Errors in First Aid for the USMLE (2007): Neurology

As always… all suggestions, additions, corrections are welcome.

Neurology

  1. P.345, Basal ganglia
    1. I think this image is confusing and could benefit from a few additions. Specifically, I think it should be made clear that neurons from the SNc are synapsing on neurons in the Striatum. The Striatal neurons are currently labeled as “Putamen” which would lead to confusion if a test stem referenced the “striatal neurons” that are the sites of Huntington’s lesions.
    2. I think it is appropriate in this section to repeat that Dopamine is inhibitory through its D2 receptor (currently unmentioned) and stimulatory through its D1 receptor.
    3. The light and dark shading of the pathways is not very intuitive, and I think a return to + and – signs might be worthwhile.
  2. P.349, Spinal tract anatomy and functions
    1. Under 3rd-order neuron, “sensory cortex” is listed for the Dorsal column-medial lemniscus tract. The third order neuron is actually that neuron originating in the thalamus (receiving the 2nd-order neuron as described) and then projecting to the sensory cortex. It is the 4th order neuron (within the sensory cortex) that is the end-point of this tract and responsible for any conscious experience. “sensory cortex” should be changed to “ascends from VPL of thalamus to sensory cortex.”
    2. This same criticism applies to “sensory cortex” listed for Spinothalamic tract.
  3. P.357, Visual field defects
    1. The 6th bullet for “Left hemianopia with macular sparing” should include the “(PCA)” since this is the most commonly cited cause. The image should also include a bar across the fibers in the posterior part of the optic radiation. As it stands, “6” is the only number in the figure without a bar marking the site of the disruption.
  4. P.359, Aphasia
    1. Just for the repetition, I think the following should be added here:
      1. Broca’s (44,45)
      2. Wernicke’s (22)
  5. P.363, Primary brain tumors
    1. Childhood peak incidence
      1. F. Pilocytic (low grade): this tumor is correctly described as being found most often in the posterior fossa, however, it is drawn in the anterior fossa and supratentorial. Further, the image of the brain is backwards from what is traditionally shown, which may have led to some confusion during the illustration.
  6. P.364, Tabes dorsalis
    1. Because space is not an issue here and the term has not been used recently, I think it might be worth extending “DTRs” to “deep tendon reflexes”.
  7. P.365, Brown-Sequard syndrome
    1. First bullet point is followed by “not shown”. Similarly, the fifth bullet point is also not shown on the diagram. I do not understand this, since the territory of “Ipsilateral UMN signs” is identical to the territory of “Ipsilateral loss of tactile, vibration, proprioception sense”. It seems the labeling could read “1,2” instead of just “2”. My point is similar for bullet points “4,5” instead of “4” when describing the territories of “Ipsilateral loss of all sensation at level of lesion” and “LMN signs at level of lesion”.
  8. P.366, Facial lesions
    1. Instead of the current mnemonic “ALexander Bell with STD: AIDS, Lyme, Sarcoid, Tumors, Diabetes” I suggest the shorter “BLASTeD: Bell’s palsy from Lyme, AIDS, Sarcoid, Tumors, Diabetes”. A small change, but somewhat easier to remember. Or, if you like, “Bell-LASTeD“.
  9. P.367, Parkinson’s disease drugs
    1. When describing bromocriptine, I think it’s important to say that it is not simply a “partial dopamine agonist”. It is instead a selective dopamine agonist at the D2 receptor, and has its action not in stimulating the direct pathway of the basal ganglia, but instead suppresses the indirect pathway.
  10. P.370, Anesthetics – general principles
    1. The line beginning “Drugs with [up arrow] solubility…” could use a little changing. I suggest beginning with the reciprocal relationship between MAC and potency, followed by the conclusion. I also believe that MAC is not Minimal Anesthetic Concentration but Minimal Alveolar Concentration. The distinction is important as the two are not the same.
      1. MAC = Minimal Alveolar Concentration. Potency = 1/MAC. [up arrow] solubility = [up arrow] potency = [down arrow] MAC.
  11. P.371, Intravenous anesthetics
    1. I propose an alternative for the mnemonic “B.B. King on OPIATES PROPOses FOOLishly” for memorizing Barbiturates, Benzodiazepines, Ketamine, Opiates and Propofol.
      1. KOPs keep them BEhind BARs: Ketamine, Opiates, Propofol, BEnzodiazepines, BARbiturates.
        1. Bonus: …where they are put to sleep by IV anesthetics.
  12. P.371, Local anesthetics
    1. In the second bullet point, when dealing with the order of nerve blockade, the small myelinated/unmyelinated fibers of the ANS could be included “temperature > ANS > touch”

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9 Responses to Errors in First Aid for the USMLE (2007): Neurology

  1. Fernando says:

    Point 10. MAC is spelled out minimum alveolar concentration or minimum anesthetic concentration or minimum alveolar anesthetic concentration. http://www.anesthesia-analgesia.org/cgi/content/abstract/96/1/119?ijkey=794bcc4624e340c6ca4616924efbdd98b93ea286&keytype2=tf_ipsecsha

  2. Nelson says:

    Regarding #9 Bromocryptine: A D2 partial agonist will *stimulate* the indirect pathway, leading to inhibition of movement.

  3. Fernando says:

    page 372. Everything I have read says there is no pharmalogical antidote to succinylcholine (especially not an acetylcholinase inhibitor like neostigmine, which is what is written under phase II of the depolarizing NMJ blocker succinylcholine).

  4. Fernando says:

    p.357. Testing extraocular muscles (diagram). LR & MR are labeled correctly, associated with temporal and nasal respectively, but SR & IO are switched, as are IR & SO.

    Medial (towards nose)
    1)Elevation, adduction:
    Superior rectus
    2)Adduction:
    Medial rectus
    3)Depression, adduction:
    Inferior rectus

    Lateral (towards temple)
    1)Elevation, abduction:
    inferior oblique
    2)Abduction:
    Lateral rectus
    3)Depression, abduction:
    Superior oblique

  5. Eric Brinton says:

    p. 357 is correct regarding extraocular muscle testing. You are getting confused between how the muscles move the eye and how the muscles are tested. In First Aid, it is talking about how the muscles are tested. In testing, for instance, you have the patient look down and in to test the SO. However, the superior oblique muscles causes the eye to move down and out in real life. I don’t have time to go into why, but in Gray’s Anatomy talks about it.

  6. Elian says:

    Page 350
    the illustration labeled claw hand looks actually much more like benedict’s hand which is a result of injury to the median nerve ( when the patient is aked to make a fist the index and middle fingers remain straight while the ring and the little fingers flex)

    Claw hand is a result of ulnar nerve injury and results from unopposed action of flexor digitorum profundus (innervated by the median nerve). Because of this the DIP joints of the idex and middle finger should also be flexed !!

  7. David Kammer says:

    the above comment about the claw hand is correct, here is a better picture or claw hand from MedlinePlus:

    http://www.nlm.nih.gov/medlineplus/ency/imagepages/9196.htm

  8. zfuw xhjzlqnyu gspt ypdusc qxvj gxdiop vzpr

  9. monokini says:

    swimsuit…

    Errors in First Aid for the USMLE (2007): Neurology « the rumors were true…

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