15
3
The Vignette
ADULTVIGNETTES 15
HOW TOAPPROACH AVIGNETTE 15 ADULTVIGNETTETOPICS(VARIES) 16 THELASTTENMINUTES 17
THECANDIDATEWITHOUT ACLUE 18 THEPEDIATRICVIGNETTE 19
AGECATEGORIES 19
What is a vignette?
A vignette is a description of a neurological clinical case open for discussion. In the Neurology Board there are two types of vignettes, the adult vignette and the pe- diatric vignette. For the adult neurologist the live patient and the adult neurology case vignettes constitute the ma- jor portion of the exam, while the pediatric neurology case vignettes make up the minor part of the exam. The child neurologist candidate will be assigned a live pedi- atric patient (major), pediatric case vignettes (major) and adult neurology case vignettes (minor).
All major parts of the exam have to be a pass for a final grade of pass to be assigned for that part.
Adult and pediatric vignettes are contained in booklets.
Each booklet is different and contains different vignettes.
Adult Vignettes
The adult vignette is a description of a clinical case con- cerning adult neurology open for discussion. It contains a neurological subject and it is the description of a neu- rological case. A vignette can vary in length and difficulty and can also contain elements that are not pertinent to the diagnosis as they can have one or more obvious correct answers or more than one pertinent answer. In a one-hour time frame, 50 minutes are dedicated to multiple adult vignettes and the last 10 minutes of the session are re- served for one or more questions and vignettes created by the examiners, usually concerning neurological emer- gencies.
After the candidate introduces himself or herself, he or she is given a booklet and is told to go to a certain case number.
The examiner then gives the candidate the choice of reading the case aloud or in silence, or having the case read aloud by the examiner.
The decision at this point may be an important one, as
some people find themselves in trouble when they find out they made the wrong choice. My suggestion is to select the modality you are most comfortable with. Some people find reading to themselves more conducive to comprehension and concentration, while for others it does not appear to make a difference whether they read the vignettes or it is read to them.
Although some candidates have talked about a “feel- ing” that the examiners would prefer the case to be read, there is no clear evidence that this may be the case. Note taking is allowed, but in the interest of time and practi- cality one should avoid writing copious notes. Also, if after a first reading you have some doubts or, as it some- times can happen, you have no clue, you can always re- quest to read the vignette a second time.
How to Approach a Vignette
The approach to a vignette is
• Read.
• Think while you are reading, highlighting the most relevant signs and symptoms, which will be the basis for a differential diagnosis.
• Localize.
After the candidate reads the vignette the candidate is expected to briefly summarize the case, highlighting the most relevant signs and symptoms, which will be the ba- sis for a differential diagnosis. The rule of thumb in doing this is not to jump to a definite diagnosis without building an argument, as this gives the examiners an idea of lack of in-depth understanding of neurological complexities.
The three main guiding principles that may help you organize your presentation are
• Localization.
• Categorization.
• Differentiation.
16 3. The Vignette
Localization
Localization is an essential step in generating a differ- ential diagnosis. Recognizing the site of a lesion is the first step toward ruling in some illnesses and ruling out others. When localization is self-evident, it is advisable to state it anyway as a reminder to the examiners that the obvious was not overlooked. First comes a broader lo- calization division that places the lesion in the
• Central nervous system.
• Peripheral nervous system.
• Both.
Next comes a narrower localization process. For ex- ample, in the central nervous system the level could be
• Supratentorial.
• Basal ganglia.
• Brainstem: Intrinsic and extrinsic.
• Cerebellum.
• Spinal cord.
• Motor unit:
Anterior horn cells.
Peripheral nerve.
Neuromuscular junction.
Muscle.
Categorization
The main categories of neurological disorders are
• Vascular.
• Neoplastic.
• Infectious/inflammatory.
• Toxic/metabolic.
• Degenerative.
The lesion can also be divided into:
• Focal.
• Multifocal (spatial and/or temporal).
Finally, the candidate should try to discuss the possible etiology of the case.
Differentiation
What the examiners are looking for is a well-organized and thought-out presentation on differential diagnosis on the case.
A few tips on organizing and presenting data may help 1. Do not rush to an obvious diagnosis; it gives the ex- aminer an impression of lack of depth and critical analysis in your clinical judgment and it exposes you to unnecessary risks of further questioning by the examiners.
2. Be comprehensive in your including diagnosis but also pertinent to the case. In other words, it does not give a good impression to mention a potential diagnosis for
which there is no clear-cut support in the symptoms/
signs or history.
3. Characterize the probability of your diagnostic clas- sification in a way that is hierarchically clear. For ex- ample, you might want to say “I am considering . . . in the differential diagnosis because of.. . . However, because of,. . . this diagnosis would be less likely.
4. Provide all the supporting information (symptoms/
findings/history/laboratory data) to support your likely diagnosis.
5. When the picture of a probable diagnosis is not clear because of lack of data, mention what is missing, so as to prove that you know what it would take to get there.
6. Provide more details and supporting evidence for your most likely diagnosis.
7. Be prepared to be interrupted with questions. This should in no way be interpreted as negative, and you should be able to resume your discourse where you left off.
Adult Vignette Topics (Varies)
The topics of the adult vignette are those concerning the major categories of neurological disorders. Some very common topics are presented below.
First we will consider the disturbances of cerebrospinal fluid (CSF), normal pressure hydrocephalus (NPH), and pseudotumor cerebri. NPH is characterized by slow pro- gressive gait disorder, impairment of mental functioning, and sphincteric incontinence.
Bening or idiopathic intracranial hypertension (pseu- dotumor cerebri) is a very popular topic. Diagnosis is made by the clinical presentation of headache and pap- illedema, elevated CSF pressure (⬎250 mm Hg) and nor- mal cerebral imaging. Brain tumor and cerebral venous thrombosis in particular must be ruled out.
Cerebrovascular disorders, ischemic and hemorrhagic, thrombotic and embolic, are frequently found; par- ticularly
• Amaurosis fugax (carotid).
• Vertebrobasilar insufficiency.
• Lacunar and large-vessel infarcts.
Middle cerebral artery and basilar artery occlusion, in- cluding the special top of the basilar artery are also fre- quently found.
Within the hemorrhagic disorders, basal ganglia and cerebellar hematoma are essential to recognize.
And last, subarachnoid hemorrhagic and sinus throm- bosis need to be considered.
Intracranial neoplasms are the third category. They can be presented in cases of new-onset seizures or signs of increased intracranial pressure. Neoplasms as part of pop- ular vignettes include:
• Acoustic neuroma.
• Pituitary adenoma.
• Tumors of the foramen magnum, etc.
Other popular topics in this category are
• Meningeal carcinomatosis.
• Paraneoplastic syndromes, particularly cerebellar de- generation and Lambert-Eaton myasthenic syndrome (LEMS).
The next category of disorders are the infections. Com- mon topics include
• Viral infections, particularly Herpes encephalitis.
Creutzfeldt-Jacob disease.
HIV/HTLV myelopathy.
• Bacterial infections Tubercular meningitis.
Lyme disease.
• Parasitic infections, particularly Neurocysticercosis
Within the category of traumatic disorders, it is im- portant to keep in mind
• Chronic subdural hematoma.
• Carotid cavernous fistula.
Next comes the toxic/metabolic category, including:
• Complications of alcohol abuse, particularly Wernicke- Korsakoff syndrome and vitamin deficiencies, particu- larly B12.
• Neuroleptic malignant syndrome, often recurring.
Another category is demyelinating disorders and multiple sclerosis with its various presentations (optic neuritis, transverse myelitis etc.).
Devic’s disease should also be considered.
In the category of degenerative disorders, very popular topics are
• Parkinson’s disease and parkinsonism, including pro- gressive supranuclear palsy (PSP).
• Dementia, including Pick’s disease and normal pres- sure hydrocephalus.
• Huntington’s disease and other choreas.
• Ballism.
• Peripheral nerve disorders with different components are a very important source of vignettes. The topics vary from very simple entrapment neuropathy (medial, radial, peroneal) to brachial and lumbar plexopathies.
Within the peripheral nerve disorders, acute and chronic inflammatory demyelinating polyradiculoneu- ropathy (AIDP and CIDP) are essential parts of very popular vignettes.
Neuromuscular function disorders include
• Myasthenia gravis.
• Lambert-Eaton myasthenic syndrome.
• Botulism.
Muscle disorders, particularly polymiositis, dermato- myositis, and, less likely inclusion body myositis are fre- quently included.
Motor neuron disease, particularly amyotrophic lateral sclerosis (ALS), is a very important topic and very pop- ular in the Neurology Board Examinatiom.
Next to be considered are the headeache disorders, particularly migraine and clusters headaches, and seizure disorders, particularly temporal lobe and the partial com- plex seizures and then new-onset seizure secondary to neoplasm.
The Last Ten Minutes
The last 10 minutes of the hour are devoted to clinical cases generated by the examiners. These most likely con- cern neurological emergencies. Every well-trained neu- rologist should be able to recognize and treat emergency situations. Obviously, the inability to recognize an emer- gency, even if you had a previous good performance with the other vignettes, will cause you to fail this part.
Some of the most common emergencies that you need to recognize include
• Cerebellar hemorrage. This is a very important topic and a very popular, recurrent, clinical case presented in the oral Board.
• Myasthenic crisis.
• Neuromuscular disorder causing acute respiratory fail- ure (other than myasthenic crisis).
• Convulsive status epilepticus.
• Acute spinal cord compression.
• Increased intracranial pressure.
Summary of the Most Important Findings in Some Neurological Emergencies
Cerebellar Hemorrhage (see also vignette in cerebrovascular disorders)
Establishing the diagnosis is important because of the po- tentially serious outcome if not treated and the contrasting surgical treatment. Important clues for the classical pre- sentation include a patient brought to the ER
• Unable to stand or sit.
• Complaining of headache.
• Vertigo and vomiting also present.
• Signs of brainstem compression.
Treatment consists of urgent evacuation through a sub- occipital craniectomy. Relief of brainstem compression may be life saving and operative morbidity is low.
18 3. The Vignette
Myasthenic Crisis
Typical patients known to have myasthenia develop signif- icant respiratory insufficiency and oropharyingeal muscle weakness requiring mechanical ventilation. Therefore,
• Myasthenic patients with acute shortness of breath and dysphagia are in myasthenic crisis.
Precipitating factors include
• Infections.
• Surgery.
• Medications changes: Initiation or withdrawl of corti- costeroids.
• Antibiotics Neomycin.
Kanamycin.
Gentamycin.
Tetracycline.
Colistins.
Lincomycin.
Polymyxin.
• Antirheumatic agents.
D-penicillamine.
Cloropine.
• Cardiac drugs.
Procainamide.
Verapamil.
• Menstrual cycle or pregnancy (especially first tri- mester).
• Alcohol.
• Emotional stress.
You are expected to know how to manage a myasthenic crisis:
• Assessment of a respiratory function.
Forced vital capacity.
Negative respiratory force.
• Intubate if VC⬍ 12–15 ml/kg.
• Remove precipitating factors.
• Plasmapheresis is the best treatment for acute patients (Five exchange treatments of 3–4 liters each over a 1- week period is a typical program).
• If the patient has poor vascular access and there is con- cern about instituting plasmapheresis with cardiovas- cular instability, then IVG may be considered.
• Ventilated patients who have not previously been on steroids can be started on high doses of prednisone (60 mg daily).
Cholinergic Crisis
Cholinergic crisis occurs when an excessive amount of acetylcholine is present at the neuromuscular junction, desensitizing the acetylcholine receptors, leading to in- creasing weakness. These are patients with increased weakness after receiving cholinergic medications.
It can be suspected when the myasthenic patient pre- sents with
• Diarrhea.
• Abdominal cramps.
• Nausea, vomiting, excessive secretions.
• Diaphoresis.
• Fasciculations.
• Weakness.
• Worsening of the weakness with edrophonium.
Treatment is based on withdrawal of anticholinesterase drugs, ventilatory support, plasmapheresis.
Convulsive Status Epilepticus See vignette in Chapter 12.
The Candidate Without a Clue
The time may come when the examiners ask you a ques- tion that you are absolutely certain you cannot answer.
This is an extremely unpleasant situation to be in, and a variety of thoughts may crowd your mind. You may feel like you have no option whatsoever. Yet you do, and be- ing prepared for this circumstance may make the differ- ence. Here are some hints:
• Ask for a little time to think about it. Your examiners will understand.
• Quickly make an assessment in your mind about whether this is a make-it or break-it issue. In other words, is this question related to a must in your knowl- edge. This is important, because if, for example, you have already answered all the questions about treat- ment of generalized seizures and you are asked about a latest development, you may feel more confident re- sponding that you do not know.
• Even if you assess the essential nature of the topic, you may be better off conceding you do not know when the following circumstances occur:
1. Trying to guess may make things worse. Examiners do not like candidates “winging it.” These are sea- soned clinicians who can see through deceitful at- tempts and will not forgive you for it.
2. Trying to give an ambiguous or tentative answer may take you down a road you are unfamiliar with, a dangerous way of setting yourself up for further questions you may be unable to answer.
Overall, the strategy should be to minimize the losses in an honest way without giving the appearance of trying to manipulate the process.
In general, the candidate without a clue is usually the unprepared candidate who did not spend enough time in planning and pursuing a good preparation. However, there are exceptions. For example, in pediatric neurology, while reading a vignette, the candidate may feel so un-
familiar with the topic that the candidate may be unable to give an answer or discuss any differential diagnosis.
As indicated in the pediatric vignette part, it is accept- able to read the vignette one more time and highlight in your mind the symptoms that may help you formulate a list of possible categories of disorders. Once you identify the category, you can at least provide a list of possible differential diagnoses. For example, when dealing with developmental delay or regression with multisystem in- volvement, high on your list of categories should be a neurometabolic disorder. Some combinations may also offer you clues. Examples include
SeizureⳭ dementia ⳱ gray matter disorders.
Optic atrophy Ⳮ long tract signs ⳱ white matter disorders.
Mental regression, neurological findings, orange skin or mucosa⳱ think of adrenoleukodistrophy.
SeizuresⳭ pale patches on the skin Ⳮ mental retardation
⳱ tuberous sclerosis.
Again, don’t expect any help, additional information, or sympathy from the examiners.
The Pediatric Vignette
The pediatric vignette represents an entire hour of clinical pediatric cases.
It is anxiety-provoking for the adult neurologist, es- pecially if the candidate did not get enough exposure to pediatric neurology during the residency. Pediatric neu- rology is different from adult neurology and many adult neurologists are not exposed to pediatric cases during their practice.
As with the adult vignette, the pediatric vignette is a clinical pediatric neurology case open to discussion. The approach is again, read, think, and try to localize. One of the differences between the pediatric vignette and the adult one is that in pediatric neurology they are age- specific, i.e., certain disorders are typical of different age groups.
To an adult neurology candidate, the pediatric vignette can be a great source of apprehension, particularly if the candidate lacks familiarity with pediatric cases or if the candidate had limited exposure to pediatric cases during pediatric neurology rotation. Nevertheless, the impor- tance of this part should not be underestimated, as a pass- ing grade is a requirement for Board certification.
It is important, therefore, that the candidate devote am- ple time to a comprehensive preparation based on suffi- cient knowledge of pediatric neurology topics as well as case-based practice. In this section, we will review the
main categories of disorders in pediatric neurology, so that when you are presented with a case vignette you will be able to categorize it and formulate the most likely di- agnosis. It is worth mentioning again that, by and large, candidates are not expected to make the right diagnosis, rather to identify the category of the disorder, its temporal profile, and age group.
Localization in pediatric cases may not be as clear as in adult ones. Nonetheless, the candidate needs to make an effort to localize the lesion. The examiners are aware that the adult neurology candidate is generally less adept with pediatric cases. However, that should not deceive candidates about the examiners’ criteria for passing, which are based on the expectation of a basic knowledge of diagnostic and therapeutic issues in pediatric neurology.
The cases themselves tend to present basic diagnostic and therapeutic dilemmas, shying away from more com- plicated ones. Concerning suggesting ordering diagnostic tests or entertaining therapeutic options, it is generally advisable to maintain a cautious stance to avoid putting oneself into situations which may be difficult to resolve.
One example would be to be sure to mention the necessity of performing a computed tomography (CT) scan of the head prior to proceeding to a lumbar puncture. Diagnostic and therapeutic issues raised should cover all the basic questions raised in the case. Finally, though the content of the case will by its very nature differ from the adult vignette case, its format is very similar. Therefore, the principles outlined for the adult vignette apply for the pediatric vignette. As mentioned previously, the candi- date is expected to read, mentally highlight the most im- portant findings, localize, categorize, differentiate, and reach a reasonable diagnosis.
Age Categories
In pediatric neurology there are several distinct age groups that the candidate will need to keep in mind when approaching the case. These are
• Newborn (including the first month to six weeks of life).
• Infantile.
• Early (up to the end of the first year).
• Late (from the second year to school age).
• Childhood (up to 10 years).
• Adolescence.
In each age category there are certain types of clinical presentations that help in the process of determining what diseases should be considered in the differential diagnosis.
