Locate the Lesion
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www.npjournal.org The Journal for Nurse Practitioners - JNP 409 Neurology is a four-letter word in most primary care settings because we cannot “see” it. When some- one comes into our office complaining of a neurolog- ic symptom, we cannot run a blood test or an x-ray to tell us definitively what is wrong. Unlike other specialties such as cardiology, in which dysrhythmia is seen on electrocardiogram and congestive heart failure is shown on x-ray, or in primary care, in which hyperlipidemia is identified through blood levels, neu- rology is much more inferential. We can look at mag- netic resonance images and computed tomographic scans or check electroencephalograms and spinal taps, but often these studies only give us supportive data, not a conclusive diagnosis. Or they are used to rule out other diagnoses or problems, rather than rul- ing in our leading suspected diagnosis. Thus, the diagnostic dilemma. Many neurology diagnoses are still primarily a clini- cal diagnosis made from history and physical assess- ment, so it is important to understand what you are seeing. I start by breaking it down into two basic cat- egories: central nervous system (CNS) and peripher- al nervous system (PNS) findings. The CNS comprises the brain and spinal cord; the PNS is everything else. Remember that the cranial nerves are considered part of the PNS but integrate into the CNS by associated nucleuses. Thus, cranial nerves can sometimes give a confusing picture and need to be taken in context with the clinical picture. Spasticity, increased tone, hyperreflexia, and extensor plantar responses tend to support a CNS process. Hypotonia, flaccidity, or diminished reflexes are associated with PNS disorders. Sensory dysesthesias or motor weakness of the CNS is more likely to be hemidysesthetic or hemi- Locate the Lesion DIAGNOSTIC TIPS Barbara Bishop Major anatomical features of the human nervous system include the brain, the spinal cord, and each of the individual nerves. The brain and spinal cord make up the central nervous system (CNS) and all the nerves and their branches make up the peripheral nervous system (PNS). Nerves originating from the brain are classified as cranial nerves, and nerves originating from the spinal cord are called spinal nerves. Source: Thibodeau GA, Patton KT. Anatomy and physiology. 5th ed. St. Louis: Mosby;2003.p.343.
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Transcript of Locate the Lesion
www.npjournal.org The Journal for Nurse Practitioners - JNP 409
Neurology is a four-letter word in most primary caresettings because we cannot “see” it. When some-one comes into our office complaining of a neurolog-ic symptom, we cannot run a blood test or an x-rayto tell us definitively what is wrong. Unlike otherspecialties such as cardiology, in which dysrhythmiais seen on electrocardiogram and congestive heartfailure is shown on x-ray, or in primary care, in whichhyperlipidemia is identified through blood levels, neu-
rology is much more inferential. We can look at mag-netic resonance images and computed tomographicscans or check electroencephalograms and spinaltaps, but often these studies only give us supportivedata, not a conclusive diagnosis. Or they are used torule out other diagnoses or problems, rather than rul-ing in our leading suspected diagnosis. Thus, thediagnostic dilemma.
Many neurology diagnoses are still primarily a clini-cal diagnosis made from history and physical assess-ment, so it is important to understand what you areseeing. I start by breaking it down into two basic cat-egories: central nervous system (CNS) and peripher-al nervous system (PNS) findings.
The CNS comprises the brain and spinal cord; thePNS is everything else. Remember that the cranialnerves are considered part of the PNS but integrateinto the CNS by associated nucleuses. Thus, cranialnerves can sometimes give a confusing picture andneed to be taken in context with the clinical picture.
Spasticity, increased tone, hyperreflexia, andextensor plantar responses tend to support a CNSprocess. Hypotonia, flaccidity, or diminished reflexesare associated with PNS disorders.
Sensory dysesthesias or motor weakness of theCNS is more likely to be hemidysesthetic or hemi-
Locate the
LesionDIAGNOSTIC TIPS
Barbara Bishop
Major anatomical features of the human nervous system include the brain, thespinal cord, and each of the individual nerves. The brain and spinal cord make upthe central nervous system (CNS) and all the nerves and their branches make upthe peripheral nervous system (PNS). Nerves originating from the brain areclassified as cranial nerves, and nerves originating from the spinal cord are calledspinal nerves.Source: Thibodeau GA, Patton KT. Anatomy and physiology. 5th ed. St. Louis:Mosby;2003.p.343.
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JNP
June 2006410 The Journal for Nurse Practitioners - JNP
paretic. Sometimes it is limited to just an individuallimb. PNS sensory distortion is usually much morefocal, as in a limited stocking-glove distribution or anentire limb. PNS motor weakness is usually distrib-uted over a nerve or nerve root distribution.
If I suspect a CNS problem, I try to break it downbetween the brain and the spinal cord. If it is morecortical, symptoms are generally contralateral to theside of the lesion in the brain. Spinal lesions oftenhave a dermatome level associated with them.Symptoms are often bilateral below this level if thelesion is in the spinal cord itself because it is sosmall. Unilateral symptoms can be seen as well.Usually with unilateral symptoms, the lesion is not inthe spinal cord itself but perhaps compressing thecord or an exiting nerve root (which would make it aPNS problem).
If I suspect a PNS problem, I try to break it downbetween nerve root and more distal findings. If it isnerve root, pain and dysesthesia usually follow aspecific distribution pattern, rather than being dif-fuse, and encompass the entire length of the nerve.Sciatica is a classic example. If motor is affected, itusually encompasses the entire nerve root distribu-tion or entire limb. If it is more distal, usually onlypart of the limb is affected, and pain is often morediffuse, as in diabetic neuropathy.
Neurology can be very intimidating because it isinferential. The information in this article is a startingpoint, presenting very general concepts.Undoubtedly, you will find confusing presentationsthat do not fit neatly into these categories.Understanding these limitations, you can at leaststart to compartmentalize your examination betweenthe CNS and the PNS. This begins to make the dif-ferential diagnosis much more approachable.
Bibliography
Bates B. A guide to physical examination and history taking. New York:Lippincott;1983.
Goldberg S. Clinical neuroanatomy made ridiculously simple. Miami:MedMaster Inc.;1983.
Patterson J. Neurological differential diagnosis. Philadelphia: Springer-Verlag; 1991.
1555-4155/06/$ see front matter© 2006 Elsevier Inc. All rights reserved.doi:10.1016/j.nurpra.2006.04.001
Barbara Bishop, MS, ANP-C, CNRN, MSCN, works atVirginia Beach Neurology in Virginia Beach, VA. She canbe reached at [email protected].
Further columns of medication safety willfocus on various attempts that have been triedto decrease medication error and what an indi-vidual provider can do.
References
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14. Kohn LT, Corrigan JM, Donaldson M, editors. To err is human:building a safer health system. Committee on Quality of HealthCare in America, Institute of Medicine. Washington, DC: NationalAcademy Press: 1999.
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1555-4155/06/$ see front matter© 2006 Elsevier Inc. All rights reserved.doi:10.1016/j.nurpra.2006.04.006
Prescription PadContinued from Page 405
Maren Mayhew, MS, ANP, GNP, is the author and editorof Pharmacology for Primary Care Providers, a textbookfor NPs published by Mosby. She can be reached [email protected]. This is a monthly columnon medication news and controversies. Suggestions fortopics are welcome.
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