Alex Incensi

Skin nerve α-synuclein deposits: a biomarker for idiopathic Parkinson disease.

Objective:To investigate (1) whether phosphorylated &agr;-synuclein deposits in skin nerve fibers might represent a useful biomarker for idiopathic Parkinson disease (IPD), and (2) the underlying pathogenesis of peripheral neuropathy associated with IPD. Methods:Twenty-one well-characterized patients with IPD were studied together with 20 patients with parkinsonisms assumed not to have &agr;-synuclein deposits (PAR; 10 patients fulfilling clinical criteria for vascular parkinsonism, 6 for tauopathies, and 4 with parkin mutations) and 30 controls. Subjects underwent nerve conduction velocities from the leg to evaluate large nerve fibers and skin biopsy from proximal (i.e., cervical) and distal (i.e., thigh and distal leg) sites to study small nerve fibers and deposits of phosphorylated &agr;-synuclein considered the pathologic form of &agr;-synuclein. Results:Patients with IPD showed a small nerve fiber neuropathy prevalent in the leg with preserved large nerve fibers. PAR patients showed normal large and small nerve fibers. Phosphorylated &agr;-synuclein was not found in any skin sample in PAR patients and controls, but it was found in all patients with IPD in the cervical skin site. Abnormal deposits were correlated with leg epidermal denervation. Conclusions:The search for phosphorylated &agr;-synuclein in proximal peripheral nerves is a sensitive biomarker for IPD diagnosis, helping to differentiate IPD from other parkinsonisms. Neuritic inclusions of &agr;-synuclein were correlated with a small-fiber neuropathy, suggesting their direct role in peripheral nerve fiber damage. Classification of evidence:This study provides Class III evidence that the presence of phosphorylated &agr;-synuclein in skin nerve fibers on skin biopsy accurately distinguishes IPD from other forms of parkinsonism.Objective: To investigate (1) whether phosphorylated α-synuclein deposits in skin nerve fibers might represent a useful biomarker for idiopathic Parkinson disease (IPD), and (2) the underlying pathogenesis of peripheral neuropathy associated with IPD. Methods: Twenty-one well-characterized patients with IPD were studied together with 20 patients with parkinsonisms assumed not to have α-synuclein deposits (PAR; 10 patients fulfilling clinical criteria for vascular parkinsonism, 6 for tauopathies, and 4 with parkin mutations) and 30 controls. Subjects underwent nerve conduction velocities from the leg to evaluate large nerve fibers and skin biopsy from proximal (i.e., cervical) and distal (i.e., thigh and distal leg) sites to study small nerve fibers and deposits of phosphorylated α-synuclein considered the pathologic form of α-synuclein. Results: Patients with IPD showed a small nerve fiber neuropathy prevalent in the leg with preserved large nerve fibers. PAR patients showed normal large and small nerve fibers. Phosphorylated α-synuclein was not found in any skin sample in PAR patients and controls, but it was found in all patients with IPD in the cervical skin site. Abnormal deposits were correlated with leg epidermal denervation. Conclusions: The search for phosphorylated α-synuclein in proximal peripheral nerves is a sensitive biomarker for IPD diagnosis, helping to differentiate IPD from other parkinsonisms. Neuritic inclusions of α-synuclein were correlated with a small-fiber neuropathy, suggesting their direct role in peripheral nerve fiber damage. Classification of evidence: This study provides Class III evidence that the presence of phosphorylated α-synuclein in skin nerve fibers on skin biopsy accurately distinguishes IPD from other forms of parkinsonism.

Small nerve fiber involvement in patients referred for fibromyalgia

Introduction: Fibromyalgia (FM) is a chronic syndrome characterized by widespread pain often accompanied by other symptoms suggestive of neuropathic pain. We evaluated patients for small fiber neuropathy (SFN) who were referred for fibromyalgia (FM). Methods: We studied 20 consecutive subjects with primary FM. Patients underwent neurological examination, nerve conduction studies, and skin biopsies from distal leg and thigh. Results: Electrodiagnostic studies were normal in all patients. SFN was diagnosed in 6 patients by reduced epidermal nerve fiber density. These patients also showed abnormalities of both adrenergic and cholinergic fibers. Conclusions: A subset of FM subjects have SFN, which may contribute to their sensory and autonomic symptoms. Skin biopsy should be considered in the diagnostic work‐up of FM. Muscle Nerve 49: 757–759, 2014

Skin nerve misfolded α-synuclein in pure autonomic failure and Parkinson disease

To characterize the expression in skin nerves of native (n‐syn) and misfolded phosphorylated (p‐syn) α‐synucleins in pure autonomic failure (PAF) and idiopathic Parkinson disease (IPD). The specific aims were to (1) define the importance of n‐syn and p‐syn as disease biomarkers and (2) ascertain differences in abnormal synuclein skin nerve deposits.

Skin nerve phosphorylated α-synuclein deposits in idiopathic REM sleep behavior disorder

Objective: To test if phosphorylated α-synuclein (p-α-syn) deposits can be detected by means of skin biopsy in patients with idiopathic REM sleep behavior disorder (iRBD) as a potential early histopathologic marker of impending synucleinopathy. Methods: Proximal (cervical) and distal (legs) samples of skin biopsy were obtained from 12 patients with polysomnographically confirmed iRBD and 55 sex- and age-matched healthy controls (HC). P-α-syn deposits were assessed with a monoclonal antibody against p-α-syn at serine 129, disclosed by an immunofluorescence method. In addition, patients underwent an extensive workup in order to search for nonmotor symptoms and neuroimaging findings usually associated with impending neurodegeneration and to exclude subtle motor or cognitive signs. Results: P-α-syn deposits were detected in 9 (75%) out of 12 patients with iRBD and none of the HC. In iRBD, the sensitivity of the test was higher at the cervical site (67%) when compared to the leg site (58%). Conclusions: Our preliminary findings suggest that skin biopsy in patients with iRBD might be a safe and sensitive procedure to be further tested in order to detect p-α-syn deposits in the premotor stage of synucleinopathies. Classification of evidence: This study provides Class III evidence that p-α-syn skin deposits identify patients with iRBD.

Peripheral Autonomic Neuropathy: Diagnostic Contribution of Skin Biopsy

Abstract Skin biopsy has gained widespread use for the diagnosis of somatic small-fiber neuropathy, but it also provides information on sympathetic fiber morphology. We aimed to ascertain the diagnostic accuracy of skin biopsy in disclosing sympathetic nerve abnormalities in patients with autonomic neuropathy. Peripheral nerve fiber autonomic involvement was confirmed by routine autonomic laboratory test abnormalities. Punch skin biopsies were taken from the thigh and lower leg of 28 patients with various types of autonomic neuropathy for quantitative evaluation of skin autonomic innervation. Results were compared with scores obtained from 32 age-matched healthy controls and 25 patients with somatic neuropathy. The autonomic cutoff score was calculated using the receiver operating characteristic curve analysis. Skin biopsy disclosed a significant autonomic innervation decrease in autonomic neuropathy patients versus controls and somatic neuropathy patients. Autonomic innervation density was abnormal in 96% of patients in the lower leg and in 79% of patients in the thigh. The abnormal findings disclosed by routine autonomic tests ranged from 48% to 82%. These data indicate the high sensitivity and specificity of skin biopsy in detecting sympathetic abnormalities; this method should be useful for the diagnosis of autonomic neuropathy, together with currently available routine autonomic testing.

Skin sympathetic fiber α-synuclein deposits: A potential biomarker for pure autonomic failure

Objective: This study aimed to test whether peripheral α-synuclein staining might be useful for pure autonomic failure (PAF) diagnosis, helping to differentiate degenerative from acquired peripheral autonomic neuropathy. Methods: We studied 21 patients with chronic peripheral autonomic neuropathy showing sympathetic and parasympathetic involvement as confirmed by cardiovascular reflexes and microneurography from the peroneal nerve. Twelve patients showed a specific cause of neuropathy (acquired autonomic neuropathy) whereas 9 had no specific acquired causes fulfilling the diagnostic criteria for PAF. Fifteen matched healthy subjects served as controls. Subjects underwent skin biopsy from thigh and leg to study skin innervation and phosphorylated α-synuclein deposits in the peripheral axons. Results: Somatic and autonomic skin innervations were significantly decreased in patients with peripheral autonomic neuropathy compared to controls. No differences were found between acquired autonomic neuropathy and PAF. The deposits of α-synuclein were not found in controls but served to distinguish acquired from degenerative autonomic peripheral neuropathy: all patients with PAF showed α-synuclein deposits, which were absent in patients with acquired autonomic neuropathy. Colocalization study disclosed α-synuclein neuritic inclusions in the postganglionic sympathetic adrenergic and cholinergic nerve fibers. Conclusions: Our study demonstrated that a search for neuritic inclusions of phosphorylated α-synuclein in the skin sympathetic nerve fibers could provide a sensitive in vivo biomarker for degenerative peripheral autonomic neuropathy and may shed more light on the pathogenesis of PAF.Objective:This study aimed to test whether peripheral &agr;-synuclein staining might be useful for pure autonomic failure (PAF) diagnosis, helping to differentiate degenerative from acquired peripheral autonomic neuropathy. Methods:We studied 21 patients with chronic peripheral autonomic neuropathy showing sympathetic and parasympathetic involvement as confirmed by cardiovascular reflexes and microneurography from the peroneal nerve. Twelve patients showed a specific cause of neuropathy (acquired autonomic neuropathy) whereas 9 had no specific acquired causes fulfilling the diagnostic criteria for PAF. Fifteen matched healthy subjects served as controls. Subjects underwent skin biopsy from thigh and leg to study skin innervation and phosphorylated &agr;-synuclein deposits in the peripheral axons. Results:Somatic and autonomic skin innervations were significantly decreased in patients with peripheral autonomic neuropathy compared to controls. No differences were found between acquired autonomic neuropathy and PAF. The deposits of &agr;-synuclein were not found in controls but served to distinguish acquired from degenerative autonomic peripheral neuropathy: all patients with PAF showed &agr;-synuclein deposits, which were absent in patients with acquired autonomic neuropathy. Colocalization study disclosed &agr;-synuclein neuritic inclusions in the postganglionic sympathetic adrenergic and cholinergic nerve fibers. Conclusions:Our study demonstrated that a search for neuritic inclusions of phosphorylated &agr;-synuclein in the skin sympathetic nerve fibers could provide a sensitive in vivo biomarker for degenerative peripheral autonomic neuropathy and may shed more light on the pathogenesis of PAF.

Homozygous NOTCH3 null mutation and impaired NOTCH3 signaling in recessive early‐onset arteriopathy and cavitating leukoencephalopathy

Notch signaling is essential for vascular physiology. Neomorphic heterozygous mutations in NOTCH3, one of the four human NOTCH receptors, cause cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL). Hypomorphic heterozygous alleles have been occasionally described in association with a spectrum of cerebrovascular phenotypes overlapping CADASIL, but their pathogenic potential is unclear. We describe a patient with childhood‐onset arteriopathy, cavitating leukoencephalopathy with cerebral white matter abnormalities presented as diffuse cavitations, multiple lacunar infarctions and disseminated microbleeds. We identified a novel homozygous c.C2898A (p.C966*) null mutation in NOTCH3 abolishing NOTCH3 expression and causing NOTCH3 signaling impairment. NOTCH3 targets acting in the regulation of arterial tone (KCNA5) or expressed in the vasculature (CDH6) were downregulated. Patients vessels were characterized by smooth muscle degeneration as in CADASIL, but without deposition of granular osmiophilic material (GOM), the CADASIL hallmark. The heterozygous parents displayed similar but less dramatic trends in decrease in the expression of NOTCH3 and its targets, as well as in vessel degeneration. This study suggests a functional link between NOTCH3 deficiency and pathogenesis of vascular leukoencephalopathies.

Spine Topographical Distribution of Skin α-Synuclein Deposits in Idiopathic Parkinson Disease

Phosphorylated α-synuclein (p-syn) in skin nerves mainly in the proximal sites is a promising neurodegenerative biomarker for idiopathic Parkinson disease (IPD). However, the p-syn spine distribution particularly in patients with unilateral motor dysfunctions remains undefined. This study aimed to investigate in IPD p-syn differences between left and right cervical spine sites in patients with prevalent unilateral motor symptoms, and cervical and thoracic spine sites in patients with bilateral motor symptoms. We enrolled 28 IPD patients fulfilling clinical diagnostic criteria associated with abnormal nigro-striatal DatScan and cardiac MIBG: 15 with prevalently unilateral motor symptoms demonstrated by DatScan; 13 with bilateral motor symptoms and DatScan abnormalities. Patients underwent skin biopsy searching for intraneural p-syn deposits: skin samples were taken from C7 paravertebral left and right sites in unilateral patients and from cervical (C7) and thoracic (Th12) paravertebral spine regions in bilateral patients. Unilateral patients displayed 20% of abnormal p-syn deposits in the affected motor site, 60% in both sites and 20% only in the non-affected site. P-syn was found in all patients in C7 but in only 62% of patients in Th12. Our data showed that cervical p-syn deposits displayed a uniform distribution between both sides not following the motor dysfunction in unilateral patients, and skin nerve p-syn deposits demonstrated a spine gradient with the cervical site expressing the highest positivity.

Skin biopsy and I-123 MIBG scintigraphy findings in idiopathic Parkinson's disease and parkinsonism: A comparative study

123I‐meta‐iodobenzylguanidine (123I‐MIBG) myocardial scintigraphy is considered reliable in differentiating idiopathic Parkinsons disease (IPD) from other parkinsonisms, but it is biased by pharmacological treatments. Skin biopsy is not influenced by therapy and has disclosed skin denervation in IPD. Our aims were to compare 123I‐MIBG scintigraphy and skin biopsy findings in IPD and parkinsonisms to (1) verify whether myocardial and skin denervations are linked; (2) explore the simultaneous extent of the autonomic dysfunction.

Post-ganglionic autonomic neuropathy associated with anti-glutamic acid decarboxylase antibodies

PurposeAntibodies to glutamic acid decarboxylase (GAD-Abs) have been associated with several conditions, rarely involving the autonomic nervous system. Here, we describe two patients complaining of autonomic symptoms in whom a post-ganglionic autonomic neuropathy has been demonstrated in association with significantly elevated serum and CSF GAD-Abs levels.MethodsPatients underwent nerve conduction studies, sympathetic skin response testing, evaluation of autonomic control of the cardiovascular system and skin biopsy. Also, serum screening to exclude predisposing causes of peripheral neuropathy was performed. Anti-GAD65 antibodies were evaluated in serum and CSF.ResultsGAD-Abs titer was increased in both serum and CSF in both patients. Sympathetic skin response was absent and skin biopsy revealed a non-length-dependent small-fiber neuropathy with sympathetic cholinergic and adrenergic post-ganglionic damage in both patients. Nerve conduction studies and evaluation of autonomic control of the cardiovascular system were normal in both patients. Both patients were treated with steroids with good, but partial, (patient 2) recovery of the autonomic dysfunctions.ConclusionsAlthough the pathophysiological mechanisms involved are not fully defined, GAD-abs positivity in serum and CSF should be searched in patients with autonomic neuropathy when no other acquired causes are evident. This positivity may help to clarify autoimmune etiology and, subsequently, to consider immunomodulatory treatment.