Intractable postherpetic itch and cutaneous deafferentation after facial shingles

Abstract

Some patients develop chronic itch from neurological injuries, and shingles may be a common cause. Neuropathic itch can lead to self-injury from scratching desensate skin. A 39-year-old woman experienced severe postherpetic itch, but no postherpetic neuralgia, after ophthalmic zoster. Within 1 year, she had painlessly scratched through her frontal skull into her brain. Sensory testing and skin biopsies were performed on itchy and normal scalp to generate preliminary hypotheses about mechanisms of neuropathic itch. Quantitation of epidermal neurites in PGP9.5-immunolabeled skin biopsies demonstrated loss of 96% of epidermal innervation in the itchy area. Quantitative sensory testing indicated severe damage to most sensory modalities except itch. These data indicate that in this patient, severe postherpetic itch was associated with loss of peripheral sensory neurons. Possible mechanisms include electrical hyperactivity of hypo-afferented central itch-specific neurons, selective preservation of peripheral itch-fibers from neighboring unaffected dermatomes, and/or imbalance between excitation and inhibition of second-order sensory neurons.

Pruritus, pain, and small nerve fiber function in keloids: A controlled study

“…This type of itch, which coincides with pain, has been reported in neuropathic itch, such as in postherpetic neuralgia. 10 Several hypothetic mechanisms may explain this phenomenon. One mechanism could be related to mechanical damage of nociceptive primary afferent neurons by the deposition of collagen fibers, which evokes a central neuronal inhibitory process that prevents the itch at the center of the keloid, whereas the uninhibited regenerating C fibers at the keloid periphery exert their itch sensation.…”

The Itch-Producing Agents Histamine and Cowhage Activate Separate Populations of Primate Spinothalamic Tract Neurons

“…Itch and scratching perform an important function in protecting the skin from common threats, but itch can become intolerable and lead to vicious itch-scratch cycles and self injury (Keele and Armstrong, 1964;Wahlgren, 1999;Oaklander et al, 2002). Pruritus often accompanies skin and systemic diseases, and can be a symptom of neuropathy (Yosipovitch et al, 2003;Ikoma et al, 2006).…”

An Unusual Presenting Symptom in an Atypical Case of Acute Inflammatory Polyradiculopathy: Facial Pruritus

“…Neuropathic itch may originate from any lesion along this pathway. Peripheral causes for neuropathic itch are cervical/lumbar radiculopathy due to tumor, disc pathologies, postherpetic neuralgia, polyneuropathy (5)(6)(7)(8) and central causes are Creutzfeldt-Jakob disease, multiple sclerosis and neuromyelitis optica (9-11).…”