WBR0574

Author	[[PageAuthor::Rim Halaby, M.D. [1]]]
Exam Type	ExamType::USMLE Step 1
Main Category	MainCategory::Pathology, MainCategory::Pathophysiology
Sub Category	SubCategory::Neurology
Prompt	[[Prompt::A 66 year old woman with recent hip fracture after a fall presents to the neurology clinic with complaints of hand tremor. She noticed the tremor a few months ago, and although it has not increased significantly since then, she explains that it is very bothersome and interferes with her daily activities. The patient notices the tremor only when conducting activities that require the use of her arms. On exam, you notice no baseline tremor, but when the patient is asked to reach for a pen she exhibits a slow, coarse, zigzag motion of her hand as she extends for it. The tremor increases in intensity as the patient’s hand gets closer to the object. You also notice that the patient requires a few attempts before grabbing the pen often overshooting the actual location. What is the most likely cause of her tremor?]]
Answer A	AnswerA::Genetic predisposition
Answer A Explanation	[[AnswerAExp::Essential or postural tremor is usually due to genetic predisposition. It is typically a tremor associated with maintenance of a certain posture (ex. outstretched arms, pouring water, drinking from a cup). The tremor can involve the hands, the head, and even the voice. Many risk factors have been linked to essential tremor including age, Caucasian race, and family history. The tremor is usually exacerbated by stress, fever, caffeine, and β-adrenergic agonists among others. Patients classically self-medicate with alcohol that decreases the intensity of the tremor. Treatment is usually with β-blockers.]]
Answer B	AnswerB::Excessive caffeine consumption
Answer B Explanation	[[AnswerBExp::Stress, fever, caffeine, and β-adrenergic agonists usually exacerbate a pre-existing tremor in patients with essential (postural) tremor or Parkinson's disease. Excessive caffeine consumption can lead to a low amplitude tremor in a small minority of patients with no underlying disease.]]
Answer C	AnswerC::Cerebellar lesion
Answer C Explanation	[[AnswerCExp::Intention tremor secondary to a cerebellar lesion is characterized by a slow, coarse, and zigzag motion that is observed when the patient is reaching for a target ex. finger-to-nose testing. It becomes more prominent as the patient approaches the desired object, often missing the actual location. It can be either bilateral or unilateral depending of the location of the cerebellar lesion]]
Answer D	AnswerD::Dopamine depletion in the substantia nigra
Answer D Explanation	[[AnswerDExp::Parkinson’s disease involves dopamine depletion from the substantia nigra leading to resting tremor, bradykinesia and cogwheel rigidity. Resting tremor is the presenting complaint of 70% of patients with Parkinson’s disease. In most cases the tremor is present at rest and abates if the patient is asked hold his hands outstretched for a period of time.]]
Answer E	AnswerE::Caudate atrophy
Answer E Explanation	[[AnswerEExp::Caudate atrophy is seen in Huntington’s disease and usually does not cause tremor. Huntington’s disease typically causes chorea and athetosis. Chorea refers to sudden, jerky involuntary movements while athetosis describes slow, convoluted, writhing movements classically seen in the fingers]]
Right Answer	RightAnswer::C
Explanation	[[Explanation::Kinetic tremor (intention tremor) is a tremor that occurs during voluntary movement. The above presentation closely represents the classical findings of intention tremor associated with cerebellar dysfunction. The tremor is characterized by a low frequency, coarse motion that is accentuated as the patient gets closer to a desired target. Dysmetria is also often associated referring to a lack of coordination leading to an overshoot or undershoot phenomenon that causes the patient to miss the intended target. Typically, finger-to-nose testing will reveal the tremor. Intention tremors can be isolated or associated with ataxia or other cerebellar symptoms. This patient has a history of fall and hip fracture which may be related. Other causes of intention tremor include multiple sclerosis and Wilson’s disease. Educational Objective: Intention tremor or kinetic tremor is a slow, low-amplitude motion seen when a ptient is reaching for a target. It is associated with cerebellar lesions or atrophy. References: Elble RJ. Tremor: clinical features, pathophysiology, and treatment. Neurol Clin. 2009;27(3):679-95, v-vi. Louis ED. Essential tremor. Lancet Neurol. 2005;4(2):100-10. Educational Objective: References: ]]
Approved	Approved::No
Keyword	WBRKeyword::Tremor, WBRKeyword::Cerebellum, WBRKeyword::Intentional tremor, WBRKeyword::Essential tremor
Linked Question	Linked::
Order in Linked Questions	LinkedOrder::