Differential Diagnosis

1
Differential Diagnosis

• Theodore M. Godlaski
• College of Social Work
• University of Kentucky

2
The Diagnostic Problem

• DSM Diagnosis a somewhat paradigmatic symptoms
  cluster at the syndromal level of abstraction
• However, individuals usually present clinicians
  with a single symptom/small set of symptoms
• That they find most distressing
• That they are most comfortable discussing
• Getting from a single or small number of related
  symptom to a diagnosis useful for treatment is
  what differential diagnosis is all about.

3
Step 1

• Is the presenting symptom for real?
• This does not imply that one should always
  mistrust what the patient says.
• However there are diagnoses in which conscious
  feigning of symptoms is usual (Malingering and
  Fictitious Disorder) and one in which unconscious
  feigning of symptoms is usual (Conversion
  Disorder).

4
Step 1 (corollaries)

• Is this a situation in which feigning of symptoms
  is more typical ER, forensic evaluation, prison,
  inpatient unit?
• Does the presentation of symptoms conform more to
  a popular view of a disorder than to an actual
  clinical entity?
• Do the symptoms shift significantly from one
  clinical encounter to the next?
• Do the symptoms mimic the presentation of a role
  model like a parent or another patient?
• Is the patient unusually manipulative or
  suggestible?

5
Step 2

• Rule out substance etiology (drugs of abuse,
  medications, toxin exposure).
• Does the individual use any substances?
• This includes dependence, abuse, recreational
  use, medical use, and environmental exposure.
• This will involve a thorough history and
  evaluation, laboratory tests, and toxicology.
• In an aging population with less cautious use of
  parmacotherapy, medication use is an increasing
  concern.

6
Step 2

• What is the etiologic relationship between
  substance use and psychiatric symptoms?
• The symptoms are a direct result of the effects
  of the substance use.
• The substance use is secondary to the psychiatric
  symptoms.
• The psychiatric symptoms and substance use are
  independent of each other.

7
Step 2

• Temporal sequence is a helpful, but not
  infallible, guide.
• If the onset of psychiatric symptoms clearly
  precedes the onset of substance use, it is
  probably a primary psychiatric disorder.
• If the onset of substance use clearly precedes
  the psychiatric symptoms than the symptoms are
  more likely to be substance induced.
• If the psychiatric symptoms abate in about 4
  weeks after substance intoxication or withdrawal,
  the symptoms are more clearly substance induced.
• Excepting Substance Induced Persisting Dementia
  or Amnesiac Disorder.

8
Step 2

• Caveats
• Often individuals suffering from substance use
  and psychiatric symptoms are not the best
  historians of their own experience.
• Substance misuse and psychiatric disorders often
  have their onset in late adolescence without any
  causative link.
• If psychiatric symptoms are severe and pose a
  risk to self or others, waiting 4 weeks to
  determine etiology raises serious questions.

9
Step 2

• Is the pattern of substance use or withdrawal
  sufficient to account for the symptoms?
• Is the nature, amount, and duration of substance
  use consistent with the observed symptoms?
• Not all substances nor all dose levels of
  specific substances produce specific symptoms.
• Is the pattern of substance use consistent with
  an attempt to relieve the symptoms?
• Are there other factors like heavy genetic
  loading for a specific psychiatric problem that
  point to a non-substance induced etiology?
• In the absence of persuasive evidence in either
  direction, could the two disorders simply be
  co-morbid?

back
10
Step 3

• Rule out a disorder due to a general medical
  condition?
• The clinical implication of this step are
  profound.
• Differential diagnosis is complicated
• Symptoms of some psychiatric conditions and many
  general medical conditions can be identical.
• Sometimes the first presenting symptom of a
  general medical condition is psychiatric.
• The relationship between medical conditions and
  psychiatric conditions can be complicated
• Patients are often seen in mental health setting
  where there is low expectation of and little
  familiarity with general medical conditions.

11
Step 3

• Just as with substance use, virtually any
  psychiatric presentation can be caused by the
  direct physiologic effects of a general medical
  condition (e.g. Mood Disorder due to
  Hypothyroidism).
• A good diagnostic evaluation should contain a
  thorough history and physical as well as tests
  for those medical conditions most likely to cause
  the presenting symptoms ( thyroid function tests
  for depression, brain imaging for late-onset
  psychosis)
• In social work practice, involvement of a
  physician with good diagnostic skills, like and
  Internist, in the evaluation process is very
  important.

12
Step 3

• If a general medical condition is present, its
  etiologic relationship, if any, to the
  psychiatric symptoms must be established.
• The medical condition causes the psychiatric
  symptom by direct action on the CNS.
• The general medical condition causes the
  psychiatric symptoms through a indirect or
  psychological mechanism.
• Medication taken for the medical condition causes
  the psychiatric symptoms.
• The psychiatric symptoms adversely effect the
  medical condition.
• The psychiatric symptoms and the medical
  condition are purely coincidental,

13
Step 3

• There are some clues that are helpful, but not
  infallible, in making the clinical judgment
  mentioned earlier.
• Temporality do psychiatric symptoms follow the
  onset of the medical condition, vary in intensity
  with it, and disappear when it is resolved?
• Remember that psychiatric symptoms can precede,
  by some time, the onset of some medical problems
  or not occur until late stages of others.

14
Step 3

• Atypicality are the psychiatric symptoms
  atypical in pattern, age of onset, or course.
• e.g. significant weight loss and severe fatigue
  with mildly depressed mood, first onset of Manic
  Episode in an elderly individual, severe
  disorientation accompanying psychotic symptoms.
• Remember, manifestation of psychiatric disorders
  is very heterogeneous and atypical presentations
  are not unknown.
• If you determine that a medical condition is
  causing the psychiatric symptoms, determine which
  DSM-IV-TR diagnosis of Mental Disorders Due to a
  General Medical Condition best describes the
  presentation.
• A decision tree or algorithm is very helpful.

15
Step 4

• Determine the specific primary disorder(s).
• The arrangement of disorders in the DSM-IV-TR
  into broad categories of disorders is done to
  somewhat facilitate this process
• Disorders First Diagnosed in Infancy, Childhood,
  or Adolescence Delirium, Dementia, Amnestic, and
  other Cognitive Disorders Substance-Related
  Disorders Schizophrenia and other Psychotic
  Disorders Mood Disorders Anxiety Disorders
  Somatoform Disorders Factitious Disorders
  Dissociative Disorders Sexual and Gender
  Identity Disorders Eating Disorders Sleep
  Disorders Impulse-Control Disorders Adjustment
  disorders Personality Disorders

16
Step 4

• The problem is that many disorders share common
  symptoms

Irritability Acute Stress Disorder ASPD Attention
al Deficit/Hyperactivity Disorder BPD Conduct
Disorder Cyclothymic Disorder Delusional
Disorder Dysthymic Disorder GAD Hypomanic
Episode Major Depressive Disorder Manic
Episode Mixed Episode PTSD Schizoaffective
Disorder Schizophreniform Disorder Schizophrenia S
ubstance Use/Withdrawal
Weight Loss Anorexia Nervosa Dysthymic
Disorder Hypomanic Episode Major Depressive
Disorder Manic Episode Mixed Episode Substance
Intoxication
Insomnia Acute Stress Disorder Cyclothymic
Disorder Delirium Dysthymic Disorder GAD Hypomanic
Episode Major Depressive Disorder Manic
Episode Mixed Episode Nightmare
Disorder PTSD Schizoaffective Disorder Schizophren
iform Disorder Schizophrenia Substance
Use/Withdrawal
17
Step 4

• The problem is that many disorders share common
  symptoms

Irritability Acute Stress Disorder ASPD Attention
al Deficit/Hyperactivity Disorder BPD Conduct
Disorder Cyclothymic Disorder Delusional
Disorder Dysthymic Disorder GAD Hypomanic
Episode Major Depressive Disorder Manic
Episode Mixed Episode PTSD Schizoaffective
Disorder Schizophreniform Disorder Schizophrenia S
ubstance Use/Withdrawal
Weight Loss Anorexia Nervosa Dysthymic
Disorder Hypomanic Episode Major Depressive
Disorder Manic Episode Mixed Episode Substance
Intoxication
Insomnia Acute Stress Disorder Cyclothymic
Disorder Delirium Dysthymic Disorder GAD Hypomanic
Episode Major Depressive Disorder Manic
Episode Mixed Episode Nightmare
Disorder PTSD Schizoaffective Disorder Schizophren
iform Disorder Schizophrenia Substance
Use/Withdrawal
18
Step 4

• The problem is that many disorders share common
  symptoms

Irritability Acute Stress Disorder ASPD Attention
al Deficit/Hyperactivity Disorder BPD Conduct
Disorder Cyclothymic Disorder Delusional
Disorder Dysthymic Disorder GAD Hypomanic
Episode Major Depressive Disorder Manic
Episode Mixed Episode PTSD Schizoaffective
Disorder Schizophreniform Disorder Schizophrenia S
ubstance Use/Withdrawal
Weight Loss Anorexia Nervosa Dysthymic
Disorder Hypomanic Episode Major Depressive
Disorder Manic Episode Mixed Episode Substance
Intoxication
Insomnia Acute Stress Disorder Cyclothymic
Disorder Delirium Dysthymic Disorder GAD Hypomanic
Episode Major Depressive Disorder Manic
Episode Mixed Episode Nightmare
Disorder PTSD Schizoaffective Disorder Schizophren
iform Disorder Schizophrenia Substance
Use/Withdrawal
19
Step 4
20
Step 5

• If the symptom pattern or the severity of
  impairment or distress does not meet criteria for
  a specific diagnosis, differentiate adjustment
  disorder from not otherwise specified.
• If the clinical judgment is made that the
  symptoms developed from a maladaptive response to
  a psychosocial stressor, then adjustment disorder
  appropriate.
• If the judgment is that the stressor is not
  responsible for the development of the symptoms,
  than the relevant Not Otherwise Specified
  category can be diagnosed.
• Given the ubiquity of stressors, the point is not
  whether a stressor is present or not but whether
  it is the etiology of the symptoms.

21
Step 6

• Establish the boundary with no mental disorder
• This is an obvious but not always an easy step to
  take.
• Many symptoms are so ubiquitous that they occur
  at least briefly in the lives of most people.
• At some time most individuals will experience
  symptoms of anxiety, depression, difficulty
  sleeping, or sexual dysfunction.
• It is important not to pathologize what is really
  the human condition.
• The disturbance must cause clinically
  significant impairment or distress in social,
  occupational, or other important areas of
  functioning.

22
Step 6

• The diagnosis of Hypoactive Sexual Desire
  Disorder should not be made in someone with low
  sexual desire, who is not in a current intimate
  relationship with anyone, and who is not
  particularly bothered by it.
• The problem is that what is clinically
  significant is greatly influenced by cultural
  context, the setting in which the individual is
  seen, clinician bias, client bias, and
  availability of resources.
• Unfortunately there is little solid research and
  no hard and fast rules that can guide this
  decision.

23
Comorbidity

• Although it is best to follow the principle of
  parsimony, it is also important to remember that
  most diagnoses are not mutually exclusive.
• In an individual with delusions, hallucinations,
  and mood symptoms a decision must be made among
  Schizophrenia, Schizoaffective Disorder, and Mood
  Disorder with Psychotic Features.
• In an individual with multiple unexpected panic
  attacks, significant depression, and a
  maladaptive perfectionistic and rigid personality
  style the diagnoses of Major Depressive Disorder,
  Panic Disorder, and Obsessive-Compulsive
  Personality Disorder may all apply.

24
Comorbidity

• Using multiple diagnoses is neither good nor bad
  so long as the implications are understood.
• Do not hold the mistaken view that multiple
  descriptive diagnoses are actually independent
• A may cause or predispose to B (ASPD, SUD)
• B may cause or predispose to A (OCD, Eating
  Disorders)
• An underlying condition C may predispose to both
  A and B (PTSD, Agoraphobia, SUD)
• A and B may be part of a larger syndrome
  artificially split in the diagnostic system
  (PTSD, BPD)
• The comorbidity is a chance co-occurrence in
  conditions with high base rates (MDD and SUD)

25
Comorbidity

• Having more than one DSM-IV-TR diagnosis does not
  mean that there is more than one underlying
  pathophysiological process.
• The diagnoses are not entities but descriptive
  building blocks, useful for communicating
  diagnostic information and guiding therapeutic
  choices.

26
Practice

• Consider the case of a 38 year old married male
  who is referred for evaluation after a second
  DUI. He readily admits that he is a regular and
  heavy drinker, that he has tried to stop drinking
  several times but without any sustained success,
  and that he often drinks more than he intends. He
  also complains of feelings of intense sadness,
  difficulty sleeping, weight loss, constant sense
  of fatigue, feelings of guilt and worthlessness,
  and occasional thoughts of suicide.

27
Practice

• This is not an atypical presentation and poses a
  serious differential challenge.
• Although this is a kind of forensic evaluation,
  let us assume that there is no reason to believe
  that the individual is not being perfectly honest
  about his symptoms.
• Let us further assume that a recent history and
  physical reveals no apparent medical problem
  which might explain the symptoms.

28
Practice

• The diagnostic question then is Is this an
  individual whose Major Depressive Disorder is
  secondary to his Alcohol Dependence, or whose
  Alcohol Dependence is secondary to his Major
  Depressive Disorder, or who has both Major
  Depressive Disorder and Alcohol Dependence as
  comorbid conditions.
• Diagnostic tree

29
Practice

• Consider the case of a 28 year old, unmarried
  woman, who seeks help because of panic attacks.
  She was perfectly fine until she was in her last
  year of graduate studies in molecular biology and
  was attacked and carjacked in the library parking
  lot late one night. Her attacker forced her to
  dive, at knife point, to a deserted area where he
  raped, beat, and left her. She was so shaken by
  the experience that she dropped out of school
  without finishing her degree. She still has
  nightmares about the attack and takes
  benzodiazepines, off and on, to help her sleep.
  She eventually got a job as a technician in a
  medical lab and was doing better until the lab
  started running a late shift. When she works
  late, the thought of having to go to her car in a
  dark and deserted parking lot makes her feel like
  she is smothering. When she can convince someone
  to go with her to her car, she feels better. But
  several times she could not find anyone and her
  heart beat so fast and hard she was convinced she
  was about to die. She doesnt want to loose her
  job but she also doesnt want to continue to live
  as she has for the past several months.

30
Practice

• The presenting symptom is panic attacks. The
  Diagnostic question is whether this symptom is
  the result of the after effects of benzodiazepine
  use, a developing anxiety disorder, or trauma.
• Diagnostic tree

31
Practice

• Consider the case of a 57 year old, widowed,
  female who is brought to the emergency room by
  EMTs. She was wandering around her neighborhood
  in a flowered house dress and slippers early on a
  chilly November morning. The neighbors saw her
  and attempted to talk to her but when she didnt
  seem to make a lot of sense, they called 911. The
  paramedic says that in talking to the neighbors
  he discovered that she has lived in her house for
  at least 20 years. Five years ago her husband
  died and since then they have seen little of her.
  They said that she has no visitors except the
  local grocery that delivers and the local liquor
  store which also delivers. The paramedic says
  that when asked if she knew were she was she
  responded, Yes, in San Francisco on my
  honeymoon, but I seem to have gotten lost and
  cant remember how to get back to the hotel. Ill
  be fine as soon as I can find my husband.
• She is very thin and looks considerably older
  than her age. Her skin has a somewhat sallow and
  yellowish pallor that seems to be more pronounced
  in her neck and upper chest. There is a very
  faint smell of wine about her but she does not
  appear to be intoxicated. Her BP is in normal
  range for her gender and age but here temperature
  is slightly elevated (99.8 F). When questioned
  about what has happened she is either non
  responsive or talks about recently being married
  and about the plans she and her husband have once
  they return to Lexington. She appears to be more
  confused than frightened. When asked were she
  thinks she is now, she responds, In the
  Visitors Aid Center where well get everything
  sorted out shortly.

32
Practice

• Contact with the local grocery reveals that she
  generally orders the same things every week
  bread, eggs, meat, assorted vegetables, milk,
  orange juice, occasionally oil or flower, and
  always a large bottle (100 tabs) of extra
  strength acetaminophen. Contact with the liquor
  store reveals that she always orders 3 bottles of
  white wine, usually pinot grigio.
• This case presents very considerable diagnostic
  challenges, some of which may be beyond your
  current expertise. It is included for the
  following reasons
• Because there will be cases beyond your expertise
  no matter how much you know
• It illustrates the need to be tentative in
  diagnosis, especially when there is much that is
  unclear
• It is a case in which treatment based on the
  wrong diagnosis can be fatal.
• Diagnostic Tree