Paralysis/paresis Normal to hyperreflexia Normal to incr muscle tone Minimal (disuse) muscle atrophy
LMN lesions lead to what signs?
Paralysis/paresis Hyporeflexia or areflexia Decr muscle tone Severe, rapid (neurogenic) muscle atrophy
Where are the UMNs and LMNs located?
UMN - cell bodies in brainstem and spinal cord LMN - cell bodies in brainstem (CrN) and ventral horn of spinal cord (peripheral nn)
What are the overall responsibilities of UMNs and LMNs?
UMN - initiation of voluntary movement and maintenance of tone in enxtensor mm for posture
LMN - innervate mm and glands of body, but also controlled by reflexes in spinal cord
What are the different types of sensory neurons and what do they do?
Segmental - synapse w/ LMNs to make reflex arc
Long tract - carry conscious proprioception and pain and touch to contralateral cerebral cortex
What are some abnormal reflexes and other signs of spinal injury?
Hyperreflexia Crossed-extensor reflex in lateral recumbency Mass reflex Spinal shock Schiff-Sherrington
Hyperreflexia can be caused by what?
Loss of UMN inhibition and also denervation hypersensitivity
What is mass reflex?
Dramatic hyperreflexia seen several months after spinal cord resection Consists of bilateral limb flexion, tail twitch, incontinence
What is spinal shock?
Spinal cord damage leading to transient areflexia in limbs caudal to lesion
Where are the lesions resulting in Schiff-Sherrington posture?
Damage to spinal segments T3-L3
What is the proper sequence of the neuro exam?
Observation of mental status, posture, and gait Palpation of muscular and skeletal system Evaluation of postural rxns Evaluation of cranial nerves Evaluation of spinal nerves & reflexes Evaluation of sensation
Abnormalities in mental status relate to lesions where?
Brainstem or thalamocortex
What are the different types of ataxia?
Sensory (conscious proprioception) - crossing-over of affected limbs and scuffing toes
Cerebellar (unconscious) - limbs positioned peripheral to center of gravity (wide-based gait)
Vestibular - circle, roll, fall, head tilt, nystagmus to affected side
What are the different tests for postural reactions?