Annals of neurology
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Annals of neurology · Jun 2005
Erythromelalgia: a hereditary pain syndrome enters the molecular era.
In contrast with acquired pain syndromes, molecular substrates for hereditary pain disorders have been poorly understood. Familial erythromelalgia (Weir Mitchell's disease), also known as primary erythermalgia, is an autosomal dominant disorder characterized by burning pain in the extremities in response to warm stimuli or moderate exercise. The cause of this disorder has been enigmatic, and treatment has been empirical and not very effective. ⋯ Erythromelalgia is the first human disorder in which it has been possible to associate an ion channel mutation with chronic neuropathic pain. Identification of mutations within a peripheral neuron-specific sodium channel suggests the possibility of rational therapies that target the affected channel. Moreover, because some other pain syndromes, including acquired disorders, involve altered sodium channel function, erythromelalgia may emerge as a model disease that holds more general lessons about the molecular neurobiology of chronic pain.
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The rare primary headache short-lasting unilateral neuralgiform headache attacks with conjunctival injection and tearing (SUNCT) is characterized by 3 to 200 attacks per day of severe unilateral orbital pain. Functional magnetic resonance imaging shows increased blood flow in the ipsilateral posterior inferior hypothalamus during attacks, indicating activation. We report the first patient with SUNCT in whom severe intractable pain (70 per day) was well controlled by electrode implant to and continuous stimulation of the posterior inferior hypothalamus. Ann Neurol 2005;57:925-927.
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Annals of neurology · Jun 2005
Gene transfer of glutamic acid decarboxylase reduces neuropathic pain.
We tested whether transfer of the gene coding for glutamic acid decarboxylase to dorsal root ganglion using a herpes simplex virus vector to achieve release of GABA in dorsal horn would attenuate nociception in this condition. Subcutaneous inoculation of a replication-defective herpes simplex virus vector expressing glutamic acid decarboxylase (vector QHGAD67) 7 days after selective L5 spinal nerve ligation reversed mechanical allodynia and thermal hyperalgesia; the antiallodynic effect lasted 6 weeks and was reestablished by reinoculation. QHGAD67 inoculation also suppressed induction of c-Fos and phosphorylated extracellular signal-regulated kinase 1 and 2 in the spinal cord.