View source for Neurological Examination of Horses Overview

===Aims of Neurological Examination===

* There are two main aims of neurological examination:
*# To aid determination of the presence or absence of neurological disease.
*# To localise the lesion(s) when neurological disease is suspected.

===Indications for Neurological Examination===

* Neurological testing may be indicated by:
*# '''History'''
*#* For example, the owner reports a seizure-like episode. 
*# '''Clinical examination'''
*#* For example, an unexplained area of muscle atrophy or patchy sweating. 
*# '''Information from other tests'''
*#* Particularly negative, confusing or corroborating evidence from these.
*#* For example:
*#** A horse evaluated for pelvic limb lameness that may in fact have a neurological problem.
*#** A horse with altered mentation or depression that has already been found to have abnormal hepatic function.

===Approaches to Neurological Examination===

* A methodical approach is necessary, whatever the background, to ensure no aspect of examination is omitted.
* Two different approaches may be taken: 
*# '''Systems based'''
*#* The different neurological modalities of the systems are examined in turn.
*# '''Anatomic'''
*#* Tests are performed in turn working from head to tail. 
* A combination of the two approaches tends to be used in practice.

==Neuroanatomy==

* Certain basic facts must be understood before a decent neurological examination may be performed.

===White and Grey Matter===

* '''White matter''' consists of myelinated axons of nerve cells.
* '''Grey matter''' is made up of neuronal cell bodies, containing the nucleus.

===Afferent and Efferent===

* '''Afferent''' pathways relay sensory information from receptors towards the spinal cord or brain.
** For example:
*** Touch
*** Muscle stretch
*** Vision
*** Balance 
* '''Efferent''' pathways relay motor or effector information from the brain or spinal cord to muscles or organs.

===Motor Neurons and Motor Reflexes===

* '''Lower motor neurons''' are the last link in the efferent pathway.
** Directly innervate skeletal muscles.
** Cell bodies are located in the ventral horn of the grey matter of the spinal cord.
** Their axons run in peripheral nerves and synapse at the neuromuscular junction.
* '''Upper motor neurons''' communicate with lower motor neurons.
** They:
*** Relay information to lower motor neurons
*** Control the output of lower motor neurons.
** Upper motor neurons are found in the brain and spinal cord.
* The term '''reflex''' describes a certain sort of nervous pathway.
** The sequence of events in a reflex is as follows:
**#  Signals are derived from receptors.
**#* For example, tendon stretch.
**# Signals are conveyed directly in sensory (afferent) fibres.
**#  Afferent signals reach the central nervous system.
**#  Effector signals are generated in the CNS.
**#* This generally occues via an intermediate neuron, known as the internuncial neuron. 
**# Effector signals are relayed in the lower motor neurons to the muscles. 
** A reflex does NOT require:
*** Conscious perception of the stimulus
*** Ascending or descending upper motor neuron pathways
*** Ascending or descending proprioceptive pathways


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