and amacrine cells transmit stimulation from rods and cones to ganglion cells, which transmit the signals to the hypothalamus, superior colliculus, pretectal nucleus, and lateral geniculate body.

Q. Which structure is involved in the accommodation pathway but not in the pupillary

reflex?

A) Corticotectal tract

B) Posterior commissure

C) Edinger-Westphal nucleus

D) Brachium of superior colliculus

E) Short ciliary nerve

Ans: A)

The corticotectal tract is involved in relaying signal from the occipital lobe through the brachium of the superior colliculus to the accommodation center, which sends a signal to the Edinger-Westphal nucleus or the oculomotor nucleus to initiate accommodation. All other structures are involved in both the papillary reflex pathway and accommodation.

Q. A lesion of which hypothalamic nucleus will most likely result in disruption of the

circadian rhythm?

A) Supraoptic

B) Suprachiasmatic

C) Lateral hypothalamic nucleus

D) Anterior nucleus

E) Paraventricular nucleus

Ans: B)

 The suprachiasmatic nucleus receives direct input from the retina and plays a role in the circadian rhythm. The supraoptic nucleus synthesizes antidiuretic hormone and oxytocin. The lateral hypothalamic region, when stimulated, increases appetite, and destruction results in anorexia and starvation. The anterior nucleus takes part in regulating temperature, and destruction results in hyperthermia. The paraventricular nucleus regulates antidiuretic hormone, and destruction of this nucleus results in diabetes insipidus.

Q. Which is the only excitatory neuron in the cerebellar cortex?

A) Purkinje neuron

B) Basket neurons

C) Stellate cell

D) Granule cell

E) Golgi neuron

Ans: D)

The granule cell is the only excitatory neuron in the cerebellar cortex that is excitatory and stimulates the purkinje, baset, stellate, and golgi cells. Stellate and basket neurons inhibit Purkinje neurons. Golgi neurons inhibit granule cells. Purkinje neurons inhibit neurons in the cerebellar nuclei

Q. Which artery supplies the head of the caudate nucleus?

A) Middle cerebral artery

B) Paracentral artery

C) Pericallosal artery

D) Callosomarginal artery

E) Recurrent artery of Heubner

Ans: E)

Recurrent artery of Heubner. The recurrent artery of Heubner is a branch of the anterior cerebral artery that supplies the anteromedial head of the caudate nucleus.

The pericallosal artery and callosomarginal artery are also branches of the anterior cerebral artery that supply the corpus callosum. The paracentral artery is a branch off the callosomarginal artery that supplies the paracentral lobule (medial part of superior frontal gyrus)

Q. Which of these structures is involved in the auditory system?

A) Superior salivatory nucleus

B) Inferior salivatory nucleus

C) Inferior olivary nucleus

D) Lateral lemniscus

E) Superior colliculus

Ans: D)

The lateral lemniscus carries fibers from the superior olivary nucleus to the inferior colliculus as part of the auditory system. The superior salivatory nucleus projects preganglionic parasympathetic fibers to the pterygopalatine (to the lacrimal gland) and submandibular ganglia (to the submandibular gland). The inferior salivatory nucleus projects preganglionic parasympathetic fibers to the otic ganglion (which then supplies the parotid gland). The superior colliculus is part of the visual system. The inferior olivary nucleus is involved in Mollaret’s triangle, and lesions can contribute to the development of palatal tremor (formerly known as palatal myoclonus).