A Claw (Hand) by Any Other Name


By Photo: Myrabella / Wikimedia Commons, Public Domain, https://commons.wikimedia.org/w/index.php?curid=23806944

A timely Christmas blog post! At an MS2 session yesterday, we discussed the following practice question:

Blunt trauma to the elbow may lead to the development of:
a) Wrist drop
b) Weakness of the abductor pollicis brevis
c) Claw hand or benediction sign
d) Ulnar deviation of the hand
e) Poor pronation of the forearm

There ensued a somewhat confusing (because of my own confusion) discussion of what exactly is a benediction sign, is it different from a claw hand, what specific muscles are involved, etc. We’ll take a deep dive into that below, but first let’s just address the test question itself.

Blunt trauma to the elbow will most often injure the ulnar nerve. The ulnar nerve lies in a little groove between the medial humeral epicondyle and the olecranon. Partially flex your elbow to stretch the nerve a bit and then run your fingers in there and tap on the nerve; you’ll feel a little zinger in the medial hand. The median and radial nerves run deeper in the arm and aren’t typically injured by minor elbow (“funny bone”) trauma. So, we know that we’re looking at the answer choices for an ulnar nerve lesion.

When caused by a peripheral nerve lesion, wrist drop is due to injury of the radial nerve, so a) is out.

Abductor pollicis brevis is innervated by the median nerve, so b) is out.

Ulnar deviation of the hand (most apparent upon attempted flexion at the wrist) would also be due to a median nerve injury. Why? In a (proximal) median nerve lesion, there is unopposed action of flexor carpi ulnaris (ulnar nerve), pulling the wrist medially / to the ulnar side. In contrast, an ulnar lesion would result in unopposed action of flexor carpi radialis (median nerve) and would pull the wrist laterally / to the radial side. Thus, d) is out.

Finally, weakness of pronation is also a median nerve lesion, because pronators teres and quadratus are from the median and anterior interosseus nerves, respectively (the latter is a branch of the former). So that rules out e), leaving the answer as c) Claw hand or benediction sign.

So let’s talk about the claw hand. When attempting to open the hand with an ulnar nerve lesion, the thumb, index, and middle fingers extend normally. The 3rd and 4th lumbricals, which flex the metacarpophalangeal  (MCP) joints and extend the interphalangeal (IP) joints of the ring and pinkie fingers, are weak. Unopposed by those weak muscles, the radially-innervated extensor digitorum makes the MCP joints extend and the ulnar-innervated 3rd and 4th flexor digitorum profundi make the IP joints flex, creating a claw-like appearance on the medial side of the hand:


By Mcstrother – Own work, CC BY 3.0, https://commons.wikimedia.org/w/index.php?curid=11873645

But wait a minute! We just said that the ulnar nerve is injured at the elbow–shouldn’t the ulnar-innervated flexor digitorum profundus muscles be weak as well and NOT flex the interphalangeal joints and NOT cause clawing? Here’s where the nuances of neurology make things confusing. As described by Patten, not all sub-components of an injured nerve are affected equally. For example, sciatic nerve lesions can affect the peroneal (fibular) part of the nerve and spare the tibial part. In a proximal ulnar nerve lesion, the nerve fibers serving the flexor digitorum profundi can be spared, while the small muscles intrinsic to the hand are affected, resulting in the clawing.

Turning to the “hand of benediction”, I found conflicting descriptions in two authoritative texts. Preston and Shapiro describe it as an ulnar lesion that is synonymous with a claw hand deformity, as above and as per the test question.

However, in Brazis, the benediction sign is described as a problem in closing the hand with a median nerve lesion. The ulnar-innervated flexors of the ring and pinkie fingers function normally. The median-innervated flexors of the thumb and first two digits are weak and don’t flex:

Benediction Palsy ## Result of median nerve damage. Ulnar Claw due to ulnar nerve impairment has similar presentation. Both differ from Dupuytren's Contracture as may be passively straightened.


The orthopedist who created the animation below takes the Brazis position–that the hand of benediction is actually a median nerve lesion. He also asserts that only distal ulnar lesions spare the profundi and that lesions at the elbow would affect the profundi and not cause clawing; we covered that above. But with those caveats, I still think that this animation nicely shows what median and ulnar nerve lesions do to all of these confusing little muscles in the hands; for the purpose of learning the neuroanatomy, I think it’s definitely worth 6 minutes of your time:

We see that even authorities disagree on whether the hand of benediction is an ulnar / inability to open the hand problem vs. a median / inability to close the hand problem. In my quick research of the issue, I found this neat little paper that makes, I think, a compelling argument for the ulnar localization. They first consider the question of how one peacefully greets another person or moves to bless him; it’s with an open hand–not a fist! This suggests that a hand of benediction is properly an abnormal opening of the hand and not an abnormal closing. They go on to analyze ancient paintings and other depictions of St. Peter, finding that his medial MCP joints appear to be hyperextended, as one would expect if he had an ulnar lesion. So their theory is that the hand of benediction originated with an ulnar neuropathy in the original Pontiff.

Thus it would seem that Preston and Shapiro have it right, but if any neuromuscular experts happen to be reading this, I’d certainly appreciate your comments! More important for the student of neurology, we should remember that all of the above confusion stems from the use of historical nomenclature and, in this instance, from the inherent limitations of multiple choice test questions. In real life, the patient doesn’t come to you asking for your assessment of  her “hand of benediction” (with a list of choices); she comes stating that her hand doesn’t look right, or is weak, or became weak after bonking her elbow, or something along those lines. Neurological examination, including motor, reflex, and sensory functions, would make localization fairly straightforward. Then, when recording the findings, it’s best to describe them carefully, localize them to the appropriate nerve, root, etc. and develop a differential diagnosis, staying away from ambiguous terminology. The question isn’t whether the patient has a claw hand or a hand of benediction or whether those are truly synonymous. The question is whether the patient has an ulnar nerve lesion, a median nerve lesion, or some other lesion, and why.

Just to reinforce this last point about terminology, consider the evaluation of level of arousal. You’re the resident cross covering overnight and you’re called to evaluate a patient for a change in mental status. The morning progress note states that he was “obtunded”. Now, Plum and Posner do have a specific definition for that term, but the reality is that people use words such as “lethargic” and “obtunded” in varying ways; when you evaluate the patient, you can’t be sure from that one word what he truly looked like before (tip: ask the nurse!) It’s much better to describe the patient’s condition in more detail: “On exam, his eyes were closed. To gentle sternal rub and voice, he opened his eyes, made brief eye contact, and followed some simple commands, going immediately back to sleep when stimulation ceased”. With that kind of description in the chart, the next person can make an accurate assessment of whether the patient’s condition has changed.

Well, that was fun! Again, if anyone has more insight into the matter, just leave some comments below.

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I’ve always had a place in my heart for pathology—the fundamental basis for allopathic medicine. By this I mean that in diagnosing and treating disease, we’re concerned with the structure and function of the body’s organs and systems, their pathological disruptions, and the biochemical and genetic bases for such. I don’t mean to downplay the importance of patients’ emotional experiences, existential challenges, family dynamics, and other personal and social aspects of health and disease; these are important too. But what we are not concerned with is balancing the four humors or regulating the flow of qi.

Even in psychiatric practice, one of the first tasks in any diagnostic evaluation is to rule out an “organic” cause of the patient’s mental or behavioral dysfunction. This raises extremely interesting questions about structure-function relationships in the brain—is there truly a difference between “organic” and “psychiatric” disease, or is the latter just a brain disorder where the underlying structure-function relationships haven’t been fully elucidated? These sorts of questions are in part what drew me, and many others, to neurology, but that’s a topic for another day.

The bottom line is that if one is going to diagnose and treat disease in the allopathic paradigm, one must have at least some grasp of pathology. I actually spent a year as a pathology “fellow” between my M2 and M3 years and can attest that it was very helpful in understanding the diseases I later saw on the wards. There’s a huge difference between say, reading about congestive heart failure vs. actually squeezing with one’s own fingers the edema fluid from the lungs of a deceased CHF patient, or feeling and hearing the scalpel scrape and cut through his atherosclerotic coronaries. Similarly, directly inspecting a brain’s purulent meninges, its atrophic gyri, its depigmented midbrain, its foci of infarction, etc. brings a greater depth of understanding than simply reading about these conditions or viewing the pathologies on MRI.

To that end, I want to encourage residents to take advantage of learning opportunities in neuropathology. At our institution, we’re fortunate to have a neuropathologist with over 30 years of experience teaching residents. He has dozens of gross “museum cases” and clinico-pathological case reports and hundreds of slides, all with accompanying explanatory material for self-study. And we have brain cutting twice each week, which also serves as a reminder that we should refer our deceased patients for autopsy when appropriate—again, MRI doesn’t have all of the answers.

The specific purpose of this post is to bring to the residents’ attention an outstanding web resource for neuropathology. It’s an online textbook / lecture series / self-assessment tool developed by Dr. Dimitri Agamanolis of Akron Children’s Hospital and Northeast Ohio Medical University. The meat of it is a series of chapters on neurocytology, hypoxic / ischemic injury, CNS infections, demyelinating diseases, etc. Most of the chapters have an embedded video lecture that’s also accessible on Vimeo, but the material can be perused by reading alone if desired. Clicking on the thumbnail photomicrographs reveals enlargements with detailed captions. Most chapters have an associated quiz, and I think that working through all of the chapters and all of the quizzes would be great preparation for the RITE and boards. This is a very high-quality resource that Dr. Agamanolis has graciously published to the web for free; I wish to extend to him my thanks!

(I added a link to the site in the main menu above, under Clinical Neurology Resources→General Neurology).

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Von Hellerhoff – Eigenes Werk, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=20045205

Question: An 8 year-old girl presents with cognitive delay and incoordination. What is the diagnosis? See below for the answer.

It goes without saying that neurologists must learn to interpret radiographic images; residents look at so many CTs and MRIs that it’s almost impossible not to develop some competence in this area. It’s important to develop, like our neuroradiology colleagues, a systematic approach to image interpretation–one can’t just scan the DWI or FLAIR images for areas of bright signal. Moreover, and as the senior residents are well aware, the RITE has a bunch of unusual imaging questions like the one above; indeed the exam includes a whole booklet of questions based on radiographic and pathological images.

Residents might find a recent Continuum issue on neuroimaging to be a helpful resource. It has an introductory chapter on MRI physics, and goes on to cover advances in stroke imaging, imaging patients with epilepsy, brain tumors, spinal cord disorders, etc.

There’s a particularly good chapter on imaging congenital malformations. This high-yield chapter covers a lot of topics pertinent to both pediatric neurologists and adult neurologists taking the RITE and boards (i.e. just about everybody). In addition to being a very good issue in general, that chapter would serve very well for test preparation.

Finally, here’s a link to an interesting podcast episode from The Guardian’s Science Weekly (episode 28). It covers the history of MRI and includes a digestible explanation of MR physics.

Answer: Dandy-Walker malformation. The cerebellum is hypoplastic. The fourth ventricle and posterior fossa are enlarged, and the cerebellar remnant is displaced superiorly.

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Exam Videos

Dr. Hal Blumenfeld’s book, Neuroanatomy through Clinical Cases, is a great introductory text for neurology residents. It’s comprehensive, yet quite readable, with lots of superb drawings and illustrative cases. I think it occupies the space between Berkowitz’s Clinical Neurology and Neuroanatomy, (a new book that I recently reviewed here), and Brazis’s classic, Localization in Clinical Neurology. The former is particularly well-suited for beginners—students, interns, and junior residents who want a concise introduction to their future specialty; we give a copy to our PG1s. The latter is still my go-to for what I call “micro-localization”—when I need to refresh my memory on some precise neuroanatomical detail. It’s best digested in small chunks; we’re using it for book club this year.

Blumenfeld fits nicely between those two. It’s longer and more detailed than Berkowitz, but the layout and case discussions make it easier to digest than Brazis. Our residents are using it for their resident-led lecture series this year.

Recently, I discovered that Dr. Blumenfeld created an online companion to the book in which he demonstrates the neurological exam in a series of short videos. These are available on the web, for free, here. There’s also a longer video that includes an entire exam, but that one is gated; I assume you get access if you buy the book.

These exam videos are a great resource—there’s a big difference between reading about how to do the exam vs. seeing it done by an expert. For example, embedded below is the video on oculocephalic testing, and I added a link to the main webpage with all of the videos on the menu above, under Clinical Neurology Resources → General Neurology.

Two other video resources I’ve mentioned before (and that are also accessible via the menus above) are the Neuro-Ophthalmology Video Education Library (NOVEL) and the International Parkinson and Movement Disorder Society video library. The latter one requires a membership, but this is free for residents; the signup page is here.

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Pointing Towards Virtue

Image result for finger pointing at the moon koanThe 2017-18 year is underway, and this is usually the time for orientations, “boot camps”, links to useful resources, etc. I have some some of the last queued up for soon-to-follow posts, but first wanted to address a deeper matter.

A few weeks ago, I received a survey about character education in residency. It was comprised of questions like “Where in your residency program do trainees learn virtues such as honesty and integrity?” I found this line of questioning to be exasperating on a few counts. First, residents are adult learners—not schoolchildren. I presume that they will have developed their moral virtues well before entering residency training (at an average age of around 30). When and from whom do they learn moral virtue? Years prior, from their parents, school teachers, coaches, clergy, etc.

Moreover, to whatever extent people are lacking in certain virtues by the time they reach adulthood, they are not going to acquire them in a residency program—that ship has sailed, I thought.

Finally, I resented the implication that moral virtue could be codified as a set of behaviors or “competencies” to be checked off a list as part of yet another training milestone. If anything were to exemplify what I previously termed “competency theater“, this would serve splendidly.

And yet, as we roll into month #2 of this new year, I think that my initial reaction to this moral inquiry may have been too flippant. Consider that the Greek origin of  “character”, kharássō, means to scratch or engrave. It implies a process and not a fixed state—a process that, over time, imparts one with distinctive traits. Are residents not amenable to ongoing engraving of character? Aren’t we all?

Furthermore, it perhaps should not be taken for granted that virtues developed in the context of family life, grade school, etc., will always manifest in the context of residency training. This might be especially true when the virtue hasn’t really been tested before. Some young people might not yet have been in situations where they must choose whether or not to subordinate their own interests to those of another, or whether to be fully honest at the risk of great personal embarrassment or inconvenience. We all presumably learn about the moral virtues during our upbringing, but actually becoming virtuous in daily practice is the real challenge (and one that I don’t claim to have fully achieved).

There’s a Buddhist teaching, depicted above, that applies well to this crucial difference between the abstract knowledge of moral virtues versus their exercise: Imagine that someone is trying to show you the moon by pointing to it. One should not focus too much on the finger! With that caveat, following are some examples of how character is tested in the context of residency training; I hope that residents will find them to be useful pointers.

Humility. Neurology has become a very interdisciplinary field. Forget about the simplistic old saw that “The nurse can be your best friend or your worst enemy.” Today, we work with nurses, pharmacists, physical therapists, occupational therapists, speech/language pathologists, respiratory therapists, dietitians, social workers, case managers, etc., etc. Many of the above have graduate-level education, some doctorate-level. Most have years of experience—certainly more experience in their respective fields than a resident has in neurology. And regardless of age, each person is an expert in his or her area. I’m now PGY18 and have cared for thousands of stroke patients but I’m not as good at assessing the functional status of a stroke patient as my OT colleagues. And I’ll never be as good as they are, just like I’ll never read brain MRIs quite as well as our neuroradiology colleagues.

Therefore, when a nurse, therapist, pharmacist, or other member of the treatment team raises a concern or provides new information, it’s important to listen, consider the information on its merits, and integrate that into the case formulation. We must resist the urge to reject the information because it came from someone other than a physician (arrogance), because it doesn’t comport with our previous understanding of the patient’s condition (anchoring bias), or because acknowledging it would mean that we were wrong about something (denial).

That last point deserves emphasis: It’s OK to be wrong, as long as we remain open to correction! I know that doesn’t comport with our years of high school → college → medical school acculturation, where the point of the game, it often seemed, was to supply correct answers. But now we’re in a very different setting, where there are fewer right / wrong answers to be supplied and more assessments and plans to be made. EVERYBODY makes a sub-optimal judgment from time to time and it’s especially ridiculous to think that a PG2-4 neurology resident should be perfect in this regard. Our main mission is to take the best possible care of our patients. If there’s a piece of information or a perspective that might advance our patient’s care, we want to incorporate that as soon as is appropriate. And besides, resisting an opportunity to optimize a patient’s care or correct a mistake is much, much more injurious to a physician’s reputation than is the fact that he or she was once wrong about something. 

Honesty. Imagine a case1Perhaps this scenario seems too obvious or egregious to be true, but trust me—this kind of thing happens. where a patient presents to the ED one afternoon with a thunderclap headache and left-sided tingling. Exam is normal. CT shows no hemorrhage. CSF is colorless. Because of the focal symptoms and high-risk nature of the case, the patient stays in the ED’s observation area pending an MRI. The plan is to treat the pain, observe for some hours, and, if the clinical course and MRI/A/V are reassuring, discharge home with outpatient follow-up.

The next morning, the patient feels much better but the MRI still hasn’t been done. The ED resident informs you that the patient can only stay in the obs unit for a couple more hours—if more time is needed for the workup to be completed then he’ll need to be admitted. You make some phone calls and arrange for your patient’s MRI to be done next.

The ED resident calls again to report that the MRI is done and time is running out for an obs stay–a decision must be made now. You look at the MRI yourself (kudos!) and it looks OK. The prelim read is normal too. You call up your attending to explain that the patient is teed up for discharge, and he asks, “Do we have a final read on the MRI?”

Aaaargh! A final reading is going to take more time, and then you’ll be stuck admitting the patient only to discharge him a couple of hours later—a hassle for you both. And really, what’s the chance that the final read is going to be substantially different than the prelim? So, “Um, yeah, the MRI was read as normal,” you say. It’s sort of true, although not really. The patient goes home. And then the neuroradiology attending calls your attending a few hours later to report that they found a 2mm acomm aneurysm on the MRA. “Did that patient get discharged? We may need to bring him back . . .”

Always be honest—it’s best for the patient and, although it might not always seem that way in the moment, best for your reputation as well.

Kindness. It can be seemingly difficult to practice kindness while immersed in a challenging training program, or while running a busy clinical practice, or while managing a chaotic (e.g. child-rearing) household, or . . . you get the idea. But here’s a nice paradox: Being kind to your patient or colleague (or a family member, or perhaps especially to a stranger) is a reliable way to reduce both their suffering and yours.

And it can be really easy—I’m not talking about committing to 10 hours a week of volunteer work on top of everything else on your plate. Very simple things can go a long way: You took off the patient’s socks to check for Babinski’s sign? Put them back on. Carefully. Offer to cover her back up. Don’t forget to turn the TV back on if you turned it off. Did the nurse come in and silence the beeping IV while you assessed the patient? Thank him! Right then and there, in front of the patient. When the patient sees that you respect your colleagues, she’ll know that you respect her too. She will feel better about her care, and she will remember! She may not remember half the things you educated her about with respect to her stroke, but she *will* remember that you were kind. And once in a while, a patient will express to you, long after the fact and long after you’ve forgotten about it, her appreciation for that kindness. These are among the moments that sustain a medical career.

Obviously, this is a very limited list of virtues; please feel free to offer additional thoughts in the comments. I’d also be happy for interested residents to author guest posts. If nothing else, I hope this will get us thinking explicitly about the kind of physicians, and indeed the kind of people, we want to be.

Notes / References   [ + ]

1. Perhaps this scenario seems too obvious or egregious to be true, but trust me—this kind of thing happens.
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The Beautiful Brain: The drawings of Santiago Ramón y Cajal


Public Domain, https://commons.wikimedia.org/w/index.php?curid=612581

Santiago Ramón y Cajal is one of the founding fathers of neuroscience. He was the foremost proponent of the neuron theory–that the nervous system is composed of interconnected but individual neurons as opposed to a continuous reticulum of nervous tissue. This conclusion stemmed from his use of the Golgi stain, which randomly stains only a fraction of the cells in a tissue sample, allowing for their individuation. He and Golgi shared a Nobel prize for this work.

Ramón y Cajal was a fantastic artist whose drawings elucidated the structure of the nervous system; the picture above shows two Purkinje cells and a few granule cells from a pigeon cerebellum. There’s now a traveling exhibit of his neuroanatomical work, with an accompanying book. It looks to be a terrific exhibition; here’s a New York Times review, which includes several more wonderful drawings. If you happen to live near one of the tour stops it might be well worth a visit.

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A Zebra for Our Times: Transient Smartphone Blindness

By Japanexperterna.se from Japan – Person looking at smartphone in the dark, CC BY-SA 2.0, https://commons.wikimedia.org/w/index.php?curid=47395025

Here’s a neurological oddity to be aware of: Transient smartphone blindness. Per a case report in this week’s Green Journal:

When a patient lies on one side, the ipsilateral (lowermost) eye becomes functionally occluded (e.g., by a pillow) and its retina maintains adaptation to the ambient light level or may become relatively dark-adapted. Meanwhile, the contralateral (uppermost) eye becomes light-adapted while it is used to view the device, which illuminates the retina to a greater degree than ambient light (this differentiates the scenario from book reading). After the patient stops using the device and transitions to binocular vision with both retinae exposed to dim ambient light, she perceives normal vision with the dark-adapted eye but temporary blindness in the light-adapted eye.

It’s easy to see how this could be misdiagnosed as a retinal TIA, retinal migraine, functional disorder, or even MS as per the case report.

Update: Here’s an interesting and humorous commentary on the phenomenon, courtesy of Dr. Michel Accad.

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RITE Review

In follow-up to the publication of the textbook reviewed below, Dr. Berkowitz created a Facebook page and is posting board-style review questions on it. I think the plan is to post one per day. Have fun!

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Neurology Book Report

Image result for clinical neurology localization-based berkowitz“What should I read?”

It’s a common question from students, especially future neurology residents, as well as advanced practice providers and allied health professionals set to care for neurological patients. It’s a hard question to answer because neurologists often rely on a variety of texts for different purposes. Reference texts such as Adams and Victor’s or Bradley and Daroff are too encyclopedic to recommend for straight-through reading unless the intended use is as a sleep aid (the latest edition of Bradley’s weighs in at 2348 pages). Brazis’s Localization in Clinical Neurology is indispensable for refining one’s localization skills, but isn’t suitable for a beginner’s approach to the field. Closer to the mark is Patten’s Neurological Differential Diagnosis. It’s quite readable, full of anecdotes, and suitable for the beginning neurologist. The drawings are marvelous. As big a fan as I am, this text is rather dated, not having been updated since 1996.

Clinical Neurology and Neuroanatomy, by Harvard neurologist Aaron L. Berkowitz, threads the needle perfectly. This isn’t surprising; Dr. Berkowitz’s CV shows over a half dozen teaching awards. He’s authored several other textbooks and  he directs the Global Neurology Program at Brigham and Women’s. I suppose nothing develops one’s neurological skills quite like practicing and teaching neurology in resource-limited areas.

Like many neurology texts, this one is divided in two parts, the first on the approach to patients with the different types of symptoms and the second on the neurological diseases themselves (epileptic, vascular, etc.) The first chapter includes a very important discussion of the neurological method (my own take on that is here), including a helpful and under-appreciated mention of localizing neurological disease to specific structures (e.g. Broca’s area on the left) vs. tissue types (peripheral myelin vs. axons) vs. systems (pyramidal, extra-pyramidal, etc.) I also like how well Dr. Berkowitz marries the neuroanatomical descriptions, say of the visual pathways, to the approach to to the patient with, in this example, visual loss.

I found much else to like in this text:

    • There are great explanations of tricky material such as strabismus, cover testing, and the use of the Maddox rod and optokinetic drum. There’s a good introduction to peripheral neurology and EMG. The chapter on neuromuscular junction disorders has an excellent description of low- and high-frequency repetitive nerve stimulation in myasthenia gravis and Lambert-Eaton myasthenic syndrome.
    • The fact that it was written by a single author is not only impressive, but also lends excellent consistency to the text, with emphasis on clinical pearls and the avoidance of minutiae. For example, the stroke chapter describes the role of the ABCD2 score, contains discussion of the difficult issue of when anticoagulation might occasionally be used in the acute setting, and describes the uncommon but important phenomenon of amyloid spells.
    • It’s very contemporary, including descriptions of relatively new entities such as encephalitis associated with anti-LGI1 antibodies and their association with faciobrachial dystonic seizures and the use of the HINTS exam in differentiating central from peripheral vestibulopathy. I was also pleased to see some references to the role of cognitive bias in diagnosis, such as a warning to avoid premature closure when attributing a patient’s delirium to “toxic-metabolic” causes.
    • The drawings are excellent, and there is much integration of modern neuroimaging into the anatomical and clinical discussions.
    • The tables are very clinically-oriented, rather than just listing long differential diagnoses as some texts do. For example, there’s a very good table comparing and contrasting the various Parkinsonian syndromes and another describing the early, late, and treatment-related complications of HIV.
    • There is judicious use of mnemonics. I’ve seen these get out of hand in some texts, especially board review books, but here they are relatively few but easy to remember. Example: The vein of Trolard is on top; Labbé is lower and more lateral.

I’m hard-pressed to identify a weakness here. Probably the most difficult chapter for the beginner will be the one on the upper extremity roots, plexus, and nerves; I think that’s just the nature of the beast. As I’ve mentioned before, there’s a great course on the brachial plexus available on the AAN website (registration required). There’s a very brief introduction to EMG and nerve conduction studies; it would be nice to see a similarly brief introduction to the technical aspects of EEG.

Simply put, this is a great introduction to clinical neuroanatomy and neurology and I recommend it highly.

Disclosure: The editors at McGraw Hill provided me a copy of the text for the purpose of this review, but I received no compensation for it and retain full editorial control.

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On the Interpretation of Neuroscientific Findings

By now, many readers will know that I’m a devotee of Peter Hacker’s Wittgenstein-infused critique of neuroscientific research. I recently came across a podcast of a lecture that he gave on the topic and the corresponding YouTube video above. Here’s the iTunes podcast link (it’s episode #92). So, if you’re interested to learn more about this but don’t want to commit to reading the whole tome, the lecture will get you the gist of it in just under an hour.

Here, I’ll take a stab at applying this kind of analysis to newly-published work regarding the integration of brain activities while driving and listening to different kinds of audio. But first it’s necessary to review some foundational research on “split brain” patients. Once upon a time, severe generalized epilepsies were treated with commissurotomy (corpus callosotomy), the idea being that if the epileptic discharges could at least be confined to one brain hemisphere, this would be less disabling (and life-threatening) than if the patients kept having generalized seizures. Starting in the 1960s, Profs. Roger Sperry and Michael Gazzaniga published some extremely interesting studies on these patients. Here’s a diagram of one of their experimental setups:

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