Now, That’s What I Call High-Yield: Neurology, Part 1
- Jun 04, 2019
Neurology is a behemoth of Step 1 studying. The amount of material is perhaps greater than in any other body system. After all, it does encompass a four-year residency while the broad strokes of internal medicine only necessitate three. My usual caveat to all high-yield reviews is especially true here in neurology. Trying to condense this enormous quantity of material into a few simple high-yield topics is as impossible as understanding Wernicke’s word salad.
The approach to neurology study for Step 1 will work just as it does in other section. Build a strong foundation in normal anatomy and physiology of the system, and build on top of that framework with the pathology. Neuroanatomy is extremely important. So much of the practice of neurology is “localizing the lesion” based on a patient’s neurological deficits. This practice would be impossible without having a very firm handle on the anatomic layout of the brain, brain stem, spinal cord, and peripheral nervous system. Though it might be tricky to hold back, only tackle pathology when you get knowledge of neuroanatomy to a sufficient level of understanding.
We will divide high-yield Neurology into 2 sections. Don’t forget to check out the High-Yield Step 1 Appendix for a breakdown on the tracts of the spinal cord, for you will definitely be tested on them.
Dopamine Pathways (6.5) – Dopamine…the chemical that floods our nervous systems everytime we get a question right on Tutor Mode, and that green check pops up. This neurotransmitter is involved in so many of the body’s functions, and to keep them straight, it certainly helps to remember the four different pathways that utilize it. The aforementioned one is the mesolimbic, responsible for drug reward and addiction; it’s overactive in schizophrenics. Positive symptoms of schizophrenia, those targeted by dopamine antagonists, act here. Decreased activity of the mesocortical pathway creates negative symptoms of schizophrenia. The nigrostriatal pathway is connected to the substantia nigra, and therefore, decreased activity leads to Parkinsonism. Lastly, the tuberoinfundibular pathway is the dopamine tract involving prolactin. Recall that dopamine is occasionally known as Prolactin inhibitory factor; decreased dopamine means increased prolactin, leading to sexual dysfunction and galactorrhea.
Homunculous and layout of cortex (8.5) – Neuroanatomy! Huge topic! Understanding the layout of the cerebral cortex, the blood supply to each region, and the almighty Homunculus will pay incredible dividends. In the cortex, your most important zones are as follows: the motor cortex in the frontal lobe; its neighbor just behind the central sulcus, the primary sensory strip in the parietal lobe; the visual cortex in the occipital lobe; and the entire language pathway, from the comprehension center, Wernicke’s area in the temporal lobe, along the arcuate fasciculus, ending in the motor center of Broca’s area in the frontal lobe.
The sensory and motor strips have fascinating distributions in terms of matching body parts to brain chunks. You don’t need to have the finer points of the homunculus down pat. Just know that the most medial part of the brain is responsible for lower extremities, arm and hand at the superolateral section, and face most lateral.
Cerebral Perfusion and Artery Zones
Cerebral perfusion and artery zones (9) – So many questions about the brain revolve around blood flow. There’s not a ton of oxygen reserve in the brain, so when blood flow is compromised, it’s only a matter of time before areas become ischemic. This leads to a stroke, the second most common cause of death worldwide. Probably most devastating is a compromise to the middle cerebral artery (MCA), as it supplies major regions of the cortex involved in speech and movement of the upper extremities. The anterior cerebral artery supplies the cortical region responsible for lower extremities. An issue with posterior circulation, whether the posterior cerebral artery, or one of the cerebellar arteries, would be the one to affect the visual cortex.
Cranial Nerves and Reflexes
Cranial nerves and reflexes (9) – Part of the bedrock of medical education, the cranial nerves aren’t going anywhere. As we continue to sing the praises of knowledge of neuroanatomy, knowledge of the cranial nerves, their locations, and their functions is absolutely essential. Esoteric knowledge of all the different nucleii of cranial nerves in the brainstem is probably a bit more than you need to know. But you should expect to see the classic reflexes (e.g., pupillary, corneal, gag) on Test Day.
Some lesser mentioned (non-bulbar) but important cranial nerve functions: Baroreceptors feed afferent signals to the brain via cranial nerve IX, and exert their efferent effects via cranial nerve X. The vagus is responsible for so much! Responsible for vasovagal reflexes, digestion, control of the vocal cords, and parasympathetic innervation of the heart, this nerve has reach is nearly every major body system.
Spinal Cord Anatomy and Lesions
Spinal cord anatomy and lesions (10) – Find a picture you like that displays a cross-section of the spinal cord. Then stare at it and commit it to memory. Don’t be afraid to put a lot of time into this. For starters, check out our review of the most important tracts of the spinal cord. Once you understand where these tracts lay in the spinal cord, where they cross over to the other side of the body, and where their synapses take place, you will be ready to take any spinal cord lesion or trauma, and figure out what sort of phenotype it would create. More importantly, you can take a patient with a particular set of symptoms, and perform the essential task of neurology, localizing the lesion.
Looking for more Step 1 high-yield study tips? Check out the med student’s guide to receptors and high-yield Step 1 study of the musculoskeletal system.