3.1 Sensory Loss Flashcards
General schema of the sensory pathways
Receptor -> peripheral nerve -> spinal root -> sensory tract -> thalamus -> sensory cortex
Merkel’s disk and free nerve fibers are examples of ______ receptors
Non-encapsulated
Represent the surface innervation of the sensory nerve roots
Dermatomes
Dermatome: T6
Xiphoid process
Dermatome: C6
Thumb
Dermatome: L4
Knee, big toe
Dermatome: genitalia
S2 - S3
General sensory modalities include:
Pain Light touch Temperature Vibration Position sense Deep pressure
Sensory changes due to interruption of ______: vary depending on whether the nerve involved is predominantly muscular, cutaneous or mixed. Deep pain and perception is intact.
Single peripheral nerve
Sensory changes due to interruption of _______: sensory impairment is bilaterally symmetrical. The longest and largest fibers are most affected, glove and stocking distribution of sensory loss
Multiple nerves (polyneuropathy)
Sensory changes due to interruption of _______: follows dermatomal distribution, intensified by movement of the spine and radiate in proximal distal fashion ( shooting or lancinating pain)
Nerve roots/ radiculopathy
Sensory changes due to interruption of _______: widespread dse may produce the same sensory defects as of the posterior nerve roots, proximal areas of the body also show pronounced sensory loss
Sensory ganglia/ neuronopathy/ ganglionopathy
Paraneoplastic, connective tissue dses ( sjogren syndrome), toxic exposure and idiopathic inflammation are examples of what type of sensory change:
Sensory changes due to involvement of sensory ganglia
All forms of sensation below a level that corresponds to that lesion
Complete spinal sensory syndrome
Affectation of the pain and thermal sensation on the side contralateral to the lesion, ipsilateral proprioceptive affectation, associated spastic motor paralysis on the ipsilateral side
Hemisection/ brown sequard syndrome
Abolition of pain and temperature on one or both sides over several segments but with sparing of tactile sensation
Syringomyelic syndrome
Vibration and position senses are most affected. Paresthesias may be common complaints, seen in MS, tabes dorsalis and HIV patients
Posterior dorsal column syndrome
Loss of pain and temperature sensation below the level of the lesion but relative or absolute sparing of proprioceptive sensation, spastic paralysis is a prominent feature
Anterior myelopathy/ anterior spinal artery syndrome
Examination sometimes include overtly hysterical findings like ipsilateral reduced hearing, smell and taste
Sensory loss due to suggestability and hysteria
Disturbance of discriminative sensory function without impairment of the primary modalities of sensation
Sensory inattention, extinction and neglect
Sensory loss due to lesions of the parietal lobe
Loss or diminution of all forms of sensation on the opposite side of the body
Spontaneous pain discomfort may appear on the affected side of the body (thalamic pain)
Hemisensory loss d/t a lesion of the thalamus / syndrome of dejerine-roussy
May cause crossed sensory disturbance
Medullary lesions
Crossed trigeminothalamic and lateral spinothalamic tracts run together; lesions at this level may cause loss of pain and temp on the opposite half of the face and body
Upper medulla, pons and midbrain lesion
Increase in sensibility to pain, pain in response to a stimulus not normally painful
Allodynia, hyperalgesia, hyperpathia
Abnormal spontaneous sensations experienced in the absence of stimulation
Paresthesia
Vibration sense
Pallesthesia
Unpleasant or painful sensation, either spontaneous or after a normally non painful stimulus
Dysesthesias
