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Involvement of the multidrug resistance transporters in cisplatin-induced neuropathy in rats. Comparison with the chronic constriction injury model and monoarthritic rats.

It has recently been suggested that P-glycoprotein is involved in the genesis and the treatment of the neurotoxic adverse events of anticancer drugs, including vincristine. A lower activity of P-glycoprotein in the peripheral nervous system (PNS) than in the central nervous system could contribute to the neurotoxicity of vincristine. Vincristine treatment is responsible for the induction of multidrug resistance (MDR) gene expression and transporter activity, with deleterious consequences, including a potential decrease in the efficiency of opioid analgesics, antidepressants or antiepileptics. Concerning cisplatin, which is also a strong neurotoxic drug but only an multidrug resistance protein 2 (MRP2) substrate, the same assumption could be suggested for MRP2 nervous function. The aim of this study was to assess MDR gene and protein activity in a rat model of cisplatin-induced neuropathy compared with different peripheral nerve injury models, i.e. mononeuropathy and inflammatory pain (monoarthritis). First, in cisplatin-induced neuropathy, this study demonstrated low MRP2 gene expression in dorsal root ganglia compared with the brain and spinal cord, which could contribute to the strong neurotoxicity of cisplatin in the PNS and particularly the dorsal root ganglia. Thus, gene expression increased in cisplatin-induced neuropathy but decreased in mononeuropathy and remained unchanged in monoarthritis models. Transporter activity of nervous tissues increased in the cisplatin-induced neuropathy, mononeuropathy and monoarthritis to different intensities (3.7-, 1.8- and 1.8-fold, respectively). The development of a MDR in the cisplatin-induced neuropathy is a striking difference with mononeuropathy and monoarthritis models, and characterizes the neuropathies induced by this anticancer drug.

ATP Binding Cassette Transporter, Subfamily B, Mem↗

The use of complementary and alternative medicines by patients with peripheral neuropathy.

Complementary and alternative medicine (CAM) therapies have become increasingly popular and are used regularly by patients with chronic neurological disorders. The prevalence and characteristics of CAM use by patients with peripheral neuropathy is unknown. We performed a prospective, questionnaire-based study to determine the prevalence and patterns of use of CAM therapies in 180 consecutive outpatients with peripheral neuropathy. The use of CAM was reported by 77 patients (43%) with neuropathy. The most frequent were megavitamins (35%), magnets (30%), acupuncture (30%), herbal remedies (22%), and chiropractic manipulation (21%); 37 (48%) tried more than one form of alternative treatment. Seventeen respondents (27%) thought their neuropathy symptoms improved with these approaches. Those who used CAM were slightly younger (mean age 62 vs. 65 years, p = 0.05) and more often college educated (39% vs. 24%, p = 0.03) compared to CAM nonusers. They also more often reported burning neuropathic pain (62% vs. 44%, p = 0.01). Patients with diabetic neuropathy used CAM more frequently than others (p = 0.03). The most common reason for using CAM was inadequate pain control (32%). Almost half of patients did not consult a physician before starting CAM. We conclude that there is a high prevalence of CAM use in our patients with neuropathy, and one-quarter reported that their symptoms improved. CAM users were better educated than nonusers, but most did not discuss CAM treatments with their physician. Neuropathic pain was substantially more common in CAM users, and lack of pain control was the most common reason for CAM use.

Acupuncture Therapy↗

Mitochondrial dysfunction as a cause of optic neuropathies.

Mitochondria are increasingly recognized as central players in the life and death of cells and especially of neurons. The energy-dependence of retinal ganglion cells (RGC) and their axons, which form the optic nerve, is singularly skewed. In fact, while mitochondria are very abundant in the initial, unmyelinated part of the axons anterior to the lamina cribrosa, their number suddenly decreases as the myelin sheath begins more posteriorly. The vascular system also presents different blood-brain barrier properties anterior and posterior to the lamina, possibly reflecting the different metabolic needs of the optic nerve head (unmyelinated) and of the retrobulbar optic nerve (myelinated). Mitochondrial biogenesis occurs within the cellular somata of RGC in the retina. It needs the coordinated interaction of nuclear and mitochondrial genomes. Mitochondria are then transported down the axons and distributed where they are needed. These locations are along the unmyelinated portion of the nerve, under the nodes of Ranvier in the retrobulbar nerve, and at the synaptic terminals. Efficient transportation of mitochondria depends on multiple factors, including their own energy production, the integrity of the cytoskeleton and its protein components (tubulin, etc.), and adequate myelination of the axons. Any dysfunction of these systems may be of pathological relevance for optic neuropathies with primary or secondary involvement of mitochondria. Leber's hereditary optic neuropathy (LHON) is the paradigm of mitochondrial optic neuropathies where a primary role for mitochondrial dysfunction is certified by maternal inheritance and association with specific mutations in the mitochondrial DNA (mtDNA). Clinical phenocopies of this pathology are represented by the wide array of optic neuropathies associated with vitamin depletion, toxic exposures, alcohol and tobacco abuse, and use of certain drugs. Moreover, the recent identification of mutations in the nuclear gene OPA1 as the causative factor in dominant optic atrophy (DOA, Kjer's type) brought the unexpected finding that this gene encodes for a mitochondrial protein, suggesting that DOA and LHON may be linked by similar pathogenesis. Polymorphisms in this very same gene may be associated with normal tension glaucoma (NTG), which might be considered a genetically determined optic neuropathy that again shows similarities with both LHON and DOA. Exciting new developments come from first examples of mitochondrial optic neuropathies in animal models that are genetically determined or are the result of ingenious engineering of mitochondrial gene expression, or from biochemical manipulations of the respiratory complexes. Even more exciting is the first successful attempt to correct the LHON-related complex I dysfunction by the allotopic nuclear expression of the recoded mitochondrial gene. There is hope that the genetic complexities, biochemical dysfunctions, and integrated anatomical-physiological cellular relationships will soon be precisely delineated and that promising therapeutic and prophylactic strategies will be proposed.

Animals↗

Leber hereditary optic neuropathy associated with antiretroviral therapy for human immunodeficiency virus infection.

PURPOSE: Antiretroviral therapy has reduced the morbidity and mortality associated with human immunodeficiency virus (HIV) infection. However, side effects are increasingly recognized, including a commonly reported toxic mitochondrial myopathy. We report such a case of Leber hereditary optic neuropathy in a patient with antiretroviral therapy for HIV infection and speculate on a possible toxic etiologic role in the development of Leber hereditary optic neuropathy by a shared mitochondrial mechanism. METHODS: Case Report. Bilateral optic disk abnormalities observed in a 38-year-old HIV positive man with a family history of Leber hereditary optic neuropathy were documented with fundus photography, color vision testing, and visual field testing. Mitochondrial DNA testing was used to confirm the genetic predisposition to Leber hereditary optic neuropathy. RESULTS: Progressive bilateral optic nerve pallor temporally associated with the administration of antiretroviral medication was observed. Diagnostic testing revealed progressive visual field and color vision loss as well as a mitochondrial DNA mutation consistent with Leber hereditary optic neuropathy. CONCLUSION: Antiretroviral therapy may be associated with the onset of Leber hereditary optic neuropathy in genetically predisposed patients.

Adult↗

Anti-sulfatide IgM antibodies in peripheral neuropathy.

Anti-sulfatide IgM antibodies have been recently associated with neuropathy but the clinical and electrophysiological correlations of this reactivity remains unclear. We reviewed the clinical and electrophysiological features of patients with high anti-sulfatide titers detected in our laboratory from 1991 to 1998. Of the 564 patients with different neurological diagnosis tested by enzyme-linked immunosorbent assay (ELISA), 11 had high anti-sulfatide IgM titers (>1/8000), 26 had titers of 1/8000 while 78 had titers of 1/4000. All patients with high anti-sulfatide IgM titers had a chronic, dysimmune, mostly sensorimotor neuropathy that in seven was associated with IgM monoclonal gammopathy. In most of these patients electrophysiological and morphological studies were consistent with a predominantly demyelinating neuropathy frequently associated with prominent axonal loss. Antibody titers of 1/8000, though always associated with neuropathy, did not correlate with a particular form or cause of neuropathy, while lower titers were equally distributed in patients with different neurological disorders. Our study indicate that high anti-sulfatide IgM titers (>1/8000) are highly predictive for a chronic, dysimmune, mostly demyelinating neuropathy often associated with IgM monoclonal gammopathy, and may therefore have potential diagnostic relevance.

Aged↗

Clinical correlate and fine specificity of anti-GQ1b antibodies in peripheral neuropathy.

We studied the frequency, fine specificity and clinical correlate of anti-GQ1b IgG and IgM antibodies in 216 patients with neuropathy including three with Miller Fisher syndrome (MFS), 73 with Guillain-Barré syndrome (GBS), 99 with neuropathy associated with IgM monoclonal gammopathy (PN+IgM) and 41 with other neuropathies, and compared the data with 92 disease or normal controls. We found high (>1/100) anti-GQ1b IgG titers in all three MFS patients and in two GBS patients (2.7%) with ophthalmoplegia and ataxia, while high anti-GQ1b IgM were only found in two patients with a chronic demyelinating sensorimotor neuropathy associated with IgMkappa monoclonal gammopathy (2%). By overlay HPTLC, IgG antibodies in MFS and GBS either selectively reacted with GQ1b or also bound to GD3, and less intensely to GD1b, while IgM antibodies from both patients with PN+IgM also strongly reacted with GD1b and, in one, with GD3 and GT1b. The constant association of anti-GQ1b antibodies with dysimmune neuropathies and the correlation between their isotype, fine specificity and clinical presentation, support a possible pathogenetic link between these antibodies and the neuropathy.

Antibody Formation↗

[Demyelinating neuropathy and Sjögren's syndrome: a diagnostic pitfall].

INTRODUCTION: Neuropathies induced by Sjögren's syndrome (SS) are usually axonal. Nevertheless some demyelinating neuropathies have been described in patients with SS. To date, the relationship between demyelinating neuropathies and SS remains imprecise. CASE REPORT: A 75 year-old man presented with a chronic history of sensory disturbances linked to demyelinating neuropathy. Electroneuromyography revealed a demyelinating neuropathy and complementary tests revealed both Sjögren's syndrome (SS) and HMSN IA. CONCLUSION: We suggested that an inherited affection might be researched before considering that demyelinating neuropathy might be a form of peripheral nervous system involvement in SS.

Aged↗

Aspergillus parasellar abscess mimicking radiation-induced neuropathy. Case report.

BACKGROUND: Transsphenoidal surgery is a safe procedure for treatment of pituitary adenomas. However, several complications, including post-surgical infection, are known. We describe a case of Aspergillus parasellar abscess that presented with cranial neuropathies following transsphenoidal surgery and radiosurgery. We initially diagnosed the case as radiation-induced neuropathies, which delayed the detection of Aspergillus. CASE DESCRIPTION: A 55-year-old man underwent transsphenoidal surgery for a pituitary adenoma that presented with pituitary apoplexy. Dexamethasone had been continuously administered for hypocortisolism probably caused by pituitary apoplexy. Four years later, radiosurgery was performed for a relapse in the right cavernous sinus. Another 4 years later, he developed painful right ophthalmoplegia, right ptosis, and bilateral visual impairment, successively. We initially suspected that the painful ophthalmoplegia and ptosis were because of radiation-induced cranial neuropathies; however, results of magnetic resonance (MR) imaging and his clinical course were not consistent with those of radiation-induced neuropathies. Therefore, we performed exploratory surgery that revealed a subdural abscess on the planum sphenoidale. Culture of a specimen grew Aspergillus fumigatus. CONCLUSION: Intracranial fungal abscess is a fatal complication unless it is treated early. It is thus important to consider the possibility of parasellar infection and differentiate it from radiation-induced cranial neuropathies when a patient presents with cranial neuropathies after transsphenoidal surgery and radiosurgery.

Abscess↗

Hypertrophic inflammatory neuropathy involving bilateral brachial plexus.

BACKGROUND: The present case is an example of hypertrophic inflammatory neuropathy (HIN). This entity is a rare tumor-like, chronic inflammatory, focal or multifocal, mainly demyelinating neuropathy of unknown origin, most frequently involving the brachial plexus. CASE DESCRIPTION: The authors describe a 67-year-old man presenting with a nodular mass in his right supraclavicular fossa. A nodular mass grossly resembling a schwannoma originating from a single nerve fascicle was surgically removed from the right C6 spinal nerve. Histologically, endoneurial edema, fibrosis, focal chronic inflammation, and extensive "onion bulb" formation were seen. Electron microscopy studies and immunohistochemistry proved that the onion bulb-forming cells were schwannian in nature and that the whorls of onion bulbs surrounded a generally demyelinated axon. Three months following surgery the patient developed acute painless paralysis of his right biceps brachii muscle that rapidly reversed; after that he remained neurologically asymptomatic. MRI revealed multiple fusiform mass lesions involving the brachial plexus bilaterally. Electrophysiologic studies demonstrated a bilateral, asymmetrical, mainly demyelinating neuropathy involving the brachial plexus; they failed to reveal any abnormality suggestive of generalized neuropathy. CONCLUSION: HIN is different from other focal tumor-like neuropathies and in particular from localized hypertrophic neuropathy (LHN).

Aged↗

Neuropathy, M components, and amyloid.

Of eighty-seven patients with nonhereditary systemic amyloidosis, ten had evidence of peripheral neuropathy. There was median-nerve neuropathy due to infiltration of the flexor retinaculum with amyloid in six patients. Two patients had diffuse sensorimotor neuropathy and two patients had sensory loss without evidence of motor impairment--three of these cases had amyloid deposition demonstrated by nerve biopsy. Neurological manifestations in all ten patients preceded other evidence of amyloidosis by 6 months-4 years (mean, 1 to 5 years). Neuropathy occurred in six of thirty-eight patients with primary amyloidosis and four of fourteen with amyloidosis associated with malignant B-cell dyscraias; and all patients with neuropathy had either a serum-M-component or Bence-Jones proteinuria. In contrast, neuropathy was not noted in any of the fifty-six patients in this series who had no evidence of a monoclonal gammopathy (thirty-five with secondary and twenty-one with primary amyloidosis).

Amyloidosis↗

Laser in situ keratomileusis-induced optic neuropathy.

OBJECTIVE: To report a case of bilateral optic neuropathy after bilateral laser-assisted in situ keratomileusis (LASIK) surgery. DESIGN: Observational case report. METHODS: Complete eye examination with detailed evaluation of the optic nerve, detailed medical history, stereo disc photographs, GDx Nerve Fiber Analyzer testing, Humphrey 24-2 SITA visual field testing, diurnal intraocular pressure measurement, serologic evaluation, and magnetic resonance imaging of the brain and orbits. MAIN OUTCOME MEASURES: Optic nerve status, visual field status, and visual acuity. RESULTS: A subject with previously healthy optic nerves had bilateral optic neuropathy develop after LASIK surgery. This neuropathy manifested with a subjective decrease in visual field, normal visual acuity, normal color vision, relative afferent pupillary defect, increased cupping of the optic nerve with focal neuroretinal rim defects, decreased nerve fiber layer thickness, and nerve fiber bundle-type visual field defects. The subject had no other risk factors for optic neuropathy. No other cause of neuropathy was identified. CONCLUSIONS: Optic neuropathy is a potential vision-threatening complication of LASIK surgery. This complication may be due to barotrauma or ischemia related to extreme elevation of intraocular pressure by the suction ring. Careful examination of the optic nerve before and after LASIK surgery is warranted.

Adult↗

Fundus lesions in malignant hypertension. V. Hypertensive optic neuropathy.

We produced experimental renovascular arterial hypertension in 57 rhesus monkeys by modified Goldblatt's procedures. Hypertensive fundus changes were studied in detail by serial ophthalmoscopy and fluorescein fundus angiography in all animals on a long-term follow-up, and pathologically in 23 eyes. Initial evidence of hypertensive optic neuropathy was optic disc edema which developed at the median blood pressure (BP) of 190 mmHg (normal BP, 120 mmHg). On follow-up, mild to marked pallor of the optic disc developed. The optic disc changes were correlated with BP and other fundus changes. Pathogenesis of hypertensive optic neuropathy, which has been highly controversial so far, is discussed at length in the light of the findings of the present study and other recent evidence. All the available clinical and pathologic findings in the present study indicate that hypertensive optic neuropathy represents a form of anterior ischemic optic neuropathy, and that hypertensive optic neuropathy is a distinct entity. A caution is given against a precipitous reduction of BP in patients with hypertensive optic neuropathy because that may cause complete, permanent blindness.

Animals↗

Dysthyroid optic neuropathy. The crowded orbital apex syndrome.

The authors have reviewed the clinical presentation, visual fields, color vision testing, visual-evoked potentials, and computed tomographic (CT) findings of 58 patients (95 eyes) with dysthyroid optic neuropathy. The authors compared these findings to a control group of 60 patients (119 eyes) with thyroid eye disease who underwent CT scanning and did not exhibit evidence of optic neuropathy. Clinically, dysthyroid optic neuropathy is an insidious disease; when compared with the usual Graves' orbitopathy patient, the optic neuropathy group presented at a later age and with a later onset of thyroid eye disease. The patients in this group were more likely to be male and/or diabetic, and often presented with desaturation of color vision. Asymmetrical extraocular muscle restriction and vertical tropias were more frequent in the optic neuropathy group. The most sensitive indicators of optic nerve dysfunction appeared to be visual-evoked potentials and color vision. Computed tomographic studies confirmed that apical orbital crowding was a characteristic feature of optic neuropathy. These findings should alert the clinician to a more aggressive approach to these patients.

Adult↗

Retinopathy and optic neuropathy in bone marrow transplantation for breast cancer.

PURPOSE: To characterize the ocular toxicity of a bone marrow transplant regimen does not include total body or focal head irradiation. METHODS: Nine patients with advanced breast cancer were referred for visual symptoms after high-dose chemotherapy with cisplatin, cyclophosphamide, and carmustine and autologous bone marrow transplantation without total body irradiation or local head irradiation. RESULTS: Symptoms consistent with optic neuropathy and retinopathy developed in five patients. Retinopathy alone developed in three patients and optic neuropathy alone developed in one. Retinal abnormalities included cotton-wool spots, intraretinal hemorrhages, and macular exudate. Optic nerve findings included disk swelling and subsequent pallor. Symptoms and signs associated with retinopathy were generally reversible, whereas those associated with optic neuropathy often were permanent. Retinopathy and/or optic neuropathy developed in all of the patients from 1 to 5 months after bone marrow transplantation. Resolution or stabilization of findings was observed 2-4 months after presentation. Two patients with optic neuropathy showed progression of field and acuity loss after 4 months. When compared with control subjects, the exposure of patients to cyclophosphamide and carmustine was no different. However, cisplatin exposure was 1.2-fold higher in patients with ocular toxicity compared with control subjects. CONCLUSION: Optic neuropathy and retinopathy are presumed to arise from the administration of a high-dose chemotherapy regimen. As techniques in supportive care improve, long-term adverse effects of these therapies now are becoming apparent.

Adult↗

Screening for auditory neuropathy in a school for hearing impaired children.

OBJECTIVE: Hearing loss in children may be due to a wide variety of pathologies. Recently, use of otoacoustic emission technology has led to identification of auditory neuropathy as a distinct hearing disorder. Children with auditory neuropathy require audiological and educational management that may differ from that required by other hearing impaired students. For this reason, screening for auditory neuropathy may be appropriate for children attending schools for the hearing impaired. The study investigated the utility of using otoacoustic emission measures for school screening of hearing impaired children. METHODS: In this study, 81 children aged 6-12 years who attended one school for the deaf were screened for indications of auditory neuropathy. Children found to have consistent otoacoustic emissions were given a full diagnostic audiological test battery. RESULTS: Two children had transient otoacoustic emission results indicating normal outer hair cell function in one or both ears. A follow-up diagnostic assessment for the two positive cases was strongly suggestive of auditory neuropathy. CONCLUSIONS: There is a need for routine auditory neuropathy screening at schools for hearing impaired children.

Auditory Perceptual Disorders↗

Optic nerve degeneration and mitochondrial dysfunction: genetic and acquired optic neuropathies.

Selective degeneration of the smallest fibers (papillo-macular bundle) of the human optic nerve occurs in a large number of optic neuropathies characterized primarily by loss of central vision. The pathophysiology that underlies this peculiar pattern of cell involvement probably reflects different forms of genetic and acquired mitochondrial dysfunction. Maternally inherited Leber's hereditary optic neuropathy (LHON), dominant optic atrophy (Kjer disease), the optic atrophy of Leigh's syndrome, Friedreich ataxia and a variety of other conditions are examples of inherited mitochondrial disorders with different etiologies. Tobacco-alcohol amblyopia (TAA), the Cuban epidemic of optic neuropathy (CEON) and other dietary (Vitamins B, folate deficiencies) optic neuropathies, as well as toxic optic neuropathies such as due to chloramphenicol, ethambutol, or more rarely to carbon monoxide, methanol and cyanide are probably all related forms of acquired mitochondrial dysfunction. Biochemical and cellular studies in LHON point to a partial defect of respiratory chain function that may generate either an ATP synthesis defect and/or a chronic increase of oxidative stress. Histopathological studies in LHON cases and a rat model mimicking CEON revealed a selective loss of retinal ganglion cells (RGCs) and the corresponding axons, particularly in the temporal-central part of the optic nerve. Anatomical peculiarities of optic nerve axons, such as the asymmetric pattern of myelination, may have functional implications on energy dependence and distribution of mitochondrial populations in the different sections of the nerve. Histological evidence suggests impaired axonal transport of mitochondria in LHON and in the CEON-like rat model, indicating a possible common pathophysiology for this category of optic neuropathies. Histological evidence of myelin pathology in LHON also suggests a role for oxidative stress, possibly affecting the oligodendrocytes of the optic nerves.

Animals↗

[Iatrogenic neuropathies].

During the last few years the list of drugs capable of inducing a iatrogenic neuropathy has been considerably lengthened. Drug toxicity to peripheral nerves may be discovered at the experimental stage, but it is usually recognized after the drug has been launched on the market, hence the importance of pharmacovigilance. The responsibility of a drug for the occurrence of neuropathy may be difficult to prove, particularly when the drug is used in the treatment of a disease which, by itself, may be responsible for a lesion of the peripheral nervous system. Iatrogenic neuropathies are usually axonal, but some drugs produce a primary disorder in the myelin-Schwann cell couple. Schwann cell diseases may be induced by drugs, such as perhexiline maleate, amiodarone or chloroquine, which inhibit lysosomal enzyme activity. In such cases inclusions representing fat-loaded lysosomes can be detected in various tissues, and particularly in Schwann cells. In certain patients, notably those treated with gold salts, an immune mechanism might be responsible for neuropathy. Most drug-induced neuropathies are due to a primary lesion of the neuron which is more often an axonopathy than a neuronopathy. It is usually a retrograde distal axonopathy the occurrence of which is attributed to a disorder of the fast retrograde axonal flow. In a few cases, the finding of a biochemical mechanism perturbing the axonal flow may help in preventing the occurrence of a iatrogenic neuropathy.

Amiodarone↗

Hereditary spastic paraplegia associated with peripheral neuropathy: a distinct clinical and genetic entity.

Hereditary motor and sensory neuropathy type V is a very rare disease in which hereditary spastic paraplegia is associated with peripheral motor and sensory neuropathy. The symptomatic onset of the disorder is usually in the second decade of life or later and the course is progressive over many years. Hereditary motor and sensory neuropathy type V is inherited as an autosomal dominant trait usually showing incomplete penetrance. So far, no molecular data are available in the literature about this disease. In our study we present clinical and molecular data from a large Italian family displaying hereditary motor and sensory neuropathy type V. Taking into account the clinical features in this family, we have performed a linkage analysis for markers strictly associated with all the known loci for autosomal dominant and autosomal recessive forms of hereditary spastic paraplegia and hereditary motor and sensory neuropathy type II, and have found no linkage to these loci. Our study suggests that hereditary motor and sensory neuropathy type V is not only a distinct clinical entity but also a distinct genetic entity.

Adult↗