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Differential Diagnosis


									Differential Diagnosis
Presented by M.A. Kaeser, DC
        Winter 2010
   Patients seek physician services for 2
    • To establish the correct diagnosis
    • To obtain the appropriate intervention,
      including prevention
   Treatment provided for an incorrect
    diagnosis fails the patient to the
    same degree as does diagnosis w/o
    appropriate treatment
    Process of Differential Diagnosis
   Diagnosis is obtained after considering a
    number of competitive etiologies and
    progressively eliminating them
   Rational and intuitive skills
   The essence of cost-effective health care
   An orderly approach is necessary
    • Data acquisition, analysis with ranking of
      positive findings, construction of the diff dx,
      narrowing of diff dx by testing strategy
   After diagnosis, therapeutic intervention is
    designed and implemented
               Acquisition of Data
   History and physical exam are the most
    essential components of the diff dx
    • Achieved by intuition and sensory input
    • Verbal and nonverbal clues help formulate the
      tentative diagnostic impressions
          Nonverbal example: oversized clothing from weight
   All diagnostic decisions are dependent
    upon reliable data
         Acquisition of Data: Chief
   Explore thoroughly
   Patient should review all relevant symptoms
   Interview reveals the patient’s level of expression
    and personality
   Pitfalls in the interview process
    • Cultural influences, attitudes, fears, ignorance and
      memory loss altering the reliability of the historian
   Ask branching questions
    • Intention is to amplify and distill various diagnostic
      hypotheses or “hunches”
   Past medical, family and social history may reveal
   ROS provides information
      Acquisition of Data: Physical
   Concentrates on region of the chief complaint and
    any associated findings
   General survey physical examination is important
   Vital signs – one of the most cost-effective tests
    • Elevated temperature with back pain may indicate
   Abnormal findings must be independent of their
    specific anatomic location, and separate from the
    designation or diagnosis
   Physical examination answers the question, “How
    sick or abnormal is this patient?”
     Acquisition of Data: Abnormal
   Often will trigger additional physical
    • Ex. T/S scoliosis in a very tall person may
      prompt a cardiac evaluation to exclude
   Patient’s examination should be
    considered ongoing
   Subsequent visits should allow for a brief
    review of the positive findings and
    identification of new findings or
    Analysis and Ranking of Positive
   Pertinent findings are listed in the order of
    apparent relevance
   This is point where diagnostic accuracy is
    • Improper significance results in either too much, or too
      little, consideration for a given finding
   Time and natural course of a disease may alter
    the frequency and significance of a given finding
   Primary or key findings demonstrate high
    sensitivity or specificity
    • Ex. Weakness in all extremities or quadriparesis
      suggests a stenosis of the spinal cord. Constipation or
      vertigo are nonspecific
    Analysis and Ranking of Positive
      Findings: Common Errors
   Arise when insufficient data are available
    as a result of careless interview or
    examination techniques (or the physician’s
    knowledge is inadequate or lacks
    interpretive experience)
   Last case bias – influences clinical
    reasoning due to recent diagnosis
   Avoid the tendency to force congruence
    with a diagnostic classification
            System Assignment
   Positive findings should be assigned to one or
    more of the physiological systems
   Acute or chronic ambulatory pain syndromes
    arise in association with MSK and neurological
    • Radiculopathy, myelopathy, weakness, muscle atrophy
      and spinal segmental fixation
   GU system
    • M/C extraspinal source of referred pain to the lower T/S
      and L/S
   Other systems
    • Endocrine, cardiovascular, respiratory, GI and
        Differential Categories
   May be variable and arbitrary
   Categories include:
    • Neoplasm
    • Infection
    • Vascular
    • Trauma
    • Arthritide
    • Endocrine
    • Congenital
   Most life-threatening
   Malignant neoplasms of the primary or
    metastatic variety must be suspected in
    any adult patient presenting with
    progressive spinal or pelvic pain
   Average delay in the diagnosis of skeletal
    metastasis is 10 months
   Suspicious findings
    • Intractable skeletal pain or pain persisting day
      and night for a duration exceeding 5 days
    Neoplasm: Clues with Important
   Physical findings of weakness, unexplained fever,
    lymphadenopathy, organomegaly, or any
    progressive sensory or motor deficit
   Lab findings
    • Microcytic or macrocytic anemia, elevated sedimentation
      rate (ESR), hypercalcemia, elevated alkaline or acid
      phosphatase, proteinuria, and monoclonal gammopathy
      are associated with skeletal malignancy
   Negative lab tests and radiographs never exclude
    the possibility of skeletal malignancy
   Poor sensitivity of radiography limits its role in
    the early diagnosis of skeletal malignancy
   Can mimic disorders of almost any
   Cardinal clinical manifestations
    • Acute onset of fever, chills, adenopathy,
      malaise and myalgia
   Joint infections in the appendicular
    • Closed posttraumatic effusion that is warm
   Spinal infections (discitis)
    • Considered when spinal or pelvic surgery is
      antecedent to progressive spinal pain and
      febrile patient
    Infection: Constitutional Signs
   Anorexia
   Weight loss
   Malaise
   IV drug abusers and
    immunocompromised patients are
    prone to bone and joint infections
   Lab findings
    • Elevated WBC and ESR
   Often overlooked when acute pain evolves over hours or days
    following an abrupt onset
   Headaches – esp. occipital, which are sudden and severe in the
    presence of altered consciousness or neurological deficits, herald
    a TIA or stroke
   Thromboemboli in the pulmonary or coronary circulation give rise
    to progressive chest pain, tachypnea, tachycardia or SOB
     • Often seen in leg
   Aneurysms of the abdominal aorta can erode the vertebral body
    giving rise to pain
   Peripheral occlusive vascular disease
     • Considered when signs of claudication are noted
   Unilateral edema
     • In either extremity warrants consideration of vascular or lymphatic
   Bilateral lower extremity edema is a sign of congestive failure
   Frequent source of ambulatory pain syndromes
   Often arises from vehicular or work-place accidents or from sports
   Ligamentous injury in the C/S must be carefully sought
   Atlantoaxial instability can be excluded by flexion –extension x-
   Occult fractures in the neural arches of the mid and lower C/S
    should be considered if severe posttraumatic cervical spine pain
    persists beyond 7 to 10 days
   Stress fractures
     • Skeletal pain provoked by activity and relieved by rest
   Fractures
     • Accompanied by history of trauma and pain with the exception of
       neurogenic arthropathy (minimally painful, if at all)
   Pathological fractures
     • Usually suspected after radiological evaluation reveals features of bone
       destruction and/or soft-tissue masses
   Source of most patient diagnoses
    presenting with a pain syndrome
   Macrotrauma is often precipitating
    event of degenerative arthroses
   May be precipitated by aggregate
    microtrauma from inefficient postural
    controls or work-place stresses
   Hallmark of a degenerative arthritide
    • Reproducible joint-based pain
             Arthritides: Common
   Vertebral column
    • Disc degeneration and herniation,
      segmental instability and spinal stenosis
         Signs: altered joint mobility, radiculopathy,
          referred pain, reflex sympathetic dystrophy,
          atrophy, spasticity, weakness or claudication
   Myofascial trigger points are often
    located in neurofacilitated segments
      Arthritides: Inflammatory
   RA
   AS
   Characterized by a history of pain in
    multiple bilateral joints
    • Morning stiffness
    • Swelling
        Arthritides: Metabolic
   Gout
   Pseudo-gout
   Require laboratory diagnosis and
    joint aspiration for confirmation
   Also includes metabolic and nutritional
   One of the most challenging diagnostic
    categories to evaluate
    • Endocrine glands and metabolism govern
      physiological activities throughout the body
   Inspection often raises the question of an
    endocrine-metabolic disorder
   Usually arise due to excess or deficiency
    of hormone secretion
   Target receptor responsiveness may be
    absent or elevated
               Endocrine: Common
   Manifestations
    • Weakness, easy fatigability, growth abnormalities,
      hirsutism, weight loss or obesity and altered
      reproductive function (impotence, irregular menstrual
   Disorders
    • Osteoporosis (m/c cause of spinal pain of metabolic
    • Diabetes mellitus
    • Hyper- and hypothyroidism
    • Hypoglycemia
   Definitive diagnosis
    • Lab tests
          Specific hormone levels
    • Advanced imaging
   Also grouped with dysplasias and genetic
   Short stature of dwarfism
   Spider-like hands and feet of Marfan’s
   History of recurrent fractures in OI
   Most significant congenital spinal anomaly
    is an unstable os odontoidium
    • Diagnosed by flexion/extension radiographs
            Differential Diagnosis
   Constructed in order of declining probability
   Influenced by
    • Age, gender, race, disease prevalence, clinical features
   Common sense, logic and intuition will eliminate the
    diagnostic possibilities and advace the probabilities
   Be specific (ex. Spinal stenosis, myofascitis of gluteus
   Lack of adequate findings results in a nonspecific diagnosis
    (this is o.k. since testing strategies will help to narrow
   Process involves significant negative or absent findings and
    the presence of positive findings
   Try to include treatable conditions
                Testing Strategy
   Proceed with treatment versus employ testing
   Determined by
    • Level of certainty or confidence
    • Presence of conditions capable of inflicting significant
      morbidity or mortality
    • Cost effectiveness of further testing
   If differential contains morbid or potentially fatal
    condition, you must rule out or confirm their
   Sensitive tests are able to detect a given disorder
   Specific tests confirm its presence
Testing Strategy: Appropriate Test
   Necessary for diagnostic orientation, patient
    safety and cost effectiveness
   Avoid “shot gun”, routine or battery testing
   All tests flow from the differential diagnosis
    • Diff dx arises from the positive findings yielded by H and
      P examination
   Many patients will have the results of treatment
    modify the diff dx
    • Treatment response is of diagnostic value
   Results of the approriate testing strategy should
    be a working diagnosis that is consistent with all
    clinical information
   Use of appropriate therapeutic measures
    directed at one or more diagnoses
   Natural course of a disorder is known and
    should be altered by appropriate
   Failure to alter the course implies
    • Treatment is inadequate
    • Other modes of treatment should be employed
    • The diagnosis needs revision (must be
      performed in a timely manner) – failure to
      arrive at a new diagnosis requires specialty
    Treatment: Clinical Hypesthesia
   Refers to the failure to discriminate
    b/t a benign etiology of pain and a
    newly superimposed life-threatening
    source of pain
   Physician is lulled into an expectation
    of incurable chronic pain
   Periodic exams can prevent this
Treatment: Collection and Analysis
      of Clinical Information
   A dynamic process
    • Begins with the patient’s introduction
    • Ongoing with constant revision
         Depends on new information from the
          interview, physical examination, test results,
          treatment response
   Effective clinical decisions result from an
    orderly and strategic reasoning method
   Provides cost effective clinical
   Emergence of one or two diagnoses from
    a dozen or more differential considerations
    can be as satisfying a feature of patient
    care as a favorable response to treatment
Differential Diagnosis Strategy

  Data Acquisiton       Analysis of Positive Findings   Systems Assignment

   Treatment                                            Differential Category

    Diagnosis               Testing Strategy            Differential Diagnosis

                    Differential Diagnosis Strategy
   Kettner, N.W. D.C. Tracts, June
    1989, Vol. 1, No. 3

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