First Aid for the USMLE Step 2 CS

Section 3. Minicases

Loss Of Consciousness

Key History

Presence or absence of preceding symptoms (nausea, diaphoresis, palpitations, pallor, lightheadedness), context (exertional, postural, traumatic; stressful, painful, or claustrophobic experience; dehydration); associated tongue biting or incontinence, tonic-clonic movements, prolonged confusion; dyspnea or pulmonary embolism risk factors; history of heart disease, arrhythmia, hypertension, or diabetes; alcohol and drug use.

Key Physical Exam

Vital signs, including orthostatics; complete neurologic exam; carotid and cardiac exam; lung exam; exam of the lower extremities.

Presentation

Differential

Workup

■ 26 yo M presents after falling and losing consciousness at work. He had rhythmic movements of the limbs, bit his tongue, and lost control of his bladder. He was subsequently confused after regaining consciousness (as witnessed by his colleagues).

Generalized tonic-clonic seizure

Convulsive syncope

Substance abuse/overdose

Malingering

Hypoglycemia

CBC

Electrolytes, glucose

Urine toxicology

EEG

MRI—brain

CT—head

LP—CSF analysis

ECG

LOSS OF CONSCIOUSNESS (cant'd)

Presentation

Differential

Workup

■ 55 yo M c/o falling after feeling dizzy and unsteady. He experienced transient loss of consciousness. His past medical history is significant for hypertension and diabetes mellitus.

Drug-induced orthostatic hypotension (causing syncope)

Hypoglycemia

Cardiac arrhythmia

Syncope (vasovagal, other causes)

Stroke

MI

Pulmonary embolism

Orthostatic vital signs CBC

Electrolytes, glucose

Echocardiography

CT—head

ECG

V/Q scan

CTA—chest with IV

contrast

D-dimer

■ 65 yo M presents after falling and losing consciousness for a few seconds. He had no warning before passing out but recently had palpitations. His history includes a coronary artery bypass graft.

Cardiac arrhythmia

(causing syncope)

Severe aortic stenosis

Syncope (other causes)

Seizure

Pulmonary embolism

ECG

Holter monitoring

CBC

Electrolytes, glucose

Echocardiography

CT—head

 

Numbness/Weakness

Key History

Distribution (unilateral, bilateral, proximal, distal), duration, ± progression, pain (especially headache, neck or back pain); constitutional symptoms, other neurologic symptoms; history of diabetes, alcoholism, atherosclerotic vascular disease.

Key Physical Exam

Vital signs; neurologic and musculoskeletal exams; relevant vascular exam.

Presentation

Differential

Workup

■ 68 yo M presents following a 20-minute episode of slurred speech, right facial drooping and numbness, and right hand weakness. His symptoms had totally resolved by the time he got to the emergency department. He has a history of hypertension, diabetes mellitus, and heavy smoking.

Transient ischemic attack

(TIA)

Hypoglycemia

Seizure

Stroke

Facial nerve palsy

CT—head

CBC

Electrolytes, glucose

Fasting lipid panel

ECG

MRI—brain

Doppler U/S—carotid

Echocardiography

EEG

NUMBNESS/WEAKNESS (cont'd)

Presentation

Differential

Workup

 68 yo M presents with slurred speech, right facial drooping and numbness, and right hand weakness. Babinski’s sign is present on the right. He has a history of hypertension, diabetes mellitus, and heavy smoking.

Stroke

TIA

Seizure

Intracranial neoplasm Subdural or epidural hematoma

CT—head

CBC

Electrolytes

PT/PTT/INR

Fasting lipid panel

MRI—brain

Doppler U/S—carotid

Echocardiography

ECG

■ 33 yo F presents with ascending loss of strength in her lower legs over the past 2 weeks. She had a recent URI.

Guillain-Barré syndrome

Multiple sclerosis Polymyositis Myasthenia gravis Peripheral neuropathy Tumor in the vertebral canal

CBC

Electrolytes

CPK

LP—CSF analysis

MRI—spine

EMG

Nerve conduction studies Tensilon (edrophonium) test

Serum B12

■ 30 yo F presents with weakness, loss of sensation, and tingling in her left leg that started this morning. She is also experiencing right eye pain, decreased vision, and double vision. She reports feeling “electric shocks” down her spine upon flexing her head.

Multiple sclerosis

Stroke

Conversion disorder Malingering CNS tumor Neurosyphilis Syringomyelia CNS vasculitis

CBC

ESR

VDRL/RPR MRI—brain, spine LP—CSF analysis Retinal evoked potentials

■ 55 yo M presents with tingling and numbness in his hands and feet (glove-and-stocking distribution) for the past 2 months. He has a history of diabetes mellitus, hypertension, and alcoholism. There is decreased soft touch, vibratory, and position sense in the feet.

Diabetic peripheral neuropathy

Alcoholic peripheral neuropathy B12 deficiency Hypocalcemia Hyperventilation Paraproteinemia/myeloma

HbA,

1c

ESR Calcium Serum B12 UA

Serum and urine protein electrophoresis

NUMBNESS/WEAKNESS (cant'd)

Presentation

Differential

Workup

■ 40 yo F presents with occasional double vision and droopy eyelids at night with normalization by morning.

Myasthenia gravis

Horner’s syndrome

Multiple sclerosis

Intracranial neoplasm compressing CN III, IV, or VI

Amyotrophic lateral sclerosis

Tensilon (edrophonium) test

Serum ACh receptor

antibodies

CXR

CT—chest

MRI—brain

EMG

■ 25 yo M presents with hemiparesis after a tonic- clonic seizure that resolved within a few hours.

Todd’s paralysis

TIA

Stroke

Complicated migraine

Malingering

CBC

Electrolytes

EEG

MRI—brain

Doppler U/S—carotid

■ 56 yo obese F c/o tingling and numbness of her thumb, index finger, and middle finger for the past 5 months. Her symptoms are constant, have progressively worsened, and are relieved with rest. She works as a secretary. She has a history of fatigue and a 20-lb (9-kg) weight gain over the same period.

Carpal tunnel syndrome secondary to hypothyroidism

Overuse injury of median nerve

Medial epicondylitis

Phalen’s maneuver and

Tinel’s sign

Nerve conduction studies

TSH

CBC





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