Localization of Lesions PDF Imprimir E-mail

by R.M. Clemmons, DVM, PhD
Associate Professor of Neurology & Neurosurgery

One of the important aspects of evaluating any neurologic patient is to determine the location of the lesion. Luckily, the function of the nervous system is intimately tied to its structure. As such, when a function is lost, the structure involved is uncovered. Signs of neurologic disease can be divided into those representing diseases above the foramen magnum (head signs) and those below the foramen magnum (spinal cord signs). Head signs include seizures, head tilt, cranial nerve deficits, whole body and head tremors, and ataxia. Spinal cord signs include quadriparesis and paraparesis. The peripheral nervous system shows signs consistent with the distribution of the nerve involved. (See Table 1) Once the disease process is localized, the differential diagnosis can be made and the diagnostic approach determined.

Table 1. Neurologic Signs and Lesion Location.

 

Neurologic Sign

Location of Lesion

 

Change in Behavior or Personality

Cerebral Cortex, Thalamus, Hypothalamus

 

Seizures

Cerebral Cortex, Thalamus, Hypothalamus

 

Visual Dysfunction

Retina, Optic nerve, Visual pathways, Cerebral Cortex

 

Signs of Cranial Nerve Dysfunction

 

 

Anisocoria

Sympathetic or Parasympathetic innervation to the eye

 

Strabismus

CN III, CN IV, CN VI

 

Dropped jaw

CN V

 

Changed facial sensation

CN V

 

Paralysis of eyelid, lip or ear

CN VII

 

Dysphagia

CN IX, CN X

 

Megaesophagus

CN X

 

Laryngeal paralysis

CN X, CN XI

 

Paralysis of tongue

CN XII

 

Head tilt, circling, nystagmus

CN VIII (vestibular system)

 

Deafness

CN VIII (auditory system)

 

Incoordination of the Head and Body

Cerebellum

 

Paraparesis or Paraplegia

TL Spinal Cord

 

Paralysis of one Limb

Peripheral nerve

 

Flaccid Anus, Tail and Bladder

Cauda Equina

 
 
 
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