Clinical Application of the Somatosensory System

Somatosensory System

System responsible for processing sensory information related to touch, pain, temperature, and proprioception.

Neuropathy

Dysfunction or pathology of one or more peripheral nerves.

Complete Transection

Total nerve cut resulting in complete loss of sensation and function below the injury.

Compression

Pressure on a nerve causing temporary sensory loss, recoverable upon pressure relief.

Paresthesias

Abnormal skin sensations such as burning, tickling, or "pins and needles" without a known physical cause.

Demyelination

Damage to the myelin sheath, slowing or stopping nerve conduction, leading to neuropathies.

Brown-Séquard Syndrome

Hemisection of the spinal cord leading to ipsilateral weakness and proprioceptive loss, with contralateral pain and temperature loss.

Posterior Column Lesion

Results in loss of proprioception, vibration, and coordination below the lesion.

Anterior Cord Lesion

Causes loss of pain, temperature, and motor function while sparing proprioception and discriminative sensation.

Central Cord Syndrome

Affects upper extremity function more than lower extremities; involves loss of nociceptive and temperature sensation.

Cauda Equina Syndrome

Damage to lumbar and sacral roots causing sensory loss, flaccid paresis, and bowel/bladder dysfunction.

Tethered Cord Syndrome

A spinal cord condition where it is tethered to the vertebrae, causing mobility impairment and pain.

Thalamic Lesions

Cause contralateral sensation loss affecting various discriminative sensory functions.

Somatosensory Cortex Lesions

Lead to impaired stereognosis, proprioception, and fast pain perception.

Fast Pain

Sharp, well-localized pain with minimal emotional component.

Slow Pain

Dull, aching pain associated with suffering and not well localized.

Visceral Pain

Cramping, burning pain that is not well localized and involves A delta & C fibers.

Pain Defined (IASP)

"An unpleasant sensory & emotional experience associated with actual or potential tissue damage or described in terms of such damage."

Normal Dorsal Horn Activity

AB fibers for touch, Ag/C fibers for nociceptive pain, with normal physiologic responses.

Sensitized Dorsal Horn

AB fibers cause allodynia, Ag/C fibers have excessive responses due to increased receptor activity.

Reorganized Dorsal Horn

Structural changes leading to persistent increased pain sensitivity.

Antinociceptive Systems

Systems that suppress pain perception via intrinsic and external mechanisms.

Intrinsic Antinociception

Involves Periaqueductal Gray (PAG), Locus Coeruleus, and Raphe Nuclei.

Narcotic-Induced Antinociception

Opiate drugs bind to endorphin receptors to reduce pain perception.

Stress-Induced Antinociception

Activation of raphespinal tracts and hormonal endorphin release for pain suppression.

Biological Amplification of Pain

Pain signals increase due to nerve irritation, endogenous chemicals, or emotional state.

Acute Pain

A warning system that assists in diagnosis, should be proactively managed with medication and non-drug therapies.

Chronic Pain

Persistent pain with no useful function; often leading to disability.

Nociceptive Pain

Properly functioning nociceptors fire due to tissue damage, such as in arthritis and cancer.

Neuropathic Pain

Pathological pain due to neural dysfunction, seen in conditions like diabetes and fibromyalgia.

Cognitive-Behavioral Interventions

Non-drug therapies including relaxation, distraction, and biofeedback to manage pain.

Physical Agents for Pain

Techniques like heat, cold, TENS, acupuncture, and massage for pain relief.

Peripheral Nerve Blocks

Injection of anesthetic to block nerve pain.

Surgical Pain Treatments

Includes dorsal rhizotomy, cordotomy, and deep brain stimulation.

Somatosensory System Evaluation

Uses quick screenings, neurodiagnostic tests, and nerve conduction studies.

Pain Rating Scales

Objective methods to measure subjective pain, including numeric intensity, visual analog, and verbal descriptor scales.