III./9. Disorders of the Peripheral Nervous System
Zsuzsanna Arányi
Introduction
Peripheral nervous system disorders are extremely common conditions, encountered not only by neurologists, but also by orthopedic surgeons, general surgeons, rheumatologists, and internists.
The peripheral nervous system includes all nervous structures outside the pia mater of the spinal cord and the brainstem. The olfactory nerve and the optic nerve are two exceptions, which are considered as extensions of the central nervous system. Accordingly, the peripheral nervous system includes the 3rd-12th cranial nerves, spinal roots, brachial and lumbosacral plexus, and the peripheral nerves. The cell bodies of the motor fibers of peripheral nerves are in a special
situation, as they are located within the brainstem and the spinal cord.
Therefore, they may be damaged in central nervous system disorders (e.g. intramedullary lesions, degenerative diseases), but cause ʽperipheral’ symptoms.
Under the heading of peripheral nervous system disorders, traditionally disorders of individual peripheral nerves
(mononeuropathies), plexopathies, and the systemic diseases of the peripheral nervous system (polyneuropathies) are discussed. Disorders of individual spinal roots (radiculopathies) are mentioned together with disorders of the spine.
Content
Based on the above, peripheral nervous system disorders are grouped into the following categories – learning units:
III./9.1. General structure of peripheral nerves; pathological forms of peripheral nerve damage and regeneration
III./9.2. General symptoms of peripheral nervous system disorders
III./9.3. General diagnosis of peripheral nervous system disorders
III./9.4. Mononeuropathies – tunnel syndromes III./9.5. Plexopathies
III./9.6. Polyneuropathies III./9.7. Summary
III./9.8. Test questions
The aim of this chapter on peripheral nervous system disorders is to teach students diseases of the peripheral nervous system commonly encountered in clinical practice.
This unit is only complementary to textbooks, and it strives mainly to call attention in a concise and didactic form to conditions that may be encountered by general practitioners.
A symptomatic approach is stressed, as the physician always meets the complaint or symptom first, which serves as a basis for diagnosis (including localization and etiology) and then for prognosis and therapy. Prognosis has a special significance in peripheral nervous system disorders, because nerve damage is often followed by spontaneous regeneration, which cannot be influenced. Providing the patient with correct information concerning the expected duration and extent of spontaneous recovery will spare him/her from seeking various “pseudo-interventions” in hope of recovery.
Before studying the disorders of the peripheral nervous system, a review of the anatomy of the peripheral nervous system is recommended. Most of the symptoms may be derived from the anatomical knowledge of the course and innervation territory of peripheral nerves. The first reading should be timed just prior to the lecture discussing this subject, and the second reading after the lecture.
For an adequate consolidation of knowledge, at least 2-3 readings are recommended. Finally, key words and phrases in italics should be read again.
Study time and assessment
The time needed for learning this chapter varies individually. In general, the first thorough reading requires 4-5 hours. It is advisable to leave some time in between repeated readings. This learning unit is closed by solving the test questions.
Literature
Ropper AH, Samuels MA. Adams & Victor's Principles Of Neurology, Ninth Edition, McGraw Hill, 2009
O'Brien M. Aids to the Examination of the Peripheral Nervous System, Fifth Edition, Saunders Elsevier, 2010 Baehr M, Frothscher M. Duus' Topical Diagnosis in
Neurology: Anatomy, Physiology, Signs, Symptoms. Thieme Flexibook, 2005
Stewart JD. Focal peripheral neuropathies, Fourth Edition, JBJ Publishing, 2010
Internet sites:
American Association of Neuromuscular and Electrodiagnostic Medicine: www.aanem.org
