The Beautiful Brain: The drawings of Santiago Ramón y Cajal


Public Domain,

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 from Japan – Person looking at smartphone in the dark, CC BY-SA 2.0,

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:

Continue reading

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Assessing Consciousness

This week’s Green Journal has an interesting fMRI study in which the authors identify specific lesional areas in the pontine tegmentum that are associated with coma. The study raises the possibility that such imaging could be useful in the diagnosis and prognosis of disorders of consciousness. This is important because, as the accompanying editorial points out, the risk of misdiagnosis is quite high in such disorders.

The assessment of consciousness offers yet another example of where adherence to protocols can improve clinical performance. There’s a tool called the Coma Recovery Scale – Revised that has been shown to be superior to clinical consensus in differentiating the vegetative state from the minimally conscious state. I added a “Rehab” entry to the clinical neurology resources in the menu above, with a link to this scale. It appears to be somewhat cumbersome, but worthwhile. After all, the stakes can be high in such cases, as decisions about the intensity of care may hinge on the neurologist’s assessment. Moreover, to the extent that such cases sometimes engender disputes among family members and between families and the clinical teams, employing a validated tool could be helpful in achieving consensus.

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Quick Followup on Torture

File:Rod of Asclepius2.svgA few years ago, I posted an essay about the medical and psychological, professions’ involvement in torture, particularly of detainees in the war on terror, and my own possible light brush with that world. Last week the New York Times ran a piece describing in more detail the role of physicians in not only carrying out the torture program, but in designing it. Again, this isn’t something that most of us will ever confront, but I think it’s worth noting the recent history and reminding ourselves every once in a while of our ethical obligations . . .

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Cui bono

Maria Popova’s Brain Pickings is a very interesting blog with articles and links relevant to what might be called popular neuroscience. As I’ve mentioned several times on this blog, however, one of my pet peeves with respect to some popular (and even academic) neuroscience is what Peter Hacker calls the mereological fallacy–the ascription to people’s brains properties that really apply to people. For example, brains don’t think; people think. Brains don’t see; people see.

As described by Hacker, the mereological fallacy applies to psychological predicates–feeling, thinking, knowing, perceiving, etc. A related practice, and a very common one (or at least, I notice it all the time), is the tendency to assert that something is good for our brains when it would be more appropriate to state that it is good for us, and above is a example of what I mean. It’s a 4 minute TED talk on the benefits of playing a musical instrument, and you can see in the title that the benefits supposedly accrue to the brain. The talk goes through some fMRI and PET evidence that many brain regions are involved in playing music, that this large-scale activity exceeds what is seen in other activities such as drawing, that it is associated with changes in brain structure, etc. Those are interesting findings vis a vis the neural correlates of musicianship, but are they really benefits? As a patient / lay person / citizen / non-neuroscientist, who cares that playing music is associated with certain patterns of fMRI activity? Or with enlargement of the corpus callosum? The more relevant benefits cited in this talk principally involve improvements in subjects’ memory and executive functions. Now those are potentially important findings, which suggest real benefits to us as people (beyond the obvious ones of giving pleasure and relaxation to ourselves and those listening).

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Involve the Palliative Care Team Early


Here’s a sad story about a family’s struggle with their young son’s fatal ordeal with New Onset Refractory Status Epilepticus (NORSE). NORSE is basically super-refractory status absent an obvious precipitating injury such as encephalitis. The main theme in this account is that the family felt under-informed along the way and then blindsided when it came time to discuss a transition to palliative care.

That frequent and clear communication is both imperative and fraught with challenges will be well-known to most everyone reading this. What I wanted to highlight from this article is actually the follow-on commentary by two neurocritical care physicians, who emphasize that palliative care shouldn’t be reserved for the situation where the patient is on the verge of death. Too often, our palliative care colleagues are consulted when there appears to be no viable means of curing the patient, death is imminent, and assistance is needed with terminal extubation and/or withdrawal of other life-sustaining interventions. However, and this needs to be done with sensitivity so as not to take away the family’s hope, earlier involvement of the palliative care team can be quite beneficial. The palliative care team can recommend measures to ensure the patient’s comfort even while full-on efforts to reverse the condition are underway. They can help clarify the goals of care, ensuring that the patient’s care plan comports with his values. And, if a transition to purely palliative care is eventually desired, it’s helpful for the relationships to have been established earlier in the hospital course and not at the last minute.

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Brain Death Resources

In light of the documented variability in the conduct of brain death evaluations around the country, and the ultra-high stakes, it’s extremely important for residents to know how to do this correctly. I recently became aware of a brain death toolkit published by the neurocritical care society; I added a link to it in Clinical Neurology Resources–>Neurocritical Care in the menu above. The toolkit has lots of helpful information, including links to the relevant guidelines, webinars, simulated video demonstrations, and an online training course developed by the Cleveland Clinic. This course requires a free registration and it’s very good; I highly recommend it. At the least, take the pre-test; if you struggle at all with those questions, they  you should definitely proceed with the course . . .

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