gen med- paresis vs paralysis

what is the job of the motor system? what are its components?

allows us to support weight against gravity

composed of:

corticospinal pathway

rubrospinal pathway

reticulo and vestibulo-spinal pathways

what is the corticospinal pathway?

origin is in the cerebral cortex

responsible for fine motor movements

what is the rubrospinal pathway?

origin in the brainstem via the red nucleus

main motor pathway in non-humans/primates

what are the reticulo- and vestibulo-spinal pathways responsible for?

mediate extensor and flexor tone

what is the definition of paresis?

weakness with voluntary motor activity still intact

non-specific in terms of localization (forebrain, brainstem, spinal cord, neuromuscular systems)

what is the definition of paralysis?

complete loss of voluntary motor function

non-specific in terms of localization (forebrain, brainstem, spinal cord, neuromuscular systems)

what do lesions of upper motor neurons (UMN) result in?

lesions of the pyramidal tract (corticospinal) results in:

spasticity, hyper-reflexia, hypertonia, and positive babinksi sign

what do lesions of lower motor neurons (LMN) result in?

lesions of cell bodies of motor neurons (in cranial nerve motor nuclei or ventral horn of sponal cord) or their axons in nerves to the muscle (final common pathway) results in:

flaccidity, hypo-reflexia, hypotonia, atrophy

what do lesions in the forebrain result in?

contralateral hemiparesis/plegia or quadriparesis/plegia

contralateral cranial nerve deficits (UMN)

what do lesions in the brainstem result in?

ipsilateral hemiparesis, hemiplegia, or quadriparesis/plegia

ipsilateral complete cranial nerve deficits (LMN) of cranial nerves III-XII

what are the thoracic/pelvic limb deficits of lesions to the C1-C5 spinal cord?

thoracic limb deficit: UMN

pelvic limb deficit: UMN

what are the thoracic/pelvic limb deficits of lesions to the C6-T2 spinal cord?

thoracic limb deficit: LMN

pelvic limb deficit: UMN

what are the thoracic/pelvic limb deficits of lesions to the T3-L3 spinal cord?

thoracic limb deficit: normal

pelvic limb deficit: UMN

what are the thoracic/pelvic limb deficits of lesions to the L4-S3 spinal cord?

thoracic limb deficit: normal

pelvic limb deficit: LMN

what deficits occur with lesions of the S1-Cy spinal cord?

normal limbs

LMN anus, bladder, and tail

what clinical signs/positive tests are seen with C1-C5 myelopathies?

+/- tetraparesis/plegia (severe cases)

hyperpathia (pain)

CP deficits ipsilateral fore/hind

+/- ipsilateral hemiparesis/plagia

UMN fore/hind limb reflexes

normal withdrawal reflexes all 4 limbs

+/- intact pain perception (severe cases)

abnormal head carriage

root signature

myelopathy to which spinal cord segments can result in diaphragmatic paralysis?

C4, C5, C6 due to phrenic nerve involvement

what is root signature?

lameness associated with nerve root impingement

what clinical signs/positive tests are seen with C6-T2 myelopathies?

ipsilateral hemiparesis/plegia (if severe)

ipsilateral CP deficits fore/hind

LMN signs (hyporeflexia) fore limbs

UMN (hyperreflexia) hind limbs

abnormal head carriage +/- cervical pain

+/- loss of conscious pain perception

what can lesions to the T1-T3 spinal cord result in?

horner's syndrome

what is caudal cervical spondylomyelopathy?

breed predilection for large/giant breed dogs

affects hindlimbs more than forelimbs

progressive improvement over time

do serial neurologic examinations

what clinical signs/positive tests are seen with T3-L3 myelopathies?

ipsilateral or bilateral paraparesis/plegia

CP deficits of one or both hindlimbs

UMN reflexes hind, normal forelimbs

--> +/- UMN tone forelimbs if T13-L2 lesion is severe (border cells- cells inhibitory to hyper-reflexion)

spinal hyperpathia (thoracolumbar area or referred)

+/- panniculus loss

+/- loss of conscious pain perception hind limbs

evaluate gait/presence of ataxia (if ataxic, what type)

what clinical signs/positive tests are seen with L4-S2 myelopathies?

-ipsilateral or bilateral paraparesis/plegia

-normal forelimb myotatic reflexes, strength

-hind limb LMN reflexes and diminished withdrawal reflexes unilateral or bilateral (L4-L6 vs L7-S2)

-CP deficits unilateral or bilateral hind limbs

-urinary/fecal incontinence

-decreased anal tone, perineal reflex

-change in tail carriage

-lumbosacral hyperpathia on palpation +/- pelvic exam

what are 4 types of neuromuscular diseases?

nerve root (radiculopathy)

peripheral nerve (neuropathy; mono or poly)

neuromuscular junction (junctionopathy)

muscle (myopathy)

what are clinical signs of nerve root disease (radiculopathy)?

spinal hyperpathia/hyperesthesia

root signature

generalized weakness/paralysis

voice change

LMN signs to one/multiple limbs dependent on cause

normal mentation

muscle atrophy- focal or generalized

+/- sensory loss

+/- horner's syndrome

what are examples of radiculopathies?

polyradiculoneuritis

brachial plexus avulsion

what are clinical signs of motor neuropathies?

-flaccid paralysis or paresis of innervated structures (limb, facial muscles, esophagus, anus)

-neurogenic muscle atrophy

-reduced or absent reflexes and muscle tone

-muscle fasciculation/voice change

what are potential causes of motor neuropathies?

trauma, metabolic changes

what are clinical signs of sensory neuropathies?

-decreased pain response or sensation

-proprioceptive deficits

-abnormal sensation or sensitivity (paresthesia) of face, trunk or limbs

-self-mutilation

-reduced or absent reflexes without muscle atrophy

what are clinical signs of autonomic (+/- sensorimotor) neuropathies?

-anisocoria or dilated pupils

-decreased tear secretion

-decreased salivation

-bradycardia

what type of neuropathy is dysautonomia?

autonomic neuropathy

what are clinical signs of junctionopathies?

-normal mentation

+/- palpebral/menace deficits

-generalized motor weakness or paralysis dependent on cuase

-episodic or continual

-normal or hyporeflexic myotatic and withdrawal reflexes

+/- voice change

+/- muscle atrophy

what are examples of junctionopathies?

myasthenia gravis

tick paralysis

botulism

what are clinical signs of myasthenia gravis? what can be given to resolve junctionopathy?

exercise intolerance, diminished palpebral responses

patient responds when given tensilon (an acetylcholinesterase inhibitor)

what are clinical signs of myopathies?

generalized weakness

exercise intolerance

stiff, stilted gait

localized or generalized muscle atrophy

dimple contracture

muscle pain on palpation

limited joint movement (ie contracture)

+/- voice change (if severe)

+/- trismus (inability to open mouth)

what are examples of myopathies?

labrador myopathy

masticatory myositis

polymyositis

neospora or toxoplasma myositis