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Project - USMLE Step 3 > Symptom To Diagnosis - Low Back Pain > Flashcards

Symptom To Diagnosis - Low Back Pain Flashcards

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USMLE® Step 1 flashcards
1
Q

Back pain due to disorders of the musculoskeletal structures - Non specific back pain:

A
  1. In general, a specific anatomic diagnosis cannot be made, and there is no definite relationship between anatomic findings and symptoms.
  2. No neurologic signs and symptoms.
  3. Non progressive.
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2
Q

Examples of non specific musculoskeletal back pain:

A
  1. Lumbar strain and sprain.
  2. Degenerative processes of disks and facets.
  3. Spondylolisthesis (anterior displacement of a vertebra on the one beneath it).
  4. Spondylolysis (defect in the pars interarticularis of the vertebra).
  5. Scoliosis.
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3
Q

Specific musculoskeletal back pain:

A
  1. A specific anatomic diagnosis can often be made.
  2. Neurologic signs and symptoms.
  3. Can be progressive.
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4
Q

Examples of specific musculoskeletal back pain:

A
  1. Herniated disk.
  2. Spinal stenosis.
  3. Cauda equina syndrome.
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5
Q

Back pain due to SYSTEMIC disease affecting the spina - Serious, requiring specific and often rapid treatment:

A
  1. Neoplasia - MM, metastasis, lymphoma/leukemia, spinal cord tumors, primary vertebral tumors.
  2. Infection - Osteomyelitis, septic diskitis, paraspinal abscess, epidural abscess.
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6
Q

Back pain due to SYSTEMIC disease affecting the spine - Serious, requiring treatment but not immediately:

A
  1. Osteoporotic compression fracture.

2. Inflammatory arthritis - Ank. spondylitis, psoriatic arthritis, IBD arthritis, Reiter.

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7
Q

Back pain due to VISCERAL disease is serious and often requires specific and rapid diagnosis and treatment:

A
  1. Retroperitoneal - Aortic aneurysm, retroperitoneal adenopathy or mass.
  2. Pelvic - Prostatitis, endometriosis, PID.
  3. Renal - Nephrolithiasis, pyelonephritis, perinephric abscess.
  4. GI - Pancreatitis, cholecystitis, penetrating ulcer.
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8
Q

Hip flexion:

A

Ilio-psoas L2, L3.

Direct nerve supply and femoral twigs.

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9
Q

Knee extension:

A

Quadriceps - L2, L3, L4

Femoral nerve.

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10
Q

Hip extension:

A

Glutei L4, L5

Gluteal nerves.

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11
Q

Knee flexion:

A

Hamstrings L5, S1

Tibial nerve, peroneal nerve. Lateral head of biceps femoris only.

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12
Q

Hip adduction:

A

Glutei and tensor fascia lata L4, L5.

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13
Q

Hip adduction:

A

Adductor group L2, L3, L4

Obturator nerve.

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14
Q

Plantar flexion:

A

S1, S2 tibial nerve - gastrocnemii (tibialis posterior).

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15
Q

Inversion of the foot:

A

L4 - Tibial and peroneal nerves. (Tibialis anterior, an anterior compartment muscle, and tibialis posterior, a posterior compartment muscle, work together).

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16
Q

Dorsiflexion:

A

L4, L5 - Peroneal nerve (Tibialis anterior, long extensors, peroneus tertius, extensor digitorum brevis).

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17
Q

Eversion of the foot:

A

S1 - Peroneal nerve (peronei longus and brevis, long extensors assist, extensor digitorum brevis).

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18
Q

Low back pain evaluation - 1st step:

A 
Is there any:
1. Urinary retention/incontinence.
2. Leg weakness.
3. Saddle anesthesia.
IF YES --> IMMEDIATE MRI TO RULE OUT CAUDA EQUINA SYNDROME.
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19
Q

Low back pain approach - If there is NO symptoms/signs of cauda equina syndrome - 2nd step:

A
  1. Sciatica.
  2. History of cancer.
  3. Osteoporosis risk factors.
  4. Fever/IVDA/Immunosuppression/Skin infection/Instrumentation.
  5. Wide-based gait, thigh pain/ older patient.
    IF NOT any of the above –> Mechanical low back pain –> Treat conservatively.
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20
Q

Low back pain approach - If sciatica?

A

Consider herniated disk; treat conservatively –> If NO RESPONSE –> MRI; consider epidural injection or surgery.

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21
Q

Low back pain approach - If history of cancer:

A

Spine radiograph or MRI to look for vertebral metastasis.

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22
Q

Low back pain approach - Osteoporosis risk factors:

A

Spine radiograph to look for osteoporotic compression fracture.

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23
Q

Low back pain approach - Fever/IVDA/Immunosuppression/Skin infection/instrumentation?

A

MRI to look for spinal epidural abscess or vertebral osteomyelitis.

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24
Q

Low back pain approach - Wide-based gait, thigh pain, older patient:

A

Vascular risk factors?
YES –> Conservative therapy for presumed spinal stenosis/ Consider MRI to confirm diagnosis/ perform ABIs to look for PAD.
NO –> Conservative therapy for presumed spinal stenosis/ Consider MRI to confirm diagnosis.

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25
Q

Mechanical low back pain - Textbook presentation:

A

The classic presentation is non radiating pain and stiffness in the lower back, often precipitated by heavy lifting.

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26
Q

Mechanical low back pain - Disease highlights:

A
  1. May have pain and stiffness in the buttocks and hips.
  2. Generally occurs hours to days after a new or unusual exertion and improves when the patient is supine.
  3. Can rarely make a specific anatomic diagnosis.
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27
Q

Mechanical low back pain - Prognosis:

A

75-90% of patients improve within 1 month.

25-50% have additional episodes over the next year.

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28
Q

Mechanical low back pain - Risk factors for persistent low back pain:

A
  1. History of previous back pain.
  2. Depression.
  3. Substance abuse.
  4. Pending or past litigation or disability compensation.
  5. Low socioeconomic status.
  6. Work dissatisfaction.
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29
Q

What is important to keep in mind about imaging studies in the approach of low back pain?

A

Many ASYMPTOMATIC patients will have anatomic abnormalities on imaging studies.

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30
Q

…% of patients aged 14-25 have degenerative disks on plain radiographs:

A

20%.

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31
Q

…-…% of patients <50 have herniated disks on MRI:

A

20-75%.

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32
Q

…-…% of patients have bulging disks on MRI.

A

40-80%.

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33
Q

Over …% of patients >50 have degenerative disks on MRI:

A

90%.

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34
Q

Up to …% of patients >50 have spinal stenosis:

A

20%.

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35
Q

Bottom line about imaging studies in low back pain:

A

Patients who have none of the clinical clues should NOT have any diagnostic testing done.

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36
Q

ACUTE low back pain - Treatment:

A
  1. NSAIDS + muscle relaxants are effective.
  2. Heat and spinal modulation have been shown to reduce ACUTE low back pain.
  3. Best approach - NSAIDs and heat during the acute phase and activity as tolerated until the pain resolves.
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37
Q

ACUTE low back pain and bed rest:

A

Does NOT help acute pain and may prolong duration of pain.

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38
Q

Subacute or chronic low back pain - Treatment:

A
  1. TCAs.
  2. Tramadol.
  3. Opioids.
  4. Gabapentin.
  5. Benzodiazepines.
    Best evidence is for TCAs.
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39
Q

Herniated disk - Textbook presentation:

A

Moderate to severe pain radiating from the back down the buttock and leg, usually to the foot or ankle, with associated numbness or paresthesias –> Called sciatica.

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40
Q

Sciatica is classically precipitated by?

A

A sudden increase in pressure on the disk, such as after coughing or lifting.

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41
Q

Herniated disk - Disk disease is frequently?

A

ASYMPTOMATIC.

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42
Q

Herniated disk - MC site of weakness:

A

Foot plantar or dorsiflexion.

Proximal weakness suggests a femoral neuropathy or compression of the lumbar plexus.

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43
Q

Herniated disk - Highest prevalence:

A

In the 45-64yrs old age group.

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44
Q

Herniated disk - Risk factors:

A
  1. Sedentary activities, especially driving.
  2. Chronic cough.
  3. Lack of physical exercise.
  4. Possibly pregnancy.
    - -> Jobs involving lifting and pulling have NOT been associated with increased risk.
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45
Q

Herniated disk - Prognosis:

A

50% –> Recover in 2 weeks.

70% –> Recover in 6 weeks.

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46
Q

Which spinal levels are involved in herniated disks:

A

L4-L5 and L5-S1 cause 98% of clinically important disk herniations, so pain and paresthesias are often seen in these distributions.

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47
Q

What is important to keep in mind regarding UNILATERAL disk?

A

There are NO bowel or bladder symptoms with UNILATERAL disk herniations.

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48
Q

Herniated disk - What may aggravate pain?

A

Coughing, sneezing, or prolonged sitting.

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49
Q

BILATERAL midline herniations can cause the?

A

Cauda equina syndrome.

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50
Q

Cauda equina syndrome - Features:

A
  1. Urinary retention - Sens 90%, spec 95%, LR+=18, LR-=0.1.
  2. Urinary incontinence.
  3. Decr. anal sphincter tone (80%).
  4. Sensory loss in a saddle distribution (75%).
  5. Bilateral sciatica.
  6. Leg weakness.
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51
Q

Suspected cauda equina syndrome is?

A

A MEDICAL EMERGENCY - Requires immediate imaging and decompression.

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52
Q

Sciatica has an LR+ of … for the diagnosis of L4-L5 or L5-S1 herniated disk.

A

7.9

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53
Q

A positive straight leg test reproduces patients sciatica when the leg is elevated between … and … degrees.

A

30 and 60 degrees.

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54
Q

Sciatica pain description:

A

Shooting down the leg, not just a pulling sensation in the hamstring muscle.

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55
Q

Crossed straight leg test:

A

Is performed by lifting the contralateral leg; a positive test reproduces sciatica in the affected leg.

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56
Q

A straight leg test that elicits back pain is:

A

NEGATIVE.

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57
Q

Physical exam findings for the diagnosis of disk herniation - Sciatica:

A

Sens - 95%.
Spec - 88%.
LR+: 7.9.
LR-: 0.06.

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58
Q

Positive crossed straight leg raise for the diagnosis of disk herniation:

A

Sens - 25%.
Spec - 90%.
LR+ 2.5.
LR- 0.83.

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59
Q

Positive ipsilateral straight leg raise for the diagnosis of herniated disk:

A

Sens - 91%.
Spec - 26%.
LR+: 1.2.
LR-: 0.3.

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60
Q

Ankle dorsiflexion weakness for the diagnosis of herniated disk:

A

Sens - 35%.
Spec - 70%.
LR+: 1.2.
LR-: 0.93.

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61
Q

Great toe extensor weakness for the diagnosis of disk herniation:

A

Sens - 50%.
Spec - 70%.
LR+: 1.7.
LR-: 0.71.

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62
Q

Impaired ankle reflex for the diagnosis of disk herniation:

A

Sens - 50%.
Spec - 60%.
LR+: 1.3.
LR-: 0.83.

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63
Q

Ankle plantar flexion weakness for the diagnosis of disk herniation:

A

Sens - 6%.
Spec - 95%.
LR+: 1.2.
LR-: 0.99.

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64
Q

Herniated disk - Plain radiographs:

A

Do NOT image the disks and are USELESS for diagnosing herniations.

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65
Q

CT and MRI scans for diagnosing herniated disks:

A

CT –> Sens 62-90%, spec 70-87%, LR+ 2.1-6.9, LR- 0.11-0.54.

MRI –> Sens 60-100%, spec 43-97%, LR+ 1.1-33, LR- 0-0.93.

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66
Q

Herniated disk - In the absence of cauda equina syndrome or progressive neurologic dysfunction, what should be tried?

A

Conservative therapy for 1 month.

  1. NSAIDs are the 1st choice.
  2. Opioids are necessary.
  3. Bed rest does NOT accelerate recovery.
  4. Epidural corticosteroid injections may provide temporary pain relief.
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67
Q

Herniated disk - Surgery indications include:

A
  1. Impairment of bowel and bladder function (cauda equina syndrome).
  2. Gross motor weakness.
  3. Progressive neurologic symptoms or signs.
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68
Q

Back pain due to metastatic cancer - Textbook presentation:

A

The classic presentation is the development of constant, dull back pain that is not relieved by rest and is worse at night in a patient with a known malignancy.

69
Q

Bone Metastases can be limited?

A

To the vertebral body, or extend into the epidural space, causing cord compression.

70
Q

Cancer + back pain + neurologic abnormalities = ?

A

EMERGENCY.

71
Q

Malignancy causes about …% of back pain in general but is the cause in nearly all patients with cancer who have back pain.

A

1%.

72
Q

MC sources of bone metastases:

A
  1. Breast.
  2. Prostate.
  3. Lung.
73
Q

Thoracic or lumbar vertebrae are affected?

A

In most cases –> Thoracic.

Prostate metastases involve the lumbar vertebrae.

74
Q

Osteoblastic lesions:

A
  1. Prostate.
  2. Small cell lung cancer.
  3. Hodgkin.
75
Q

Osteolytic lesions:

A
  1. Renal cell.
  2. Myeloma.
  3. NHL.
  4. Melanoma.
  5. Non small cell lung carcinoma.
  6. Thyroid.
76
Q

Mixed osteoblastic and osteolytic lesions:

A
  1. Breast cancer.

2. GI cancer.

77
Q

History and physical exam - Previous history of cancer:

A

Sens - 31%.
Spec - 98%.
LR+: 14.7.
LR-: 0.7.

78
Q

History and physical exam - Failure to improve after 1 month of therapy:

A

Sens - 31%.
Spec - 90%.
LR+: 3.0
LR-: 0.77.

79
Q

History and physical exam - Age >50.

A

Sens - 77%.
Spec - 71%.
LR+: 2.7.
LR-: 0.32.

80
Q

History and physical exam - Unexplained weight loss:

A

Sens - 15%.
Spec - 94%.
LR+: 2.7.
LR-: 0.9.

81
Q

History and physical exam - Duration of pain >1month:

A

Sens - 50%.
Spec - 81%.
LR+: 2.6.
LR-: 0.62.

82
Q

History and physical exam - No relief with bed rest:

A

Sens - 90%.
Spec - 46%.
LR+: 1.7.
LR-: 0.21.

83
Q

Back pain due to metastatic cancer - Plain radiographs:

A

Sens - 60%.
Spec - 96-99.6%.
LR+: 12-120.
LR-: 0.4-0.42.
–> Must lose about 50% of trebecular bone before a lytic lesion is visible.
–> Blastic lesions can be seen earlier on radiographs than lytic lesions.

84
Q

Back pain due to metastatic cancer - CT scan:

A

Sensitivity and specificity for diagnosing metastatic lesions are unknown.

85
Q

Back pain due to metastatic cancer - MRI:

A

Sens - 83-93%.
Spec - 90-97%.
LR+: 8.3-31.
LR-: 0.07-0.19.

86
Q

Back pain due to metastatic cancer - Bone scan:

A

Sens - 74-98%.
Spec - 64-81%.
LR+: 3.9-10.
LR-: 0.1-0.32.

87
Q

Bone scan is better for lytic or for blastic lesions:

A

For blastic lesions than lytic - Myeloma, in particular, can be missed on bone scan.

88
Q

What is the best test for diagnosing or ruling out cancer as a cause of back pain and for determining whether there is cord compression.

A

MRI scan.

89
Q

Back pain due to metastatic cancer - Treatment:

A
  1. Surgery/Radiation/Chemotherapy.

2. Choice of therapy depends on the type of cancer and the extent of the lesion.

90
Q

Osteoporotic compression fracture - Textbook presentation:

A

Acute, severe pain that develops in an older woman and radiates around the flank to the abdomen, occurring either spontaneously or brought on by trivial activity such as minor lifting, bending, or jarring.

91
Q

Osteoporotic fractures are usually?

A

Mid to lower thoracic or lumbar region.

92
Q

Fractures at T4 or higher are more often due to?

A

Malignancy than osteoporosis.

93
Q

In osteoporosis, pain is often?

A

Increased by slight movements, such as turning over in bed.

94
Q

Pain from osteoporotic fracture usually improves within?

A

1 week and resolves by 4-6weeks, but some patients have more chronic pain.

95
Q

Osteoporosis is most commonly related to?

A

Menopause and aging - Primary.

96
Q

Osteoporosis may be secondary to?

A
  1. Thyrotoxicosis.
  2. Primary hyperparathyroidism.
  3. Vit D def.
  4. Hypogonadism.
  5. Malabsorption.
  6. Medications - steroids.
97
Q

Main risk factor for atherosclerosis:

A

Age - RR of almost 10 for women aged 70-74 (compared with women under 65).
RR of 22.5 for women over 80.

98
Q

Other risk factors for osteoporosis:

A
  1. Personal history of rib, spine, wrist, or hip fracture.
  2. Current smoking.
  3. White, Hispanic, or Asian ethnicity.
  4. Weight <132lbs.
  5. Family history of osteoporosis.
99
Q

Risk of developing osteoporosis is decreased in?

A
  1. Women who are obese.
  2. Are of African American descent.
  3. Estrogen postmenopausally.
100
Q

Osteoporosis compression fracture - History and physical exam:

A
  1. Not well studied.
  2. Age >70 has LR+ of 5.5.
  3. History of steroids has LR+ of 12.0 for diagnosis of osteoporotic compression fracture as a cause of back pain.
101
Q

Osteoporotic compression fracture - Imaging:

A 
Best way is MRI to distinguish malignant from benign osteoporotic compression fractures.
Sens - 88.5-100%
Spec - 89.5-93%.
LR+: 8-14.
LR-: 0-0.12.
102
Q

Spinal stenosis - Textbook presentation:

A

The classic presentation is somewhat vague, but persistent back and leg discomfort brought on by walking or standing that is relieved by sitting or bending forward.

103
Q

Pain from spinal stenosis:

A

Symptoms are usually bilateral and are often described as a heaviness or numbness brought on by standing or walking (“pseudo claudication”).

104
Q

Spinal stenosis is most often seen in?

A

Lumbar spine, sometimes in cervical and rarely in thoracic.

105
Q

Spinal stenosis is due?

A

To hypertrophic degenerative processes and degenerative spondylolisthesis compressing the spinal cord, Cauda equina, individual nerve roots, Arterioles and capillaries supplying the CAUDA equina and nerve roots.

106
Q

In spinal stenosis, pain is?

A

Worsened by extension.

Relieved by flexion.

107
Q

Findings that differentiate vascular from neurogenic claudication?

A

In vascular we have:

  1. Fixed walking distance before symptoms.
  2. Improved by standing still.
  3. Worsened by walking.
  4. Painful to walk uphill.
  5. Absent pulses.
  6. Skin shiny with loss of hair.
108
Q

Spinal stenosis - Wide-based gait:

A

Sens - 43%.
Spec - 97%.
LR+: 14.3.
LR-: 0.59.

109
Q

Spinal stenosis - No pain when seated:

A

Sens - 46%.
Spec - 93%.
LR+: 6.6.
LR-: 0.58.

110
Q

Spinal stenosis - Abnormal Romberg test results:

A

Sens - 39%.
Spec - 91%.
LR+: 4.3.
LR-: 0.67.

111
Q

Spinal stenosis - Symptoms improve when seated:

A

Sens - 52%.
Spec - 83%.
LR+: 3.1.
LR-: 0.58.

112
Q

Spinal stenosis - Vibration deficit:

A

Sens - 53%.
Spec - 81%.
LR+: 2.8.
LR-: 0.58.

113
Q

Spinal stenosis - Age >65:

A

Sens - 77%.
Spec - 69%.
LR+: 2.5.
LR-: 0.33.

114
Q

Spinal stenosis - Pseudoclaudication:

A

Sens - 63%.
Spec - 71%.
LR+: 2.0.
LR-: 0.53.

115
Q

Spinal stenosis - Radiography:

A

Can detect compromise of vertebral foramina by bone but not by soft tissue - Not as sensitive as CT or MRI.

116
Q

Spinal stenosis - CT:

A

Sens - 90%.
Spec - 80-96%.
LR+: 4.5-22.
LR-: 0.10-0.12.

117
Q

Spinal stenosis - MRI:

A

Sens - 90%.
Spec - 72-99%.
LR+: 3.2-90.
LR-: 0.10-0.14.

118
Q

Up to …% of asymptomatic patients over age 65 have spinal stenosis on MRI:

A

21%.

119
Q

Bottom line about CT and MRI in spinal stenosis:

A

They can rule out spinal stenosis but cannot necessarily determine whether visualized stenosis is causing the patients symptoms.

120
Q

Peripheral artery disease - Textbook presentation:

A

Classic claudication is defined as reproducible, exercise-induced calf pain that requires stopping and is relieved with less than 10min of rest.

121
Q

In a study of outpatients over the age of 70, or aged 50-69 with a history of smoking or diabetes, the prevalence of PAD was …%.

A

29%.

122
Q

Only …% of the patients with PAD had classic claudication.
…% of patients had atypical symptoms (Exertional leg pain that was not in the calf or was not relieved by rest).
…% had no leg pain.

A

11%.
47%.
42%.

123
Q

Critical limb ischemia is presenting manifestation in …-…% of patients.

A

1-2%.

124
Q

Risk factors for PAD:

A
  1. Smoking - 1.4 for every 10cig/day.
  2. HTN - 1.5 for mild, 2.2 for moderate HTN.
  3. Diabetes - 2.6.
  4. Hyperlipidemia - 1.2 for each 40mg/dL increase in cholesterol.
125
Q

Pretest probability of PAD - Asymptomatic patients:

A

Age:
60-69 –> 5%.
70-79 –> 12%.

126
Q

Pretest probability of PAD - Asymptomatic patients with stroke:

A

15%.

127
Q

Pretest probability of PAD - Asymptomatic with ischemic heart disease:

A

13%.

128
Q

Pretest probability of PAD - Asymptomatic patient with diabetes:

A

11%.

129
Q

Pretest probability of PAD - Asymptomatic patient with hypercholesterolemia/HTN/Male sex/smoking (current or quit in last 5yrs):

A

HyperCH - 6%.
HTN - 7%.
Male sex - 5%.
Smoking - 7%.

130
Q

Pretest probability of PAD - patient with leg complaints Age 60-80:

A

15%.

131
Q

Pretest probability of PAD - Patient with leg complaints and stroke/ischemic heart disease:

A

Stroke - 26%.

Ischemic heart disease - 19%.

132
Q

Pretest probability of PAD - Patients with leg complaints and diabetes:

A

18%.

133
Q

Pretest probability of PAD - Patients with leg complaints and hyperCH/HTN/male/smoking:

A

15% - HyperCH.
12% - HTN.
12% - Male.
11% - Smoking.

134
Q

The presence of classic claudication has an LR+ of?

A

3.30.

135
Q

The absence of claudication has an LR- of?

A

0.89.

136
Q

Physical exam in claudication - In symptomatic patients, skin being cooler to the touch and the presence of a foot ulcer in the affected leg, both have a LR+ =… and a LR- of about … .

A 
LR+= 5.9.
LR-= 1.0.
137
Q

Are skin changes useful in assessing PAD in ASYMPTOMATIC patients?

A

NOT useful.

138
Q

In symptomatic patients the presence of an iliac, femoral or popliteal bruit has an LR+=… .
The absence of a bruit in ALL three locations has an LR-=… .

A 
LR+= 5.6.
LR-= 0.39.
139
Q

In asymptomatic patients, the finding of a femoral bruit has an LR+=… .

A

4.8.

140
Q

Pulses in claudication - An abnormal femoral pulse has an LR+ of … .
An abnormal posterior tibial pulse has a LR+ of … .

A

Abnormal femoral –> LR+ of 7.2.

Abnormal posterior tibial –> LR+ of 8.1.

141
Q

Abnormal Dorsalis pedis pulse is does NOT increase the probability of PAD (LR+ of 1.9).
Dorsalis pedis pulse is NOT palpable in …% of NORMAL individuals.

A

8.1%.

142
Q

Bottom line about PAD physical findings:

A

Lack of typical symptoms and physical findings does NOT lower the likelihood of PAD.

143
Q

Interpretation of calculated ABI:

A
  1. Above 0.9 –> Normal.
  2. 0.71-0.9 –> Mild.
  3. 0.41-0.70 –> Moderate.
  4. 0-0.40 –> Severe.
144
Q

Spinal epidural abscess - Textbook presentation:

A

A patient with history of diabetes or injection drug use who has fever and back pain, followed by neurological symptoms (motor weakness, sensory changes, bowel and bladder obstruction).

145
Q

Spinal epidural abscess - Predisposing factors:

A
  1. Underlying disease - DM, alcoholism, HIV.
  2. Spinal abnormality or intervention (degenerative joint disease, trauma, surgery, drug injection).
  3. Potential local or systemic source of infection.
146
Q

Spinal epidural abscess - Infection occurs by contiguous spread in …% of cases and by hematogenous spread in …%.

A

33%

50%.

147
Q

Spinal epidural abscess - Causative organisms:

A

66% is S.aureus.

Others - S.epi, E.coli, P.aeruginosa, anaerobes, fungi, mycobacteria, parasites.

148
Q

Spinal epidural abscesses - Clinical manifestations:

A

75% –> Back pain.
50% –> Fever.
33% –> Neurologic deficits.

149
Q

Spinal epidural abscess - More common Posteriorly or anteriorly?

A

Posterior epidural space - And more common in the Thoracolumbar than cervical areas.

150
Q

Spinal epidural abscess - Generally extend over?

A

3-5 vertebrae.

151
Q

Spinal epidural abscess - Staging:

A

Stage 1: Back pain at the level of the affected spine.
Stage 2: Nerve root pain radiating from the involved spinal area.
Stage 3: Motor weakness, sensory deficit, bladder/bowel dysfunction.
Stage 4: Paralysis.

152
Q

Spinal epidural abscess - Most important predictor of the final neurologic outcome:

A

The neurologic status before surgery, with the post-op status being as good as or better than the pre-op status.

153
Q

Spinal epidural abscess - Evidence-based diagnosis:

A
  1. ESR and C-reactive protein are usually elevated.
  2. Leukocytosis in about 66%.
  3. 60% bacteremia.
154
Q

Spinal epidural abscess - Best imaging:

A

MRI with a sensitivity of >90%.

155
Q

Spinal epidural abscess - Treatment:

A
  1. Emergent surgical decompression and drainage.

2. Antibiotics.

156
Q

Vertebral osteomyelitis - Textbook presentation:

A

The classic presentation is unremitting back pain often, but not always, with fever.

157
Q

Vertebral osteomyelitis - Pathogenesis:

A
  1. MC hematogenous spread - can also occur due to contiguous spread or direct infection from trauma or surgery.
  2. Generally causes bony destruction of 2 adjacent vertebral bodies and collapse of the intervertebral space.
158
Q

Vertebral osteomyelitis - Microbiology:

A
  1. S.aureus in over 50%.
  2. Group B and G hemolytic streptococcus, especially in diabetics.
  3. Enteric Gram(-) bacilli, especially after UT instrumentation.
159
Q

Vertebral osteomyelitis - sensitivity of IVDA, UTI, skin infection:

A

40%.

160
Q

Vertebral osteomyelitis - Spinal tenderness:

A

Sens - 86%.
Spec - 60%.
LR+=2.1.
LR-=0.23.

161
Q

Vertebral osteomyelitis - Fever:

A

Sens - 52%.
Spec - 98%.
LR+= 26.
LR-= 0.49.

162
Q

Vertebral osteomyelitis - Leukocytosis:

A

Sens - 43%.
Spec - 94%%.
LR+= 7.2.
LR-= 0.6.

163
Q

Vertebral osteomyelitis - Blood cultures:

A

Positive in 50-70%.

164
Q

Vertebral osteomyelitis - Radiographs:

A

Sens - 82%.
Spec - 57%.
LR+: 1.9.
LR-: 0.32.

165
Q

Vertebral osteomyelitis - MRI:

A

Sens - 96%.
Spec - 92%.
LR+: 12.
LR-: 0.04.

166
Q

Vertebral osteomyelitis - Bone scan:

A

Sens - 90%.
Spec - 78%.
LR+: 4.1.
LR-: 0.13.

167
Q

What should be considered in patients with either vertebral osteomyelitis or a spinal epidural abscess?

A

Endocarditis.

168
Q

Primary task when evaluating a patient with low back pain is?

A

To identify those who have serious causes of back pain that require specific, and sometimes rapid, diagnosis and treatment.

  • -> Serious back pain (systemic, visceral, neurologic origin).
  • -> Non specific back pain (musculoskeletal back pain).

Project - USMLE Step 3 (82 decks)

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