title: Differential myelinated and unmyelinated sensory and autonomic skin nerve fiber involvement in patients with ophthalmic postherpetic neuralgia.
abstract: Postherpetic neuralgia (PHN) is a common and exceptionally drug-resistant neuropathic pain condition. In this cross-sectional skin biopsy study, seeking information on the responsible pathophysiological mechanisms we assessed how ophthalmic PHN affects sensory and autonomic skin innervation. We took 2-mm supraorbital punch skin biopsies from the affected and unaffected sides in 10 patients with ophthalmic PHN. Using indirect immunofluorescence and a large panel of antibodies including protein gene product (PGP) 9.5 we quantified epidermal unmyelinated, dermal myelinated and autonomic nerve fibers. Although skin biopsy showed reduced epidermal and dermal myelinated fiber density in specimens from the affected side, the epidermal/dermal myelinated nerve fiber ratio was lower in the affected than in the unaffected side (p < 0.001), thus suggesting a predominant epidermal unmyelinated nerve fiber loss. Conversely, autonomic skin innervation was spared. Our study showing that ophthalmic PHN predominantly affects unmyelinated nerve fiber and spares autonomic nerve fiber might help to understand the pathophysiological mechanisms underlying this difficult-to-treat condition.
authors: Department of Neurology and Psychiatry, Sapienza University of Rome Rome, Italy.
authors: Andrea
authors: A
authors: Truini
authors: Department of Neurosurgery, Helsinki University Central Hospital Helsinki, Finland.
authors: Maija
authors: M
authors: Haanpaa
authors: Neurology Division "Salvatore Maugeri" Foundation-Institute of Telese Terme (BN) Italy Telese Terme, Italy.
authors: Vincenzo
authors: V
authors: Provitera
authors: Department of Neurology and Psychiatry, Sapienza University of Rome Rome, Italy.
authors: Antonella
authors: A
authors: Biasiotta
authors: Neurology Division "Salvatore Maugeri" Foundation-Institute of Telese Terme (BN) Italy Telese Terme, Italy.
authors: Annamaria
authors: A
authors: Stancanelli
authors: Neurology Division "Salvatore Maugeri" Foundation-Institute of Telese Terme (BN) Italy Telese Terme, Italy.
authors: Giuseppe
authors: G
authors: Caporaso
authors: Department of Neurosciences, Reproductive and Odontostomatological Sciences, University Federico II of Naples Naples, Italy.
authors: Lucio
authors: L
authors: Santoro
authors: Department of Neurology and Psychiatry, Sapienza University of Rome Rome, Italy.
authors: Giorgio
authors: G
authors: Cruccu
authors: Neurology Division "Salvatore Maugeri" Foundation-Institute of Telese Terme (BN) Italy Telese Terme, Italy.
authors: Maria
authors: M
authors: Nolano
keywords: intraepidermal nerve fiber; neuropathic pain; postherpetic neuralgia; skin biopsy; trigeminal nerve