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I-69. The answer is C. (Chap. 16) Hyperthermia occurs when exogenous heat exposure or an endogenous heat-producing process, such as neuroleptic malignant syndrome or malignant hyperthermia, leads to high internal temperatures despite a normal hypothalamic temperature set point.

Fever occurs when a pyrogen such as a microbial toxin, microbe particle, or cytokine resets the hypothalamus to a higher temperature. A particular temperature cutoff point does not define hyperthermia. Rigidity and autonomic dysregulation are characteristic of malignant hyperthermia, a subset of hyperthermia. Fever, not hyperthermia, responds to antipyretics.

I-70. The answer is E. (Chap. 17) Elderly adults and young children are at highest risk of nonexertional heat stroke. Environmental stress (heat wave) is the most common precipitating factor, particularly in bedridden individuals and individuals living in poorly ventilated or non–air-conditioned conditions. Medications such as antiparkinson treatment, diuretics, and anticholinergics increase the risk of heat stroke.

I-71. The answer is A. (Chap. 17) Based on the characteristic rash and Koplik’s spots, this patient has measles. A rare but feared complication of measles is subacute sclerosing panencephalitis. His examination does not support epiglottitis because he has no drooling or dysphagia. His rash is not characteristic of acute HIV infection, and he lacks the pharyngitis and arthralgias commonly seen with this diagnosis. The rash is not consistent with herpes zoster, and he is quite young to have this condition. Splenic rupture occasionally occurs with infectious mononucleosis, but this patient has no pharyngitis, lymphadenopathy, or splenomegaly to suggest this diagnosis. Because of mandatory vaccination, measles is very uncommon in the United States (as well as central and south America); almost all cases are imported. However, countries with lower rates of vaccination still have endemic measles.

I-72. The answer is C. (Chap. 17) This case is likely toxic shock syndrome, given the clinical appearance of septic shock with no positive blood cultures. The characteristic diffuse rash, as well as the lack of a primary infected site, make Staphylococcus the most likely inciting agent. Streptococcal toxic shock usually has a prominent primary site of infection, but the diffuse rash is usually much more subtle than in this case. Staphylococcal toxic shock can be associated with immunosuppression, surgical wounds, or retained tampons. Mere Staphylococcus aureus colonization (with an appropriate toxigenic strain) can incite toxic shock. Centers for Disease Control and Prevention guidelines state that measles, Rocky Mountain spotted fever, and leptospirosis need to be ruled out serologically to confirm the diagnosis. However, this patient is at very low risk for these diagnoses based on vaccination and travel history. Juvenile rheumatoid arthritis would become a consideration only if the fevers were more prolonged and there was documented evidence of organomegaly and enlarged lymph nodes.

I-73. The answer is C. (Chap. 17) Although he never underwent joint fluid sampling, the presentation of monoarticular arthritis of the great toe in the context of a patient taking diuretics makes gout very likely. Allopurinol, although effective at controlling hyperuricemia, is a frequent culprit in drug-induced hypersensitivity syndromes. This syndrome generally presents with evidence of systemic hypersensitivity, including rash, eosinophilia, and often renal or hepatic dysfunction. Desquamative erythroderma and toxic epidermal necrolysis have been described additionally with allopurinol, but the absence of mucous membrane involvement makes TEN less likely. The absence of preexisting septic arthritis makes toxic shock less likely. Angioedema is not known to be associated with diffuse erythroderma. Diffuse erythema is not a feature of bacterial endocarditis, which frequently has associated focal skin lesions such as Osler lesions or Janeway nodes. Finally, in the absence of a focal area of infection, MRSA cellulitis would not explain the findings.

I-74. The answer is C. (Chap. 18) Fever of unknown origin (FUO) is defined as the presence of fevers to greater than 38.3°C (101.0°F) on several occasions occurring for more than 3 weeks without a defined cause after appropriate investigation into potential causes have failed to yield a diagnosis. Initial laboratory investigation into an FUO should include a complete blood count with differential, peripheral blood smear, ESR, C-reactive protein, electrolytes, creatinine, calcium, liver function tests, urinalysis, and muscle enzymes. In addition, specific testing for a variety of infections should be performed, including VDRL for syphilis, HIV, CMV, EBV, PPD testing, and blood, sputum, and urine cultures if appropriate. Finally, the workup should include evaluation for inflammatory disorders. These tests include antinuclear antibodies, rheumatoid factor, ferritin, iron, and transferrin. This patient has had a significant workup that has demonstrated primarily nonspecific findings, including elevation in the erythrocyte sedimentation rate and ferritin as well as borderline enlargement of multiple lymph nodes. The only finding that may help define further workup is the elevation in calcium levels. When combined with the clinical symptoms and prominent lymph nodes, this could suggest granulomatous diseases, including disseminated tuberculosis, fungal infections, or sarcoidosis. The next step in the work up of this patient would be to obtain a sample from an enlarged lymph node for cultures and pathology to confirm granulomatous inflammation and provide additional samples for microbiology. In recent studies, up to 30% of individuals will not have an identified cause of FUO, and infectious etiologies continue to comprise 25% of all FUO. The most common infection causing FUO is extrapulmonary tuberculosis, which may be difficult to diagnose because PPD is often negative in these individuals. However, one would not consider empirical therapy if the possibility to obtain definitive diagnosis exists through a procedure such as a needle biopsy because it is prudent to have not only the diagnosis but also the sensitivity profile of the organism to ensure appropriate therapy. Even in the presence of granulomatous infection, sarcoidosis would be considered a diagnosis of exclusion and would require definitive negative mycobacterial cultures before considering therapy with corticosteroids. Serum angiotensin-converting enzyme levels are neither appropriately sensitive nor specific for diagnosis of sarcoidosis and should not be used to determine if therapy is needed. PET-CT imaging would be unlikely to be helpful in this situation because the presence of granulomatous inflammation can lead to false-positive results or will confirm the presence of already characterized abnormal lymph nodes.

I-75. The answer is D. (Chap. 19) When evaluating a patient with hypothermia, it is important to consider all the possible factors that could contribute to hypothermia because treatment of hypothermia alone without treating the underlying cause could lead to delayed diagnosis and poor outcomes. In some instances, it is clear that the cause of hypothermia is simply prolonged exposure to cold without proper clothing. However, in patients such as this one, the clinician will need to look for findings that would be unexpected in a patient with hypothermia. This patient has a moderate degree of hypothermia (between 28.0°C and 32.2°C). At this range of hypothermia, the expected clinical presentation would be one of a global slowing of metabolism. Clinically, this would include a depressed level of consciousness with papillary dilatation. Often, these individuals experience a paradoxical instinct to take off their clothes. In addition, the heart rate, blood pressure, and respiratory rate would be expected to decrease. Carbon dioxide production by tissues typically decreases by 50% for each 8°C drop in body temperature. A common error in the treatment of individuals with hypothermia is overly aggressive hyperventilation in the face of this known decrease in carbon dioxide production. In this patient, despite the hypothermia there is an increased respiratory rate in the setting of a metabolic acidosis. This finding suggests a lesion in the central nervous system or ingestion of an alcohol that

would lead to a metabolic acidosis. Ingestion is confirmed by the presence of a very high anion gap (28) as well as an osmolar gap. The osmolar gap can be calculated as (Sodium × 2) + (BUN/2.8) + (Glucose/18) + (Ethanol/4.6). In this patient, the calculated osmolarity would be 301.6. Thus, the osmolar gap is 26, indicating the presence of some other osmotically active compound. In this case, it is prudent to measure toxic alcohol levels such as methanol and ethylene glycol. In the management of the patient’s hypothermia, warmed intravenous fluids may be indicated. However, lactated Ringer’s solution should be avoided because the liver may be unable to metabolize lactate and lead to worsening metabolic acidosis. The cardiac complications of hypothermia may lead to bradyarrhythmias, but cardiac pacing is rarely indicated. If required, the transthoracic route is preferred because placement of any leads into the heart may lead to refractory ventricular arrhythmias.

I-76. The answer is B. (Chap. 19) This patient presents with frostbite of the left foot. The most common presenting symptom of this disorder is sensory changes that affect pain and temperature. Physical examination can have a multitude of findings, depending on the degree of tissue damage. Mild frostbite will show erythema and anesthesia. With more extensive damage, bullae and vesicles will develop. Hemorrhagic vesicles are caused by injury to the microvasculature. The prognosis is most favorable when the presenting area is warm and has a normal color. Treatment is with rapid rewarming, which usually is accomplished with a 37–40°C (98.6–104°F) water bath. The period of rewarming can be intensely painful for the patient, and often narcotic analgesia is warranted. If the pain is intolerable, the temperature of the water bath can be dropped slightly. Compartment syndrome can develop with rewarming and should be investigated if cyanosis persists after rewarming. No medications have been shown to improve outcomes, including heparin, steroids, calcium channel blockers, and hyperbaric oxygen. In the absence of wet gangrene or another emergent surgical indication, decisions about the need for amputation or debridement should be deferred until the boundaries of the tissue injury are well demarcated. After recovery from the initial insult, these patients often have neuronal injury with abnormal sympathetic tone in the extremity. Other remote complications include cutaneous carcinomas; nail deformities; and, in children, epiphyseal damage.

I-77. The answer is D. (Chap. 20) Syncope is a common medical complaint that occurs when there is global cerebral hypoperfusion. Syncope accounts for 3% of all emergency department visits and 1% of all hospitalizations. Additionally, it is estimated that 35% of all individuals will experience at least one syncopal event in their lifetimes. The most common cause of syncope in young adults is neurally mediated syncope. The incidence of neurally mediated syncope is higher in females and has a familial predisposition. Neurally mediated syncope represents a complex reflex arc of the autonomic nervous system and inherently requires an intact autonomic nervous system to occur. The final pathway of neurally mediated syncope is a surge of parasympathetic activity with inhibition of the sympathetic nervous system. This results in hypotension with accompanying bradycardia. Syncope occurs when blood flow to the brain drops abruptly. Triggers of the reflex pathway are varied. Vasovagal syncope is one category without a clearly defined trigger but can occur with intense emotions, strong odors, or orthostatic stress. Individuals who faint at the sight of blood experience vasovagal syncope. Neurally mediated syncope can also be brought about by specific situations such as cough, micturition, swallowing, or carotid sensitivity. The primary symptoms of neurally mediated syncope include premonitory symptoms such as lightheadedness and dizziness as well as parasympathetic symptoms such as diaphoresis, pallor, hyperventilation, pallor, and palpitation. Myoclonic jerks of the extremities can occur and be difficult to distinguish from seizure activity. On rare occasions, an individual may

experience urinary incontinence, but fecal incontinence does not occur. Individuals usually recover very quickly from neurally mediated syncope with a rapid return to consciousness and previous level of alertness. Reassurance and avoidance of triggers are the primary treatments. Liberal intake of fluids and salt expand plasma volume and are protective against syncopal events. In randomized controlled trials, isometric counterpres-sure maneuvers (leg crossing or handgrip) are also protective. In patients with refractory syncope, fludrocortisone, beta-blockers, or vasoconstricting agents have been used with clinical success, although there are no clinical trial data to support their use.

I-78. The answer is A. (Chap. 20) The cornerstone of the evaluation of syncope is to perform an thorough history and examination. Clues to the cause of syncope include the presence of prodromal symptoms, presence of injury, and eyewitness accounts of the event. Neurally mediated syncope is one of the most common causes of syncope and often has preceding lightheadedness or dizziness. Orthostatic hypotension is also frequently preceded by symptoms of lightheadedness and is more common in older individuals. Likewise, older individuals are at greater risk of cardiac syncope. Cardiac syncope needs to be considered as cardiac syncope caused by structural heart disease or primary arrhythmia is associated with an increased risk of sudden cardiac death. Cardiac syncope is more likely to occur without warning symptoms and is more likely to have associated serious injury. Hypoglycemia can present with syncope as well and needs to be considered in this case. Neurologic causes of syncope include seizures and vertebrobasilar insufficiency. A cerebrovascular accident does not commonly cause syncope because bihemispheric disruption of cerebral blood flow is necessary to cause loss of consciousness.

In this individual, evaluation should include fingerstick glucose measurement, orthostatic blood pressures, and an electrocardiogram. Tilt table testing can be considered, particularly because the patient has had recurrent episodes of syncope in the past. A head CT scan, however, should not be a routine part of the evaluation of syncope unless there is concern about a head injury that occurred as a result of the syncope.

I-79. The answer is D. (Chap. 21) Dizziness is a common complaint affecting approximately 20% of the population over the course of the year. Most dizziness is benign, self-limited, and must be distinguished from vertigo. Although dizziness is often described as a sensation of lightheadedness, vertigo is more often described as a sensation that the room is spinning. Vertigo is most commonly from peripheral causes affecting labyrinths of the inner ear or the vestibular nerve. However, central lesions of the brainstem and cerebellum can also lead to vertigo. Features of the history and physical examination can be useful in determining central versus peripheral causes of vertigo. By history, deafness or tinnitus is typically absent with central lesions. On physical examination, spontaneous nystagmus is most often a sign of central vertigo, although it can be seen with acute vestibular neuritis. Specific patterns of vertigo that are characteristic of lesions in the cerebellar pathways are vertical nystagmus with a downward fast phase (downbeat nystagmus) and horizontal nystagmus that changes direction with gaze (gaze-evoked nystagmus). Alternatively, in peripheral vertigo, nystagmus typically is provoked by positional maneuvers and can be inhibited by visual fixation. Visual fixation does not, however, inhibit nystagmus in central lesions. Finally, central causes of nystagmus are more likely to be associated with other symptoms that would lead one to suspect a central cause. These include hiccups, diplopia, cranial neuropathies, and dysarthria.

I-80. The answer is C. (Chap. 21) The symptoms and physical examination of this patient are typical of

benign paroxysmal positional vertigo (BPPV). Episodes of BPPV are typically quite brief, lasting no more than 1 minute, and are brought about by changes in position relative to gravity. Typical movements that elicit the vertigo are lying down, rolling over in bed, rising from the supine position, and tilting the head to look upward. The labyrinth of the inner ear is responsible for process information with regards to position and movement. It consists of three semicircular canals: the superior canal, the posterior canal, and the horizontal canal. BPPV results when calcium carbonate crystals called otoconia migrate from the utricle of the inner ear into the semicircular canals. By far, the most commonly affected canal is the posterior one. When this occurs, vertigo is accompanied by nystagmus that beats upward and torsionally toward the affected ear. This can be brought about by the Dix-Hallpike maneuver, which is described in the clinical scenario. Less commonly, the horizontal canal is affected, leading to horizontal nystagmus. The primary treatment of BPPV is repositioning therapy that uses gravity to remove the otoconia from the affected canal. The Epley maneuver is the most common repositioning procedure. The history and physical examination are not consistent with a central cause of vertigo; therefore, a brain MRI is not indicated. Methylprednisolone is the primary treatment of acute vestibular neuritis if used within the first 3 days of symptoms. Acute vestibular neuritis often presents with more prolonged symptoms that persist even when there is no movement of the head. Most patients recover spontaneously, but when used early, methylprednisolone will decrease the duration of symptoms. There is no indication for the use of antiviral therapy unless there is obvious herpes zoster infection. Likewise, the symptoms are not consistent with migrainous vertigo, which would be persistent for hours and not be affected by positional changes. Thus, the use of rizatriptan would not be helpful.

I-81. The answer is D. (Chap. 22) Complaints of weakness in a patient have a multitude of causes, and it is important to perform a thorough history and physical examination to help localize the site of weakness. Lower motor neuron diseases occur when there is destruction of the cell bodies of the lower motor neurons in the brainstem or the anterior horn of the spinal cord. Lower motor neuron diseases can also occur because of direct axonal dysfunction and demyelination. The primary presenting symptoms are those of distal muscle weakness such as tripping or decreased hand grip strength. When a motor neuron becomes diseased, it may discharge spontaneously, leading to muscle fasciculations that are not seen in disease of the upper motor neurons or myopathies. Additionally, on physical examination, lower motor neuron disease leads to decreases in muscle tone and decreased or absent deep tendon reflexes. Over time, severe muscle atrophy can occur. A Babinski sign should not be present. If there is evidence of a Babinski sign in the presence of lower motor neuron disease, this should raise the suspicion of a disorder affecting both upper and lower motor neurons such as amyotrophic lateral sclerosis.

I-82. The answer is E. (Chap. 24) Approximately 15% of individuals older than 65 years have an identifiable gait disorder. By age 80 years, 25% of individuals require a mechanical aid to assist ambulation. Proper maintenance of gait requires a complex interaction between central nervous system centers to integrate postural control and locomotion. The cerebellum, brainstem, and motor cortex simultaneously process information regarding the environment and purpose of the motion to allow for proper gait and avoidance of falls. Any disorder affecting either sensory input regarding the environment or central nervous system output has the potential to affect gait. In most case series, the most common cause of gait disorders is a sensory deficit. The causes of sensory deficits can quite broad and include peripheral sensory neuropathy from a variety of causes, including diabetes mellitus, peripheral vascular disease, and vitamin B₁₂ deficiency, among many others. Other common causes of

gait disorders include myelopathy and multiple cerebrovascular infarcts. Although Parkinson’s disease

is almost inevitably marked by gait abnormalities, it occurs less commonly in the general population than the previously discussed disorders. Likewise, cerebellar degeneration is frequently associated with gait disturbance but is a less common disorder in the general population.

I-83. The answer is B. (Chap. 24) Characteristics found during the neurologic examination can assist with the localization of disease in gait disorders. In this case, the patient presents with signs of a frontal gait disorder or parkinsonism. The specific characteristics that would be seen with a frontal gait disorder are a wide-based stance with slow and short shuffling steps. The patient may have difficulty rising from a chair and has a slow, hesitating start. Likewise, there is great difficult with turning with multiple steps required to complete a turn. The patient has very significant postural instability. However, cerebellar signs are typically absent. Romberg sign may or may not be positive, and seated cerebellar testing results are normal, including heel-to-shin testing and rapid alternating movements. Additionally, there should otherwise be normal muscle bulk and tone without sensory or strength deficits. The most common cause of frontal gait disorders (sometimes known as gait apraxia) is cerebrovascular disease, especially small vessel subcortical disease. Communicating hydrocephalus also presents with a gait disorder of this type. In some individuals, the gait disorder precedes other typical symptoms such as incontinence or mental status change.

Alcoholic cerebellar degeneration and multiple system atrophy present with signs of cerebellar ataxia. Characteristics of cerebellar ataxia include a wide-based gait with variable velocity. Gait initiation is normal, but the patient is hesitant during turns. The stride is lurching and irregular. Falls are a late event. The heel-to-shin test is abnormal, and the Romberg test is variably positive. Neurosyphilis and lumbar myelopathy are examples of sensory ataxia. Sensory ataxia presents with frequent falls. The gait with sensory ataxia, however, is narrow based. Often the patient is noted to be looking down while walking. The patient tends to walk slowly but have path deviation. Gait is initiated normal, but the patient may have some difficulty with turning. The Romberg test is typically unsteady and may result in falls.

I-84. The answer is D. (Chap. 25) Delirium is an acute confusional state that most frequently occurs in the context of an acute medical illness. Fluctuating levels of cognitive function with a particular deficit of attention are the primary clinical features of delirium. All levels of cognitive function, however, are invariably involved, including memory, language, and executive functioning. Other common associated symptoms are sleep–wake disturbances, hallucinations or delusions, affect changes, and changes in heart rate or blood pressure. Delirium remains a clinical diagnosis and is believed to affect as much as 50% of hospitalized patients. For elderly patients in intensive care, the incidence rises to between 70 and 87%. However, it has been estimated the diagnosis is missed in one-third of individuals with delirium. Once thought of as an acute but benign condition, increasing research is demonstrating delirium to have persisting effects on cognition and functioning. Delirium typically is short lived, but some episodes of delirium can last for weeks, months, or even years. When delirium persists for longer periods of time, it is thought to represent inadequate treatment of the cause of delirium or permanent neuronal damage from the episode. Delirium also has significant associated morbidity and mortality. A single episode of delirium in hospitalized patients has been associated with an in-hospital mortality rate as high as 25–33%. However, the increased mortality is not simply limited to the hospital stay. Individuals experiencing delirium in the hospital have increased mortality for the next several months to years. In addition, these individuals experience a longer hospital length of stay and are less likely to return to functional independence. Individuals who experience delirium are more likely to be

discharged to nursing home care and are at increased risk of rehospitalization.

I-85. The answer is B. (Chap. 25) This patient has features of acute delirium, which can be precipitated by many causes in hospitalized patients. Broad categories of causes of delirium include toxins, medication reactions, metabolic disorders, infections, endocrine disorders, cerebrovascular disorders (especially hypertensive encephalopathy), autoimmune disorders, seizures, neoplastic disorders, and hospitalization. Although the list of causes is broad, the initial history and physical examination are important to establish potential etiologies of delirium and guide further workup. In most patients with delirium, it is difficult to obtain an accurate history; therefore, it is important to seek out a spouse of family member to outline the history further. In this case, there are features that could suggest alcohol withdrawal (hypertension, tachycardia, fevers, tremors), and one should clarify his alcohol intake with his wife. Another primary consideration in determining the etiology of a delirium episode is the time course over which it evolves and the current medications. Particularly in older hospitalized individuals, common medications used as sleep aids, such as diphenhydramine, can have a paradoxical effect with delirium and agitation. It is estimated that as many as one-third of episodes of delirium in hospitalized patients are the result of medications. Worsening infection also needs to be considered because the change in the patient’s vital signs could be indicative of an infectious source, although the elevated blood pressure is not consistent with this. Because the patient has required oxygen during his hospitalization, it is important to check an oxygen saturation or arterial blood gas because acute hypoxemia or hypercarbia can precipitate delirium. Likewise, given the patient’s history of diabetes mellitus, a fingerstick glucose is necessary because hypoglycemia could also lead to alterations in mental status with evidence of tachycardia, tremor, and diaphoresis. Other initial tests to consider in an individual with delirium are electrolytes and basic liver and kidney function. Although commonly ordered, brain imaging is most often not helpful in the evaluation of delirium.

I-86. The answer is C. (Chap. 25) Confusion is defined as a mental and behavioral state of reduced comprehension, coherence, and capacity to reason. Delirium is used to describe an acute confusional state. Delirium often goes unrecognized despite clear evidence that it is often a cognitive manifestation of many medical and neurologic illnesses. Delirium is a clinical diagnosis that may be hyperactive (e.g., alcohol withdrawal) or hypoactive (e.g., opiate intoxication). There is often dramatic fluctuation between states. Delirium is associated with a substantial mortality rate with in-hospital mortality estimates ranging from 25–33%. Overall estimates of delirium in hospitalized patients range from 15– 55% with higher rates in elderly adults. Patients in the intensive care unit have especially high rates of delirium, ranging from 70–87%. The clinic setting represents the lowest risk. Postoperative patients, especially after hip surgery, have an incidence of delirium that is somewhat higher than patients admitted to the medical wards.

I-87. The answer is B. (Chap. 26) When evaluating someone who reports difficulty with language, it is important to assess speech in several different domains, which are spontaneous speech, comprehension, repetition, naming, reading, and writing. Anomia refers to the inability to name common objects and is the most common finding in patients with aphasia. Indeed, anomia is present in all types of aphasia except pure word deafness or pure alexia. Anomia can present in many fashions, including complete an inability to name, provision of a related word (“pen” for “pencil”), a description of the word (“a thing for writing”), or the wrong word. Fluency is assessed by listening to spontaneous speech. Fluency is decreased in Broca’s or global aphasia but is relatively preserved in other forms of aphasia.

Comprehension is assessed by asking patients to follow conversation and provide simple answers (yes/no, pointing to appropriate objects). The most common aphasia presenting with deficits of comprehension is Wernicke’s aphasia in which fluent but nonsensical spontaneous speech (word salad) is present. Repetition asks patients to repeat a string of words, sentences, or a single word and is impaired in many types of aphasia. In addition, repetition of tongue twisters can be useful in the evaluation of dysarthria or palilalia as well. Alexia refers to the inability to read aloud or comprehend written language.

Date: 2016-04-22; view: 507