Skip to Main Content


In this single chapter, an attempt is made to provide an overview of the very large and difficult subject of peripheral nerve disease. Because the structure and function of the peripheral nervous system are relatively simple, one might suppose that our knowledge of its diseases would be fairly complete. Such is not the case. For example, when a group of patients with chronic polyneuropathy were investigated intensively in a highly specialized center for the study of peripheral nerve diseases several decades ago, a suitable explanation for their condition could not be found in 24 percent (Dyck et al, 1981) and even more discouraging figures prevail in our clinics today. Moreover, the physiologic basis of many neuropathic symptoms continues to be elusive and in several of the neuropathies the pathologic changes have not been fully determined.


There has, however, been a surge of interest in diseases of the peripheral nervous system (PNS), which promises to change this state of affairs. Rapidly advancing techniques in the fields of immunology and molecular genetics are now clarifying entire categories of neuropathic disease. Also, in recent years, effective forms of treatment for several peripheral neuropathies have been introduced, making accurate diagnosis imperative. For these reasons, clinicians now find the peripheral neuropathies among the most challenging and gratifying categories of neurologic disease.


It is important to have a clear concept of the extent of the PNS and the mechanisms by which it is affected by disease. The PNS includes all neural structures lying outside the pial membrane of the spinal cord and brainstem with the exception of the optic nerves and olfactory bulbs, which are special extensions of the brain. The nerves within the spinal canal and attached to the ventral and dorsal surfaces of the cord are the spinal roots; those attached to the ventrolateral surface of the brainstem are the cranial nerve roots, or cranial nerves.


The dorsal, or posterior (afferent, or sensory), spinal roots consist of central axonal processes of the sensory and cranial ganglia. On reaching the spinal cord and brainstem, the roots extend for variable distances into the dorsal horns and posterior columns of the cord and into the spinal trigeminal and other tracts in the medulla and pons before synapsing with secondary sensory neurons, as described in Chaps. 8 and 9 that are devoted to the neurology of pain and sensation. The peripheral axons of the dorsal root ganglion cells are the sensory nerve fibers. They terminate as freely branching or specialized corpuscular endings—i.e., the sensory receptors—in the skin, joints, and other tissues. The sensory nerve fibers vary greatly in size and in the thickness of their myelin covering; based on these dimensions, they are classified as type A, B, or C, as discussed in Chap. 8.


The ventral, or anterior (efferent, or motor), roots are composed of the emerging axons of anterior and lateral horn cells and motor nuclei ...

Want remote access to your institution's subscription?

Sign in to your MyAccess profile while you are actively authenticated on this site via your institution (you will be able to verify this by looking at the top right corner of the screen - if you see your institution's name, you are authenticated). Once logged in to your MyAccess profile, you will be able to access your institution's subscription for 90 days from any location. You must be logged in while authenticated at least once every 90 days to maintain this remote access.


About MyAccess

If your institution subscribes to this resource, and you don't have a MyAccess profile, please contact your library's reference desk for information on how to gain access to this resource from off-campus.

Pop-up div Successfully Displayed

This div only appears when the trigger link is hovered over. Otherwise it is hidden from view.