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Chan ACY, Kumar S, Tan G, Wong HY, Ong JJY, Chandra B, Huang H, Sharma VK, Lai PS. Expanding the genetic causes of small-fiber neuropathy: SCN genes and beyond. Muscle Nerve 2023; 67:259-271. [PMID: 36448457 DOI: 10.1002/mus.27752] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2022] [Revised: 10/31/2022] [Accepted: 11/06/2022] [Indexed: 12/05/2022]
Abstract
Small-fiber neuropathy (SFN) is a disorder that exclusively affects the small nerve fibers, sparing the large nerve fibers. Thinly myelinated Aδ-fibers and unmyelinated C-fibers are damaged, leading to development of neuropathic pain, thermal dysfunction, sensory symptoms, and autonomic disturbances. Although many SFNs are secondary and due to immunological causes or metabolic disturbances, the etiology is unknown in up to half of the patients. Over the years, this proportion of "idiopathic SFN" has decreased, as familial and genetic causes have been discovered, thus shifting a proportion of once "idiopathic" cases to the genetic category. After the discovery of SCN9A-gene variants in 2012, SCN10A and SCN11A variants have been found to be pathogenic in SFN. With improved accessibility of SFN diagnostic tools and genetic tests, many non-SCN variants and genetically inherited systemic diseases involving the small nerve fibers have also been described, but only scattered throughout the literature. There are 80 SCN variants described as causing SFN, 8 genes causing hereditary sensory autonomic neuropathies (HSAN) described with pure SFN, and at least 7 genes involved in genetically inherited systemic diseases associated with SFN. This systematic review aims to consolidate and provide an updated overview on the genetic variants of SFN to date---SCN genes and beyond. Awareness of these genetic causes of SFN is imperative for providing treatment directions, prognostication, and management of expectations for patients and their health-care providers.
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Affiliation(s)
- Amanda C Y Chan
- Division of Neurology, Department of Medicine, National University Hospital, Singapore, Singapore
- Yong Loo Ling School of Medicine, National University of Singapore, Singapore, Singapore
| | - Shivaram Kumar
- Yong Loo Ling School of Medicine, National University of Singapore, Singapore, Singapore
| | - Grace Tan
- Yong Loo Ling School of Medicine, National University of Singapore, Singapore, Singapore
| | - Hiu Yi Wong
- Division of Life Science, State Key Laboratory of Molecular Neuroscience, Hong Kong University of Science and Technology, Hong Kong, China
- Hong Kong Center for Neurodegenerative Diseases, Hong Kong Science Park, Hong Kong, China
| | - Jonathan J Y Ong
- Division of Neurology, Department of Medicine, National University Hospital, Singapore, Singapore
- Yong Loo Ling School of Medicine, National University of Singapore, Singapore, Singapore
| | - Bharatendu Chandra
- Division of Neurology, Department of Medicine, National University Hospital, Singapore, Singapore
- Yong Loo Ling School of Medicine, National University of Singapore, Singapore, Singapore
- Division of Medical Genetics, University of Iowa, Iowa City, Iowa, USA
| | - Hua Huang
- Yong Loo Ling School of Medicine, National University of Singapore, Singapore, Singapore
| | - Vijay Kumar Sharma
- Division of Neurology, Department of Medicine, National University Hospital, Singapore, Singapore
- Yong Loo Ling School of Medicine, National University of Singapore, Singapore, Singapore
| | - Poh San Lai
- Yong Loo Ling School of Medicine, National University of Singapore, Singapore, Singapore
- Adjunct Faculty, Genome Institute of Singapore, Singapore, Singapore
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Kazamel M, Pischik E, Desnick RJ. Pain in acute hepatic porphyrias: Updates on pathophysiology and management. Front Neurol 2022; 13:1004125. [PMID: 36479055 PMCID: PMC9719963 DOI: 10.3389/fneur.2022.1004125] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2022] [Accepted: 11/07/2022] [Indexed: 11/22/2022] Open
Abstract
Acute hepatic porphyrias (AHPs) typically present with recurrent acute attacks of severe abdominal pain and acute autonomic dysfunction. While chronic symptoms were historically overlooked in the literature, recent studies have reported increased prevalence of chronic, mainly neuropathic, pain between the attacks. Here we characterize acute and chronic pain as prominent manifestations of the AHPs and discuss their pathophysiology and updated management. In addition to the severe abdominal pain, patients could experience low back pain, limb pain, and headache during acute attacks. Chronic pain between the attacks is typically neuropathic and reported mainly by patients who undergo recurrent attacks. While the acute abdominal pain during attacks is likely mediated by autonomic neuropathy, chronic pain likely represents delayed recovery of the acute neuropathy with ongoing small fiber neuropathy in addition to peripheral and/or central sensitization. δ-aminolaevulinic acid (ALA) plays a major role in acute and chronic pain via its neurotoxic effect, especially where the blood-nerve barrier is less restrictive or absent i.e., the autonomic ganglia, nerve roots, and free nerve endings. For earlier diagnosis, we recommend testing a spot urine porphobilinogen (PBG) analysis in any patient with recurrent severe acute abdominal pain with no obvious explanation, especially if associated with neuropathic pain, hyponatremia, autonomic dysfunction, or encephalopathy. Of note, it is mandatory to exclude AHPs in any acute painful neuropathy. Between the attacks, diagnostic testing for AHPs should be considered for patients with a past medical history of acute/subacute neuropathy, frequent emergency room visits with abdominal pain, and behavioral changes. Pain during the attacks should be treated with opiates combined with hemin infusions. Symptomatic treatment of chronic pain should start with gabapentinoids and certain antidepressants before opiates. Givosiran reduces levels of ALA and PBG and likely has long-term benefits for chronic pain, especially if started early during the course of the disease.
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Affiliation(s)
- Mohamed Kazamel
- Department of Neurology, University of Alabama at Birmingham, Birmingham, AL, United States
- *Correspondence: Mohamed Kazamel
| | - Elena Pischik
- Department of Neurology, Consultative and Diagnostic Center With Polyclinics, St. Petersburg, Russia
| | - Robert J. Desnick
- Department of Genetics and Genomic Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, United States
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Gerischer LM, Scheibe F, Nümann A, Köhnlein M, Stölzel U, Meisel A. Acute porphyrias - A neurological perspective. Brain Behav 2021; 11:e2389. [PMID: 34661997 PMCID: PMC8613433 DOI: 10.1002/brb3.2389] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/03/2021] [Revised: 08/21/2021] [Accepted: 09/14/2021] [Indexed: 01/23/2023] Open
Abstract
Acute hepatic porphyrias (AHP) can cause severe neurological symptoms involving the central, autonomic, and peripheral nervous system. Due to their relative rarity and their chameleon-like presentation, delayed diagnosis and misdiagnosis are common. AHPs are genetically inherited disorders that result from heme biosynthesis enzyme deficiencies and comprise four forms: acute intermittent porphyria (AIP), variegate porphyria (VP), hereditary coproporphyria (HCP), and ALA-dehydratase porphyria (ALADP). Depending on the clinical presentation, the main differential diagnoses are Guillain-Barré syndrome and autoimmune encephalitis. Red flags that could raise the suspicion of acute porphyria are neurological symptoms starting after severe (abdominal) pain, in association with reddish urine, hyponatremia or photodermatitis, and the presence of encephalopathy and/or axonal neuropathy. We highlight the diagnostic difficulties by presenting three cases from our neurological intensive care unit and give a comprehensive overview about the diagnostic findings in imaging, electrophysiology, and neuropathology.
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Affiliation(s)
- Lea M. Gerischer
- Charité – Universitätsmedizin Berlin, corporate member of Freie Universität Berlin and Humboldt‐Universität zu Berlin, Department of NeurologyBerlinGermany
- Charité – Universitätsmedizin Berlin, corporate member of Freie Universität Berlin and Humboldt‐Universität zu Berlin, NeuroCure Clinical Research CenterBerlinGermany
| | - Franziska Scheibe
- Charité – Universitätsmedizin Berlin, corporate member of Freie Universität Berlin and Humboldt‐Universität zu Berlin, Department of NeurologyBerlinGermany
- Charité – Universitätsmedizin Berlin, corporate member of Freie Universität Berlin and Humboldt‐Universität zu Berlin, NeuroCure Clinical Research CenterBerlinGermany
| | - Astrid Nümann
- Charité – Universitätsmedizin Berlin, corporate member of Freie Universität Berlin and Humboldt‐Universität zu Berlin, Department of NeurologyBerlinGermany
| | - Martin Köhnlein
- Charité – Universitätsmedizin Berlin, corporate member of Freie Universität Berlin and Humboldt‐Universität zu Berlin, Department of NeurologyBerlinGermany
| | - Ulrich Stölzel
- Department of Internal Medicine II, Porphyria Center SaxoniaKlinikum Chemnitz gGmbHChemnitzGermany
| | - Andreas Meisel
- Charité – Universitätsmedizin Berlin, corporate member of Freie Universität Berlin and Humboldt‐Universität zu Berlin, Department of NeurologyBerlinGermany
- Charité – Universitätsmedizin Berlin, corporate member of Freie Universität Berlin and Humboldt‐Universität zu Berlin, NeuroCure Clinical Research CenterBerlinGermany
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Oliveira Santos M, Leal Rato M. Neurology of the acute hepatic porphyrias. J Neurol Sci 2021; 428:117605. [PMID: 34375916 DOI: 10.1016/j.jns.2021.117605] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2021] [Revised: 07/01/2021] [Accepted: 08/01/2021] [Indexed: 11/30/2022]
Abstract
Porphyrias are a set of rare inherited metabolic disorders, each of them representing a defect in one of the eight enzymes in the haem biosynthetic pathway resulting in the accumulation of organic compounds called porphyrins. Acute hepatic porphyrias (AHP) are those in which the enzyme deficiency occurs in the liver, of which acute intermittent porphyria is by far the most common subtype. Neurology of the AHP is still challenging in practice, and patients rarely receive the correct diagnosis early in the disease course. For AHP, which primarily affects the central and peripheral nervous system, the cause of symptoms seems to be the increased production of neurotoxic precursors, in particular delta-aminolaevulinic acid and porphobilinogen. Neurological complications usually result from severe episodes of acute attacks. The neurologic hallmark of porphyrias is an acute predominantly motor axonal neuropathy resembling a Guillain-Barré syndrome that generally occurs after the onset of other clinical features such as abdominal pain and central nervous system manifestations. Neuropsychiatric syndromes, seizures, encephalopathy, and cerebrovascular disorders are among the possible central nervous system presentations. Therapeutic approach to AHP is divided into management and prophylaxis of an acute attack, including long standing options such as intravenous hematin and new therapeutic agents such as givosiran.
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Affiliation(s)
- Miguel Oliveira Santos
- Neurology, Department of Neurosciences and Mental Health, Hospital de Santa Maria, Centro Hospitalar Universitário Lisboa Norte, Lisboa, Portugal; Institute of Physiology Unit, Instituto de Medicina Molecular, Faculty of Medicine, University of Lisbon, Lisbon, Portugal.
| | - Miguel Leal Rato
- Neurology, Department of Neurosciences and Mental Health, Hospital de Santa Maria, Centro Hospitalar Universitário Lisboa Norte, Lisboa, Portugal; Institute of Pharmacology and Neurosciences, Faculty of Medicine, University of Lisbon, Lisbon, Portugal
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Gandhi Mehta RK, Caress JB, Rudnick SR, Bonkovsky HL. Porphyric neuropathy. Muscle Nerve 2021; 64:140-152. [PMID: 33786855 DOI: 10.1002/mus.27232] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2020] [Revised: 03/10/2021] [Accepted: 03/14/2021] [Indexed: 12/15/2022]
Abstract
Acute hepatic porphyrias are inherited metabolic disorders that may present with polyneuropathy, which if not diagnosed early can lead to quadriparesis, respiratory weakness, and death. Porphyric neuropathy is an acute to subacute motor predominant axonal neuropathy with a predilection for the upper extremities and usually preceded by a predominantly parasympathetic autonomic neuropathy. The rapid progression and associated dysautonomia mimic Guillain-Barré syndrome but are distinguished by the absence of cerebrospinal fluid albuminocytologic dissociation, progression beyond 4 wk, and associated abdominal pain. Spot urine test to assess the porphyrin precursors delta-aminolevulinic acid and porphobilinogen can provide a timely diagnosis during an acute attack. Timely treatment with intravenous heme, carbohydrate loading, and avoidance of porphyrinogenic medications can prevent further neurological morbidity and mortality.
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Affiliation(s)
| | - James B Caress
- Department of Neurology, Wake Forest Baptist Health, Winston Salem, North Carolina, USA
| | - Sean R Rudnick
- Section on Gastroenterology & Hepatology, Department of Internal Medicine, Wake Forest Baptist health, Winston Salem, North Carolina, USA
| | - Herbert L Bonkovsky
- Section on Gastroenterology & Hepatology, Department of Internal Medicine, Wake Forest Baptist health, Winston Salem, North Carolina, USA
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Porphyric Neuropathy: Pathophysiology, Diagnosis, and Updated Management. Curr Neurol Neurosci Rep 2020; 20:56. [PMID: 33026560 DOI: 10.1007/s11910-020-01078-8] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/29/2020] [Indexed: 12/20/2022]
Abstract
PURPOSE OF REVIEW To review the peripheral neurological complications of the acute hepatic porphyrias, as well as the latest advances in their pathophysiology and management. RECENT FINDINGS The diagnosis of porphyric neuropathy remains challenging as varying neuropathic patterns are encountered depending on disease stage, including a non-length-dependent distribution pattern. The major pathophysiologic mechanism is δ-aminolevulinic acid (ALA)-induced neurotoxicity. The less restrictive blood-nerve barrier in the autonomic ganglia and myenteric plexus may explain the frequency of dysautonomic manifestations. Recently, a prophylactic small interfering RNA (siRNA)-based therapy that reduces hepatic ALA Synthase-1 mRNA was approved for patients with recurrent neuro-visceral attacks. Neurologists should appreciate the varying patterns of porphyric neuropathy. As with most toxin-induced axonopathies, long-term outcomes depend on early diagnosis and treatment. While the short-term clinical and biochemical benefits of siRNA-based therapy are known, its long-term effects on motor recovery, chronic pain, and dysautonomic manifestations are yet to be determined.
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Abstract
Despite medical advances, the diagnosis and management of acute intermittent porphyria continues to be challenging. Acute pain is one of the most important clinical manifestations in acute intermittent porphyria, but management and pain assessment have been poorly studied in these patients. The lack of information and evidence based recommendations regarding these topics in the medical literature is certainly surprising. Furthermore, pain management is discussed based on extrapolating concepts adopted for other pain syndromes. An important arsenal of medications, including reportedly safe opioid and non-opioid analgesics, is available for use in this type of patient. In addition to conducting an extensive review of the current literature, the present article aims to show the general aspects of a disease that generates a challenge for the clinician, emphasizing what is related to pain as a cardinal symptom and to create awareness about the need for studies supporting the development of guidelines, based on evidence obtained from analgesic management in patients presenting with this disorder. A systematic assessment directed at understanding the physiopathological processes underlying acute pain combined with a stepwise approach to pain management with safe opioid and non-opioid drugs constitutes the fundamental basis for a successful pain management program in patients with acute intermittent porphyria.
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Simon NG, Herkes GK. The neurologic manifestations of the acute porphyrias. J Clin Neurosci 2011; 18:1147-53. [DOI: 10.1016/j.jocn.2011.01.003] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2010] [Revised: 01/11/2011] [Accepted: 01/26/2011] [Indexed: 12/17/2022]
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Tébar MT, Aguilera L. [Acute intermittent porphyria and inappropriate ADH syndrome]. ACTA ACUST UNITED AC 2010; 57:311-3. [PMID: 20527347 DOI: 10.1016/s0034-9356(10)70233-4] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
A 44-year-old woman complained of abdominal pain of 4 days' duration accompanied by vomiting and painful urination. The admitting physician noted neurologic signs consistent with axonal polyneuropathy and hyponatremia. In the absence of other explanations for the syndrome, SIADH was diagnosed. Because of the nonspecific nature of the observations, the patient was assessed by various specialists and admitted to the anesthetic recovery unit due to worsening of neurologic signs and suspicion of acute intermittent porphyria. The diagnosis was confirmed by laboratory findings of elevated d-aminolevulinic acid and porphobilinogen levels and normal stool porphyrins. The patient improved with intravenous hematin infused over 4 days.
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Affiliation(s)
- M T Tébar
- Servicio de Anestesiología y Reanimación, Hospital de Basurto, Bilbao.
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Abstract
PURPOSE OF REVIEW To give an overview of recent data on the use of skin biopsy as a diagnostic tool in neuropathies. RECENT FINDINGS The sensitivity and specificity of skin biopsy in detecting small fiber neuropathy is supported by new data. In many patients with small fiber neuropathy, a treatable disorder can be identified if a full workup is done. Skin innervation is affected in neuropathies formerly considered as the large fiber type, such as porphyria and chronic inflammatory demyelinating neuropathy. New methods have been devised to complement histological evaluation of skin innervation by in-vivo microscopy and by neurophysiological assessment of small nerve fibers. Skin biopsies have been used to learn more about the pathophysiology of neuropathies, such as the discovery of reduced vascular endothelial growth factor expression in diabetic neuropathy and the increase in cytokine expression in some painful small fiber neuropathies. Quantification of skin innervation has been used as a measure for treatment success in experimental studies and is presently used for follow-up in clinical trials. SUMMARY Skin biopsy in the diagnosis of neuropathy is moving from a method giving descriptive results to a tool that may be helpful in etiological diagnostics, as a follow-up in clinical trials, and in pathophysiological research.
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