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Peripheral Autonomic Neuropathies
Published in David Robertson, Italo Biaggioni, Disorders of the Autonomic Nervous System, 2019
Two distinct categories are recognizable, the first with known metabolic disorders, examples being porphyria and inherited amyloid neuropathies, and in the latter category without metabolic abnormalities, which usually also include symptomatic sensory impairment occurring together with autonomic dysfunction. This group is now referred to as hereditary sensory and autonomic neuropathies.
Charcot-Marie-Tooth Disease: Disorder or Syndrome?
Published in Leon I. Charash, Robert E. Lovelace, Claire F. Leach, Austin H. Kutscher, Rabbi Jacob Goldberg, David Price Roye, Jill C. Crabtree, Muscular Dystrophy and Other Neuromuscular Diseases: Psychosocial Issues, 2014
Interestingly, the unusual cases such as those with spasticity (Type 5), optic atrophy (Type 6), retinitis pigmentosa (Type 7) and other atypical or associated features may make up 30% of our total experience and have the same physical appearance (called the phenotype). They also exhibit a similar range of inheritance patterns, can be entirely distal motor or spinal muscular atrophy with normal motor and sensory conduction (spinal type) or may have a defined storage disorder, such as phytanic acid (a fatty acid) in the recessive disease, Refsum’s disease or Type 4.1.3 The hereditary sensory and autonomic neuropathies usually have much earlier onset but occasionally very similar deformities and are classified as Types 1 to 4,4 and an extremely severe disease with onset at birth or in early infancy, the congenital hypomyelination syndrome is almost certainly a genetic disorder with similarities to these and the Type 3 or Dejerine Sottas disorder.
Electrodiagnosis
Published in Mark V. Boswell, B. Eliot Cole, Weiner's Pain Management, 2005
Ross E. Lipton, David M. Glick
Certain painful neuropathies, such as hereditary sensory and autonomic neuropathies (HSAN) and those associated with porphyria, have a prominent autonomic component. The quantitative sudomotor axon reflex test (QSART) assesses autonomic (small) fiber dysfunction via the sweat response and is considered to be a reliable test with good reproducibility. Acetylcholine (ACH) is the key to QSART. It is used as an exogenous stimulator of the sweat response as well as the endogenous mediator of that response. Iontophoresed (exogenous) ACH activates antidromic axonal transmission, which eventually becomes orthodromic after turning at a branch, ultimately stimulating release of synaptic (endogenous) ACH. The released synaptic ACH that binds to the M3 muscarinic receptor on the sweat gland is quantified by a “sudometer” reading of the multicompartment sweat capsule that collected the released ACH (Jaradeh & Prieto, 2003). In neuropathy, multiple sites are tested. Small fiber nerve damage may be reflected by a reduced or absent sweat response. As well, a small fiber neuropathy may be characterized by an excessive or a persistent sweat response. The sweat response also has a latency, which is measured from commencement of iontophoresis to the moment of sweat secretion. Prolonged latency suggests small fiber dysfunction. Conversely, relatively shortened sweat response latency, less than 1 minute, is consistent with sympathetic overactivity.
A Child Presenting with Recurrent Corneal Ulcers: Hereditary Sensory and Autonomic Neuropathy IV (HSAN IV)
Published in Neuro-Ophthalmology, 2019
Beena Suresh, Vaishnavi Reddy, Ingo Kurth, Sujatha Jagadeesh
Corneal ulcers that develop due to decrease or absence of corneal sensation are called neurotrophic corneal ulcers. These ulcers can be due to systemic illness, ocular disease, congenital or iatrogenic diseases that lead to damage to the fifth cranial nerve, which is responsible for corneal innervation.1 Among the congenital causes, hereditary sensory and autonomic neuropathies (HSAN) forms an important group which should be considered especially when the patient presents with recurrent corneal ulcers and systemic manifestations.
Isolated juvenile macular dystrophy without posterior column ataxia associated with FLVCR1 mutation
Published in Ophthalmic Genetics, 2021
Eva S. Lachmann, Luca Mautone, Simon Dulz
Mutation in the FLVCR1 gene has been recognized to result in progressive retinitis pigmentosa with a variable degree of neurologic involvement. Neurologic involvement ranged between the initially described sensory ataxia secondary to degeneration of the posterior columns and loss of proprioception (3) to hereditary sensory and autonomic neuropathies (HSANs) (4–6). Yet, a number of cases described in the literature revealed no neurologic involvement (7,8).
Association of small-fiber polyneuropathy with three previously unassociated rare missense SCN9A variants
Published in Canadian Journal of Pain, 2020
Mary A. Kelley, Anne Louise Oaklander
Pathogenic single nucleotide polymorphisms (SNPs) that alter proteins (nonconservative or missense mutations) preferentially expressed by small fibers are another increasingly discussed contributor to SFN. These include several of the historically named hereditary sensory and autonomic neuropathies (types 1 to 5), X-linked Fabry disease, autosomal-dominant transthyretin amyloidosis, and mutations affecting small fiber ion channels including the Nav1.6–1.9 sodium channels as well as the HCN2, TRPA1, TRPV4, and Piezo2 channels (reviewed in Oaklander and Nolano1). Ion channels are intermembrane gated pores that regulate voltage potential across the axolemma by controlling ion flow between the intracellular and extracellular compartments. Their openings and closings produce electrical signals that cause adjacent voltage-sensitive channels to open, thus initiating and propagating the action potentials that neurons use to transmit information. Of approximately 215 ion channels found in humans, 85 are linked to pain.29 The most important channels preferentially expressed on pain-sensing small fiber axons are the voltage-gated sodium (Nav) channel family: Nav1.7, Nav1.8, and Nav 1.9. These are encoded for by the SCN9A, 10A, and 11A genes, respectively.30,31 Various deterministic (Mendelian) autosomal-dominant gain-of-function and loss-of-function Nav mutations have been associated with familial and sporadic pain and itch abnormalities, with SCN9A most commonly reported.32–36 There may be regional differences; a U.S. study of mixed neuropathy patients reported no correlations between the presence of Nav variants and pain status,37 whereas a Dutch study of 1139 patients with pure clinically defined SFN reported that 11.6% harbored 73 potentially pathogenic variants in voltage-gated sodium channels, specifically 5.1% for SCN9A, 3.7% for SCN10A, and 2.9% for SCN11A.38 Among Dutch patients with neuropathy symptoms, only the presence of “erythromelalgia” and “warmth-induced pain” symptoms was more common in patients harboring Nav variants.38