Neuropathic Pain and Neuralgias Vocabulary

Vocabulary flashcards covering the etiology, pathogenesis, clinical manifestations, and treatments of postherpetic neuralgia, neuropathic pain, trigeminal neuralgia, phantom limb pain, and complex regional pain syndrome (CRPS).

Herpes Zoster Pathogenesis

The pathological process where virus travels to dermatomes from affected sensory ganglia and peripheral nerves, causing vesicular eruption and hyperpathia; damage to and loss of large nerve fibers leads to postherpetic neuralgia pain.

Postherpetic Neuralgia Clinical Manifestations

Characterized by constant pain (burning, aching, throbbing), intermittent pain (stabbing, shooting), and stimulus-evoked pain such as allodynia.

Postherpetic Neuralgia Treatments

Management including early antivirals (Acyclovir to inhibit herpes DNA replication, Valacyclovir), topical analgesics ($5\%$ Lido gel, Lido-prilocaine cream), tricyclic antidepressants (Amitriptyline or desipramine), and regional nerve blocks.

Neuropathic Pain Etiology

A neurologic system pain problem resulting from peripheral nerve involvement, nerve entrapment, nerve compression from a tumor mass, or various neuralgias (trigeminal, postherpetic, posttraumatic).

Neuropathic Pain Pathogenesis

Involves neural degeneration, neuroma formation causing abnormal generation of spontaneous neural discharges from the injured sensory neuron, and changes in central nervous system (CNS) function.

Allodynia

Pain produced by a nonnoxious stimulus.

Neuropathic Pain Treatments

Interventions including electrical stimulation of peripheral nerve or spine, restoring or preventing nerve damage, and pharmacologic therapy (local anesthetic, $\alpha_2$ adrenergic agonist affecting nerve signaling, tricyclic antidepressants, and opioids).

Trigeminal Neuralgia Etiology and Pathogenesis

Condition caused by compression of the trigeminal nerve (classic, idiopathic, or secondary), leading to demyelination of the ganglion, root, and nerve, as well as neuronal voltage-gated ion channels mutation.

Trigeminal Neuralgia Clinical Manifestations

Presents with recurring, sudden onset of sharp, stabbing pain, and numbness.

Trigeminal Neuralgia Treatments

Management involving pharmacologic treatment with the antiepileptic Carbamazepine (Tegretol), surgical release of vessels or scar tissue around the semilunar ganglion or root in the cranial fossa, and avoidance of cause and eye injury.

Phantom Limb Pain Etiology and Pathogenesis

Pain originating after amputation of a limb as nerves attempt to regenerate and form neuromas, generating abnormal electrical signals.

Phantom Limb Pain Clinical Manifestations and Treatments

Manifests as burning, aching, and electric type pain; treated using Gabapentin, Lidocaine, TENS, and peripheral nerve stimulation.

Complex Regional Pain Syndrome (CRPS) Etiology

Pain syndrome triggered by injury to a nerve, classified as CRPS I (unknown nerve injury) or CRPS II (damage to peripheral nerves).

CRPS Pathogenesis

Pathology involving pain, inflammation, and sympathetic nervous system dysregulation, where increased central sympathetic activity leads to poor blood flow.

CRPS Clinical Manifestations

Features sensory, focal autonomic, and motor abnormalities, including burning, aching, trophic abnormalities, motor abnormalities, and decreased range of motion (ROM).

CRPS Treatments

Comprehensive therapy consisting of physical therapy (PT), desensitization, acupuncture, and medications (tricyclic antidepressants, antiepileptic agents, NSAIDs, bisphosphonates, and topical Lido & capsaicin).