Sensory system

Spino-thalamic tract

Posterior tract

Dermatomos

SENSORY EXAMINATION LIGHT TOUCH PAIN TEMPERATURE VIBRATION PROPERIOCEPTION CORTICAL-2 point discrimination,streognosis,graphesthesia

Traps Light touch is represented in both the ST and DCML system so it is OK for sensory screening but not specific for either system. The sensory exam is perhaps the most subjective of the entire neurological exam so patient response can be difficult to interpret or at times be misleading.

SENSORY LOCALIZATION MONONEUROPATHY POLYNEUROPATHY ROOT SPINE BRAINSTEM THALAMUS CORTEX

Mononeuropathy

Mononeuropathy

Causes of painful sensory polyneuropathy DM HIV Amyloidosis Paraneoplastic neuropathy Alcohol neuropathy Vasculitis Fabry etc.

Pearls A sensory level is valuable in determining if there is spinal cord disease. Pain (sharp) is used to determine a sensory level. The sensory level on examination is usually 1-2 spinal cord segments below the actual spinal cord lesion. A sensory deficit from a spinal nerve lesion will be in a dermatome distribution. A sensory deficit from a peripheral nerve lesion will be in the distribution of that peripheral nerve. A sensory deficit from a polyneuropathy will have a stocking and glove distribution because the longest axons are the most affected. i  

Trigeminal-sensory rtact

Trigeminal –sensory functions

Trigmino-thlamic -tract VTTT-decussating to VPM DTTT-with no decussating to VPM

REVIEW QUESTIONS

A 60-year-old man has decreased sensation to pin prick over the left cheek but the forehead and jaw area are normal. This finding is most consistent with a sensory loss of which one of the following?

A. Left ophthalmic division of the 5th cranial nerve. B. Left mandibular division of the 5th cranial nerve. C. Left maxillary division of the 5th cranial nerve. D. Left descending tract of the 5th cranial nerve.

A 42-year-old man complains of burning sensation of both lower legs and both hands. The best explanation for his complaint is which one of the following?

A. He has a disease affecting axons of his peripheral nerves. B. He has a spinal cord lesion at the cervical level. C. He has a disease affecting the thalamus bilaterally. D. He has a disease affecting the somatosensory cortex of both parietal lobes

The patient has difficulty identifying numbers written on the palm of his left hand. Which one of the following answers best explains this finding?

A. A lesion of the left spinothalamic tract. B. A lesion of the right parietal lobe. C. A lesion of the right dorsal column. D. A lesion of the left medial pons.

A 55-year-old patient can stand with his eyes open but becomes unsteady with his eyes closed. Which one of the following answers is the best explanation for this finding?

A. A lesion of the dorsal columns. B. A lesion of the spinothalamic tracts. C. A lesion of the midline of the cerebellum. D. A lesion of the vestibular system.

Motor system

UMN Spasticity Hyperreflexia Plantar response

LMN Atrophy Hyporeflexia Fasciculations Flexor planter response