Differential Diagnosis

1. Differential Diagnosis Presented by M.A. Kaeser, DC Winter 2010

2. Introduction • Patients seek physician services for 2 reasons • 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

3. 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

4. Acquisition of Data • History and physical exam are the most essential components of the diff dx process • Achieved by intuition and sensory input • Verbal and nonverbal clues help formulate the tentative diagnostic impressions • Nonverbal example: oversized clothing from weight loss • All diagnostic decisions are dependent upon reliable data

5. Acquisition of Data: Chief Complaint • 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 clues • ROS provides information

6. Acquisition of Data: Physical Examination • 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 pyelonephritis • 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?”

7. Acquisition of Data: Abnormal Finding • Often will trigger additional physical assessments • Ex. T/S scoliosis in a very tall person may prompt a cardiac evaluation to exclude Marfan’s • 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 complications

8. Analysis and Ranking of Positive Findings • Pertinent findings are listed in the order of apparent relevance • This is point where diagnostic accuracy is compromised • 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

9. 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

10. 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 systems • 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 dermatological

11. Differential Categories • May be variable and arbitrary • Categories include: • Neoplasm • Infection • Vascular • Trauma • Arthritide • Endocrine • Congenital

12. Neoplasm • 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

13. Neoplasm: Clues with Important Value • 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

14. Infection • Can mimic disorders of almost any etiology • Cardinal clinical manifestations • Acute onset of fever, chills, adenopathy, malaise and myalgia • Joint infections in the appendicular skeleton • Closed posttraumatic effusion that is warm • Spinal infections (discitis) • Considered when spinal or pelvic surgery is antecedent to progressive spinal pain and febrile patient

15. 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

16. Vascular • 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 compression • Bilateral lower extremity edema is a sign of congestive failure

17. Trauma • Frequent source of ambulatory pain syndromes • Often arises from vehicular or work-place accidents or from sports endeavors • Ligamentous injury in the C/S must be carefully sought • Atlantoaxial instability can be excluded by flexion –extension x-rays • 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 neurogenicarthropathy (minimally painful, if at all) • Pathological fractures • Usually suspected after radiological evaluation reveals features of bone destruction and/or soft-tissue masses

18. Arthritide • 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

19. Arthritides: Common Complications • 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

20. Arthritides: Inflammatory • RA • AS • Characterized by a history of pain in multiple bilateral joints • Morning stiffness • Swelling

21. Arthritides: Metabolic • Gout • Pseudo-gout • Require laboratory diagnosis and joint aspiration for confirmation

22. Endocrine • Also includes metabolic and nutritional disorders • 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

23. Endocrine: Common Endocrinopathies • Manifestations • Weakness, easy fatigability, growth abnormalities, hirsutism, weight loss or obesity and altered reproductive function (impotence, irregular menstrual cycles) • Disorders • Osteoporosis (m/c cause of spinal pain of metabolic origin) • Diabetes mellitus • Hyper- and hypothyroidism • Hypoglycemia • Definitive diagnosis • Lab tests • Specific hormone levels • Advanced imaging

24. Congenital • Also grouped with dysplasias and genetic disorders • 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

25. 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 maximus) • Lack of adequate findings results in a nonspecific diagnosis (this is o.k. since testing strategies will help to narrow diagnosis) • Process involves significant negative or absent findings and the presence of positive findings • Try to include treatable conditions

26. Testing Strategy • Proceed with treatment versus employ testing procedures • 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 presence • Sensitive tests are able to detect a given disorder • Specific tests confirm its presence

27. Testing Strategy: Appropriate Test Selection • 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

28. Treatment • Use of appropriate therapeutic measures directed at one or more diagnoses • Natural course of a disorder is known and should be altered by appropriate treatment • 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 consultation

29. 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 mistake

30. 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

31. Conclusions • Effective clinical decisions result from an orderly and strategic reasoning method • Provides cost effective clinical management • 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

32. Differential Diagnosis Strategy Data Acquisiton Analysis of Positive Findings Systems Assignment Treatment Differential Category Differential Diagnosis Diagnosis Testing Strategy Differential Diagnosis Strategy

33. References • Kettner, N.W. D.C. Tracts, June 1989, Vol. 1, No. 3