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Macefield VG, Smith LJ, Norcliffe‐Kaufmann L, Palma J, Kaufmann H. Sensorimotor control in the congenital absence of functional muscle spindles. Exp Physiol 2024; 109:27-34. [PMID: 37029664 PMCID: PMC10988665 DOI: 10.1113/ep090768] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2023] [Accepted: 03/22/2023] [Indexed: 04/09/2023]
Abstract
Hereditary sensory and autonomic neuropathy type III (HSAN III), also known as familial dysautonomia or Riley-Day syndrome, results from an autosomal recessive genetic mutation that causes a selective loss of specific sensory neurones, leading to greatly elevated pain and temperature thresholds, poor proprioception, marked ataxia and disturbances in blood pressure control. Stretch reflexes are absent throughout the body, which can be explained by the absence of functional muscle spindle afferents - assessed by intraneural microelectrodes inserted into peripheral nerves in the upper and lower limbs. This also explains the greatly compromised proprioception at the knee joint, as assessed by passive joint-angle matching. Moreover, there is a tight correlation between loss of proprioceptive acuity at the knee and the severity of gait impairment. Surprisingly, proprioception is normal at the elbow, suggesting that participants are relying more on sensory cues from the overlying skin; microelectrode recordings have shown that myelinated tactile afferents in the upper and lower limbs appear to be normal. Nevertheless, the lack of muscle spindles does affect sensorimotor control in the upper limb: in addition to poor performance in the finger-to-nose test, manual performance in the Purdue pegboard task is much worse than in age-matched healthy controls. Unlike those rare individuals with large-fibre sensory neuropathy, in which both muscle spindle and cutaneous afferents are absent, those with HSAN III present as a means of assessing sensorimotor control following the selective loss of muscle spindle afferents.
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Affiliation(s)
| | - Lyndon J. Smith
- School of MedicineWestern Sydney UniversitySydneyNew South WalesAustralia
| | - Lucy Norcliffe‐Kaufmann
- Dysautonomia Center, Department of NeurologyNew York University School of MedicineNew YorkNYUSA
| | - Jose‐Alberto Palma
- Dysautonomia Center, Department of NeurologyNew York University School of MedicineNew YorkNYUSA
| | - Horacio Kaufmann
- Dysautonomia Center, Department of NeurologyNew York University School of MedicineNew YorkNYUSA
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2
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Yang QH, Wang XQ. Lumbar joint position sense measurement of patients with low back pain. EFORT Open Rev 2023; 8:639-650. [PMID: 37526253 PMCID: PMC10441253 DOI: 10.1530/eor-23-0077] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 08/02/2023] Open
Abstract
Lumbar position sense can be assessed by measurement instruments including the goniometer, isokinetic dynamometry, and electronic motion monitoring equipment, which have demonstrated relatively high reliability. This literature provides a comprehensive overview of influencing factors of lumbar position sense measurement, including repositioning method, fatigue degree, and posture during the reposition. It highlights the significant role of muscle proprioception, which contributes to greater accuracy in active reposition compared to passive reposition. The differences in lumbar position sense with different measurement positions may be explained by the presence of mechanoreceptors in the load-bearing structures of the lumbar spine, especially in the facet joint capsules. These mechanoreceptors play a crucial role in providing sensory feedback and proprioceptive information pertaining to the position and movement of the lumbar spine. Individuals with low back pain (LBP) demonstrate alterations in lumbar position sense compared to those without LBP. The auto motor sensory feedback transmission mechanism of patients with non-specific LBP was more unstable than that of healthy people. These findings suggest that lumbar position sense may play a potential role in the development and perpetuation of LBP. At present, the commonly used clinical assessment methods for determining position sense include both active and passive repositioning. However, neither method exhibits high sensitivity and specificity, leading to the poor comparability of relevant studies and posing challenges for clinical application.
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Affiliation(s)
- Qi-Hao Yang
- Department of Sport Rehabilitation, Shanghai University of Sport, Shanghai, China
| | - Xue-Qiang Wang
- Department of Sport Rehabilitation, Shanghai University of Sport, Shanghai, China
- Department of Rehabilitation Medicine, Shanghai Shangti Orthopaedic Hospital, Shanghai, China
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Morini E, Chekuri A, Logan EM, Bolduc JM, Kirchner EG, Salani M, Krauson AJ, Narasimhan J, Gabbeta V, Grover S, Dakka A, Mollin A, Jung SP, Zhao X, Zhang N, Zhang S, Arnold M, Woll MG, Naryshkin NA, Weetall M, Slaugenhaupt SA. Development of an oral treatment that rescues gait ataxia and retinal degeneration in a phenotypic mouse model of familial dysautonomia. Am J Hum Genet 2023; 110:531-547. [PMID: 36809767 PMCID: PMC10027479 DOI: 10.1016/j.ajhg.2023.01.019] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2022] [Accepted: 01/30/2023] [Indexed: 02/22/2023] Open
Abstract
Familial dysautonomia (FD) is a rare neurodegenerative disease caused by a splicing mutation in elongator acetyltransferase complex subunit 1 (ELP1). This mutation leads to the skipping of exon 20 and a tissue-specific reduction of ELP1, mainly in the central and peripheral nervous systems. FD is a complex neurological disorder accompanied by severe gait ataxia and retinal degeneration. There is currently no effective treatment to restore ELP1 production in individuals with FD, and the disease is ultimately fatal. After identifying kinetin as a small molecule able to correct the ELP1 splicing defect, we worked on its optimization to generate novel splicing modulator compounds (SMCs) that can be used in individuals with FD. Here, we optimize the potency, efficacy, and bio-distribution of second-generation kinetin derivatives to develop an oral treatment for FD that can efficiently pass the blood-brain barrier and correct the ELP1 splicing defect in the nervous system. We demonstrate that the novel compound PTC258 efficiently restores correct ELP1 splicing in mouse tissues, including brain, and most importantly, prevents the progressive neuronal degeneration that is characteristic of FD. Postnatal oral administration of PTC258 to the phenotypic mouse model TgFD9;Elp1Δ20/flox increases full-length ELP1 transcript in a dose-dependent manner and leads to a 2-fold increase in functional ELP1 in the brain. Remarkably, PTC258 treatment improves survival, gait ataxia, and retinal degeneration in the phenotypic FD mice. Our findings highlight the great therapeutic potential of this novel class of small molecules as an oral treatment for FD.
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Affiliation(s)
- Elisabetta Morini
- Center for Genomic Medicine, Massachusetts General Hospital Research Institute, Boston, MA, USA; Department of Neurology, Massachusetts General Hospital Research Institute and Harvard Medical School, Boston, MA, USA.
| | - Anil Chekuri
- Center for Genomic Medicine, Massachusetts General Hospital Research Institute, Boston, MA, USA; Department of Neurology, Massachusetts General Hospital Research Institute and Harvard Medical School, Boston, MA, USA; Grousbeck Gene Therapy Center, Schepens Eye Research Institute and Massachusetts Eye and Ear Infirmary, Boston, MA, USA
| | - Emily M Logan
- Center for Genomic Medicine, Massachusetts General Hospital Research Institute, Boston, MA, USA
| | - Jessica M Bolduc
- Center for Genomic Medicine, Massachusetts General Hospital Research Institute, Boston, MA, USA
| | - Emily G Kirchner
- Center for Genomic Medicine, Massachusetts General Hospital Research Institute, Boston, MA, USA
| | - Monica Salani
- Center for Genomic Medicine, Massachusetts General Hospital Research Institute, Boston, MA, USA
| | - Aram J Krauson
- Center for Genomic Medicine, Massachusetts General Hospital Research Institute, Boston, MA, USA
| | | | | | | | - Amal Dakka
- PTC Therapeutics, Inc., South Plainfield, NJ 07080, USA
| | - Anna Mollin
- PTC Therapeutics, Inc., South Plainfield, NJ 07080, USA
| | | | - Xin Zhao
- PTC Therapeutics, Inc., South Plainfield, NJ 07080, USA
| | - Nanjing Zhang
- PTC Therapeutics, Inc., South Plainfield, NJ 07080, USA
| | - Sophie Zhang
- PTC Therapeutics, Inc., South Plainfield, NJ 07080, USA
| | | | | | | | - Marla Weetall
- PTC Therapeutics, Inc., South Plainfield, NJ 07080, USA
| | - Susan A Slaugenhaupt
- Center for Genomic Medicine, Massachusetts General Hospital Research Institute, Boston, MA, USA; Department of Neurology, Massachusetts General Hospital Research Institute and Harvard Medical School, Boston, MA, USA.
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Shang XD, Zhang EM, Chen ZL, Zhang L, Qian JH. Correlation analysis of national elite Chinese male table tennis players’ shoulder proprioception and muscle strength. World J Clin Cases 2022; 10:8514-8524. [PMID: 36157833 PMCID: PMC9453366 DOI: 10.12998/wjcc.v10.i24.8514] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/22/2022] [Revised: 03/28/2022] [Accepted: 07/18/2022] [Indexed: 02/05/2023] Open
Abstract
BACKGROUND Shoulder is the most injured part in table tennis players, and it takes multiple roles in transmitting power and striking the center of the ball during the stroke. Proprioception is strongly correlated with high level of athletic performance. It is customary to assume that there is a correlation between proprioception and muscle strength and therefore proprioceptive assessment and rehabilitation is often neglected.
AIM To investigate the correlation between isokinetic muscle strength and proprioception in the internal and external rotation muscle groups of elite Chinese male table tennis players, to provide reference for physical training and rehabilitation of elite table tennis players.
METHODS A total of 19 national elite table tennis players from the Chinese National Table Tennis Team were recruited in this research. All of them had more than 10 years training experience and had participated major competitions such as the National Games and World Youth Championships. IsoMed 2000 was used to test the peak torque of internal and external rotation isokinetic concentric contraction of the athletes' bilateral shoulder joints at low speed (60°/s) and high speed (180°/s) respectively; IsoMed 2000 was used to conduct the Joint Position Reproduction test to evaluate the athletes' proprioceptive ability capacity at low speed (60°/s) and high speed (180°/s) respectively. If the data satisfied the normal distribution, the correlation between the differences in peak torque s and angles in different directions was analyzed using a Pearson simple linear model; otherwise, Spearman correlation analysis was used. The comparison of proprioceptive ability between the table tennis racket-holding hand and non-racket-holding hands was performed using independent samples t-test if the data satisfied a normal distribution; otherwise, the Mann-Whitney U test was used.
RESULTS There was no direct linear correlation between the strength and proprioceptive correlation analysis at slow speed (60°/s) and fast speed (180°/s) in the racket-holding hand; At the slow speed (60°/s) and fast speed (180°/s), there was no correlation between muscle strength and proprioception in the non-racket-holding hand except for the internal rotation variable error (VE) and external rotation relative peak torque, which showed a moderate positive correlation (r = 0.477, P < 0.05), (r = 0.554, P < 0.05). The internal rotation’s constant error (CE) and VE were 1.06 ± 3.99 and 2.94 ± 2.16, respectively, for the racket-holding hand, and -3.36 ± 2.39 and 1.22 ± 0.93, respectively, for the non-racket-holding hand; the internal rotation’s CE, VE of the racket-holding hand was lower than that of the non-racket-holding hand, and there was a highly significant difference (P < 0.01).
CONCLUSION There was no correlation between muscle strength and proprioceptive function in the internal and external rotation of the racket-holding hand’s shoulder in elite Chinese male table tennis players. These results may be useful for interventions for shoulder injuries and for the inclusion of proprioceptive training in rehabilitation programs.
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Affiliation(s)
- Xue-Dong Shang
- Institute of Sport Medicine, National Research Institute of Sports Medicine, Beijing 100061, China
| | - En-Ming Zhang
- School of Sports Medicine and Rehabilitation, Beijing Sport University, Beijing 100084, China
| | - Zhen-Lei Chen
- School of Physical Education, Hubei University of Education, Wuhan 430205, Hubei Province, China
| | - Lei Zhang
- Graduate School, Shandong Sport University, Jinan 250102, Shandong Province, China
| | - Jing-Hua Qian
- School of Sports Medicine and Rehabilitation, Beijing Sport University, Beijing 100084, China
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Morini E, Gao D, Logan EM, Salani M, Krauson AJ, Chekuri A, Chen YT, Ragavendran A, Chakravarty P, Erdin S, Stortchevoi A, Svejstrup JQ, Talkowski ME, Slaugenhaupt SA. Developmental regulation of neuronal gene expression by Elongator complex protein 1 dosage. J Genet Genomics 2022; 49:654-665. [PMID: 34896608 PMCID: PMC9254147 DOI: 10.1016/j.jgg.2021.11.011] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2021] [Revised: 10/27/2021] [Accepted: 11/04/2021] [Indexed: 01/21/2023]
Abstract
Familial dysautonomia (FD), a hereditary sensory and autonomic neuropathy, is caused by a mutation in the Elongator complex protein 1 (ELP1) gene that leads to a tissue-specific reduction of ELP1 protein. Our work to generate a phenotypic mouse model for FD headed to the discovery that homozygous deletion of the mouse Elp1 gene leads to embryonic lethality prior to mid-gestation. Given that FD is caused by a reduction, not loss, of ELP1, we generated two new mouse models by introducing different copy numbers of the human FD ELP1 transgene into the Elp1 knockout mouse (Elp1-/-) and observed that human ELP1 expression rescues embryonic development in a dose-dependent manner. We then conducted a comprehensive transcriptome analysis in mouse embryos to identify genes and pathways whose expression correlates with the amount of ELP1. We found that ELP1 is essential for the expression of genes responsible for nervous system development. Further, gene length analysis of the differentially expressed genes showed that the loss of Elp1 mainly impacts the expression of long genes and that by gradually restoring Elongator, their expression is progressively rescued. Finally, through evaluation of co-expression modules, we identified gene sets with unique expression patterns that depended on ELP1 expression.
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Affiliation(s)
- Elisabetta Morini
- Center for Genomic Medicine, Massachusetts General Hospital Research Institute, Boston, MA, USA; Department of Neurology, Massachusetts General Hospital Research Institute and Harvard Medical School, Boston, MA, USA
| | - Dadi Gao
- Center for Genomic Medicine, Massachusetts General Hospital Research Institute, Boston, MA, USA; Department of Neurology, Massachusetts General Hospital Research Institute and Harvard Medical School, Boston, MA, USA; Program in Medical and Population Genetics and Stanley Center for Psychiatric Research, Broad Institute of Harvard and MIT, Cambridge, MA, USA
| | - Emily M Logan
- Center for Genomic Medicine, Massachusetts General Hospital Research Institute, Boston, MA, USA
| | - Monica Salani
- Center for Genomic Medicine, Massachusetts General Hospital Research Institute, Boston, MA, USA
| | - Aram J Krauson
- Center for Genomic Medicine, Massachusetts General Hospital Research Institute, Boston, MA, USA
| | - Anil Chekuri
- Center for Genomic Medicine, Massachusetts General Hospital Research Institute, Boston, MA, USA; Department of Neurology, Massachusetts General Hospital Research Institute and Harvard Medical School, Boston, MA, USA
| | - Yei-Tsung Chen
- Department of Life Sciences and Institute of Genome Sciences, National Yang Ming Chiao Tung University, Taiwan
| | - Ashok Ragavendran
- Center for Genomic Medicine, Massachusetts General Hospital Research Institute, Boston, MA, USA; Program in Medical and Population Genetics and Stanley Center for Psychiatric Research, Broad Institute of Harvard and MIT, Cambridge, MA, USA
| | - Probir Chakravarty
- Bioinformatics and Biostatistics, The Francis Crick Institute, London, UK
| | - Serkan Erdin
- Center for Genomic Medicine, Massachusetts General Hospital Research Institute, Boston, MA, USA; Program in Medical and Population Genetics and Stanley Center for Psychiatric Research, Broad Institute of Harvard and MIT, Cambridge, MA, USA
| | - Alexei Stortchevoi
- Center for Genomic Medicine, Massachusetts General Hospital Research Institute, Boston, MA, USA; Program in Medical and Population Genetics and Stanley Center for Psychiatric Research, Broad Institute of Harvard and MIT, Cambridge, MA, USA
| | - Jesper Q Svejstrup
- Mechanisms of Transcription Laboratory, The Francis Crick Institute, London, UK; Department of Cellular and Molecular Medicine, Panum Institute, University of Copenhagen, Copenhagen, Denmark
| | - Michael E Talkowski
- Center for Genomic Medicine, Massachusetts General Hospital Research Institute, Boston, MA, USA; Department of Neurology, Massachusetts General Hospital Research Institute and Harvard Medical School, Boston, MA, USA; Program in Medical and Population Genetics and Stanley Center for Psychiatric Research, Broad Institute of Harvard and MIT, Cambridge, MA, USA
| | - Susan A Slaugenhaupt
- Center for Genomic Medicine, Massachusetts General Hospital Research Institute, Boston, MA, USA; Department of Neurology, Massachusetts General Hospital Research Institute and Harvard Medical School, Boston, MA, USA.
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6
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Macefield VG. The roles of mechanoreceptors in muscle and skin in human proprioception. CURRENT OPINION IN PHYSIOLOGY 2021. [DOI: 10.1016/j.cophys.2021.03.003] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
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Longitudinal changes in the macula and optic nerve in familial dysautonomia. J Neurol 2020; 268:1402-1409. [PMID: 33180192 DOI: 10.1007/s00415-020-10298-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2020] [Revised: 10/29/2020] [Accepted: 11/01/2020] [Indexed: 10/23/2022]
Abstract
OBJECTIVE Familial Dysautonomia (FD) disease, lacks a useful biomarker for clinical monitoring. In this longitudinal study we characterized the structural changes in the macula, peripapillary and the optic nerve head (ONH) regions in subjects with FD. METHODS Data was consecutively collected from subjects attending the FD clinic between 2012 and 2019. All subjects were imaged with spectral-domain Optical Coherence Tomography (OCT). Global and sectoral measurements of mean retinal nerve fiber layer (RNFL) and macular ganglion cell and inner plexiform layer (GCIPL) thickness, and ONH parameters of rim area, average cup-to-disc (C:D) ratio, and cup volume were used for the analysis. The best fit models (linear, quadratic and broken stick linear model) were used to describe the longitudinal change in each of the parameters. RESULTS 91 subjects (149 eyes) with FD of ages 5-56 years were included in the analysis. The rate of change for average RNFL and average GCIPL thicknesses were significant before reaching a plateau at the age of 26.2 for RNFL and 24.8 for GCIPL (- 0.861 µm/year (95% CI - 1.026, - 0.693) and - 0.553 µm/year (95% CI - 0.645, - 0.461), respectively). Significant linear rate of progression was noted for all ONH parameters, except for a subset of subjects (24%), with no cupping that did not show progression in any of the ONH parameters. CONCLUSIONS The rapidly declining RNFL and GCIPL can explain the progressive visual impairment previously reported in these subjects. Among all structural parameters, ONH parameters might be most suitable for longitudinal follow-up, in eyes with a measurable cup.
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Norcliffe-Kaufmann L, Millar Vernetti P, Palma JA, Balgobin BJ, Kaufmann H. Afferent Baroreflex Dysfunction: Decreased or Excessive Signaling Results in Distinct Phenotypes. Semin Neurol 2020; 40:540-549. [PMID: 32906172 DOI: 10.1055/s-0040-1713892] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Head and neck tumors can affect afferent baroreceptor neurons and either interrupt or intermittently increase their signaling, causing blood pressure to become erratic. When the afferent fibers of the baroreflex are injured by surgery or radiotherapy or fail to develop as in familial dysautonomia, their sensory information is no longer present to regulate arterial blood pressure, resulting in afferent baroreflex failure. When the baroreflex afferents are abnormally activated, such as by paragangliomas in the neck, presumably by direct compression, they trigger acute hypotension and bradycardia and frequently syncope, by a mechanism similar to the carotid sinus syndrome. We describe our observations in a large series of 23 patients with afferent baroreflex dysfunction and the cardiovascular autonomic features that arise when the sensory baroreceptor neurons are injured or compressed. The management of afferent baroreceptor dysfunction is limited, but pharmacological strategies can mitigate blood pressure swings, improve symptoms, and may reduce hypertensive organ damage. Although rare, the prevalence of afferent baroreflex dysfunction appears to be increasing in middle-aged men due to human papillomavirus related oropharyngeal cancer.
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Affiliation(s)
| | | | - Jose-Alberto Palma
- Department of Neurology, New York University School of Medicine, New York, New York
| | - Bhumika J Balgobin
- Department of Neurology, New York University School of Medicine, New York, New York
| | - Horacio Kaufmann
- Department of Neurology, New York University School of Medicine, New York, New York
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Smith L, Norcliffe-Kaufmann L, Palma JA, Kaufmann H, Macefield VG. Elbow proprioception is normal in patients with a congenital absence of functional muscle spindles. J Physiol 2020; 598:3521-3529. [PMID: 32452029 DOI: 10.1113/jp279931] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2020] [Accepted: 05/13/2020] [Indexed: 01/24/2023] Open
Abstract
KEY POINTS Individuals with hereditary sensory and autonomic neuropathy type III (HSAN III), also known as Riley-Day syndrome or familial dysautonomia, do not have functional muscle spindle afferents but do have essentially normal cutaneous mechanoreceptors. Lack of muscle spindle feedback from the legs may account for the poor proprioception at the knee and the ataxic gait typical of HSAN III. Given that functional muscle spindle afferents are also absent in the upper limb, we assessed whether proprioception at the elbow was likewise compromised. Passive joint angle matching showed that proprioception was normal at the elbow, suggesting that individuals with HSAN III rely more on cutaneous afferents around the elbow. ABSTRACT Hereditary sensory and autonomic neuropathy type III (HSAN III) is a rare neurological condition that features a marked ataxic gait that progressively worsens over time. We have shown that functional muscle spindle afferents are absent in the upper and lower limbs in HSAN III, and we have argued that this may account for the ataxia. We recently used passive joint angle matching to demonstrate that proprioception of the knee joint is very poor in HSAN III but can be improved towards normal by application of elastic kinesiology tape across the knee joints, which we attribute to the presence of intact cutaneous mechanoreceptors. Here we assessed whether proprioception was equally compromised at the elbow joint, and whether it could be improved through taping. Proprioception at the elbow joint was assessed using passive joint angle matching in 12 HSAN III patients and 12 age-matched controls. There was no difference in absolute error, gradient or correlation coefficient of the relationship between joint angles of the reference and indicator arms. Unlike at the knee, taping did not improve elbow proprioception in either group. Clearly, the lack of muscle spindles compromised proprioception at the knee but not at the elbow, and we suggest that the HSAN III patients rely more on proprioceptive signals from the skin around the elbow.
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Affiliation(s)
- Lyndon Smith
- School of Medicine, Western Sydney University, Sydney, Australia
| | - Lucy Norcliffe-Kaufmann
- Dysautonomia Center, Department of Neurology, New York University School of Medicine, New York, USA
| | - Jose-Alberto Palma
- Dysautonomia Center, Department of Neurology, New York University School of Medicine, New York, USA
| | - Horacio Kaufmann
- Dysautonomia Center, Department of Neurology, New York University School of Medicine, New York, USA
| | - Vaughan G Macefield
- School of Medicine, Western Sydney University, Sydney, Australia.,Neuroscience Research Australia, Sydney, Australia.,Baker Heart and Diabetes Institute, Melbourne, Australia
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Lamers M, Reeves J, Alshamali R, Murnaghan C, Bent L. Can texture change joint position sense at the knee joint in those with poor joint position accuracy? Somatosens Mot Res 2019; 36:230-240. [PMID: 31509053 DOI: 10.1080/08990220.2019.1659765] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
Purpose: Skin contributes to joint position sense (JPS) at multiple joints. Altered cutaneous input at the foot can modulate gait and balance and kinesiology tape can enhance proprioception at the knee, but its effect may be dependent on existing capacity. The effect of texture at the knee, particularly in those with poor proprioception, is unknown. The aim of this study was to determine the effect of textured panels on JPS about the knee. Materials and methods: Eighteen healthy females were seated in an adjustable chair. Their left leg (target limb) moved passively from 65° to a target of flexion (115° or 90°) or extension (40°). Their right leg (matching limb) was passively moved towards this target angle and participants indicated when their limbs felt aligned. We tested three textured panels over the knee of the matching limb and two control conditions. The target limb maintained a control panel. Directional error, absolute error and variable error in matching between limbs were calculated. Results: On average textured panels over the knee increased JPS error compared to control pants for participants with poor JPS. These participants undershot the target at 90° of flexion significantly more with textured panels (-11° ± 3°) versus control (-7° ± 3°, p = 0.04). Conclusions: For participants with poor JPS accuracy, increased JPS error at 90° with a textured panel suggests these individuals utilised altered cutaneous information to adjust joint position. We propose increased error results from enhanced skin input at the knee leading to the perception of increased flexion.
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Affiliation(s)
- Meghan Lamers
- Department of Human Health and Nutritional Sciences, University of Guelph , Guelph , Canada
| | - Joanna Reeves
- Department of Human Health and Nutritional Sciences, University of Guelph , Guelph , Canada.,School of Health Sciences, University of Salford , Salford , UK
| | - Razan Alshamali
- Department of Human Health and Nutritional Sciences, University of Guelph , Guelph , Canada
| | | | - Leah Bent
- Department of Human Health and Nutritional Sciences, University of Guelph , Guelph , Canada
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ELP1 Splicing Correction Reverses Proprioceptive Sensory Loss in Familial Dysautonomia. Am J Hum Genet 2019; 104:638-650. [PMID: 30905397 DOI: 10.1016/j.ajhg.2019.02.009] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2018] [Accepted: 02/08/2019] [Indexed: 12/14/2022] Open
Abstract
Familial dysautonomia (FD) is a recessive neurodegenerative disease caused by a splice mutation in Elongator complex protein 1 (ELP1, also known as IKBKAP); this mutation leads to variable skipping of exon 20 and to a drastic reduction of ELP1 in the nervous system. Clinically, many of the debilitating aspects of the disease are related to a progressive loss of proprioception; this loss leads to severe gait ataxia, spinal deformities, and respiratory insufficiency due to neuromuscular incoordination. There is currently no effective treatment for FD, and the disease is ultimately fatal. The development of a drug that targets the underlying molecular defect provides hope that the drastic peripheral neurodegeneration characteristic of FD can be halted. We demonstrate herein that the FD mouse TgFD9;IkbkapΔ20/flox recapitulates the proprioceptive impairment observed in individuals with FD, and we provide the in vivo evidence that postnatal correction, promoted by the small molecule kinetin, of the mutant ELP1 splicing can rescue neurological phenotypes in FD. Daily administration of kinetin starting at birth improves sensory-motor coordination and prevents the onset of spinal abnormalities by stopping the loss of proprioceptive neurons. These phenotypic improvements correlate with increased amounts of full-length ELP1 mRNA and protein in multiple tissues, including in the peripheral nervous system (PNS). Our results show that postnatal correction of the underlying ELP1 splicing defect can rescue devastating disease phenotypes and is therefore a viable therapeutic approach for persons with FD.
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Smith LJ, Norcliffe-Kaufmann L, Palma JA, Kaufmann H, Macefield VG. Impaired sensorimotor control of the hand in congenital absence of functional muscle spindles. J Neurophysiol 2018; 120:2788-2795. [PMID: 30230986 DOI: 10.1152/jn.00528.2018] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Patients with hereditary sensory and autonomic neuropathy type III (HSAN III) exhibit marked ataxia, including gait disturbances. We recently showed that functional muscle spindle afferents in the leg, recorded via intraneural microelectrodes inserted into the peroneal nerve, are absent in HSAN III, although large-diameter cutaneous afferents are intact. Moreover, there is a tight correlation between loss of proprioceptive acuity at the knee and the severity of gait impairment. We tested the hypothesis that manual motor performance is also compromised in HSAN III, attributed to the predicted absence of muscle spindles in the intrinsic muscles of the hand. Manual performance in the Purdue pegboard task was assessed in 12 individuals with HSAN III and 11 age-matched healthy controls. The mean (±SD) pegboard score (number of pins inserted in 30 s) was 8.1 ± 1.9 and 8.6 ± 1.8 for the left and right hand, respectively, significantly lower than the scores for the controls (15.0 ± 1.3 and 16.0 ± 1.1; P < 0.0001). Performance was not improved after kinesiology tape was applied over the joints of the hand. In 5 patients we inserted a tungsten microelectrode into the ulnar nerve at the wrist. No spontaneous or stretch-evoked muscle afferent activity could be identified in any of the 11 fascicles supplying intrinsic muscles of the hand, whereas touch-evoked activity from low-threshold cutaneous mechanoreceptor afferents could readily be recorded from 4 cutaneous fascicles. We conclude that functional muscle spindles are absent in the short muscles of the hand and most likely absent in the long finger flexors and extensors, and that this largely accounts for the poor manual motor performance in HSAN III. NEW & NOTEWORTHY We describe the impaired manual motor performance in patients with hereditary sensory and autonomic neuropathy type III (Riley-Day syndrome), who exhibit congenital insensitivity to pain, poor proprioception, and marked gait ataxia. We show that functional muscle spindles are absent in the intrinsic muscles of the hand, which we argue contributes to their poor performance in a task involving the precision grip.
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Affiliation(s)
- Lyndon J Smith
- School of Medicine, Western Sydney University , Sydney , Australia
| | - Lucy Norcliffe-Kaufmann
- Dysautonomia Center, Department of Neurology, New York University School of Medicine , New York, New York
| | - Jose-Alberto Palma
- Dysautonomia Center, Department of Neurology, New York University School of Medicine , New York, New York
| | - Horacio Kaufmann
- Dysautonomia Center, Department of Neurology, New York University School of Medicine , New York, New York
| | - Vaughan G Macefield
- School of Medicine, Western Sydney University , Sydney , Australia.,Neuroscience Research Australia, Sydney , Australia.,Baker Heart & Diabetes Institute, Melbourne , Australia
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Macefield VG, Knellwolf TP. Functional properties of human muscle spindles. J Neurophysiol 2018; 120:452-467. [DOI: 10.1152/jn.00071.2018] [Citation(s) in RCA: 61] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Muscle spindles are ubiquitous encapsulated mechanoreceptors found in most mammalian muscles. There are two types of endings, primary and secondary, and both are sensitive to changes in muscle length and velocity, with the primary endings having a greater dynamic sensitivity. Unlike other mechanoreceptors in the somatosensory system, muscle spindles are unique in possessing motor innervation, via γ-motoneurons (fusimotor neurons), that control their sensitivity to stretch. Much of what we know about human muscles spindles comes from studying the behavior of their afferents via intraneural microelectrodes (microneurography) inserted into accessible peripheral nerves. We review the functional properties of human muscle spindles, comparing and contrasting with what we know about the functions of muscle spindles studied in experimental animals. As in the cat, many human muscle spindles possess a background discharge that is related to the degree of muscle stretch, but mean firing rates are much lower (~10 Hz). They can faithfully encode changes in muscle fascicle length in passive conditions, but higher level extraction of information is required by the central nervous system to measure changes in muscle length during muscle contraction. Moreover, although there is some evidence supporting independent control of human muscle spindles via fusimotor neurons, any effects are modest compared with the clearly independent control of fusimotor neurons observed in the cat.
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Affiliation(s)
- Vaughan G. Macefield
- School of Medicine, Western Sydney University, Sydney, Australia
- Neuroscience Research Institute, Sydney, Australia
- Baker Heart & Diabetes Institute, Melbourne, Australia
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Portnoy S, Maayan C, Tsenter J, Ofran Y, Goldman V, Hiller N, Karniel N, Schwartz I. Characteristics of ataxic gait in familial dysautonomia patients. PLoS One 2018; 13:e0196599. [PMID: 29698477 PMCID: PMC5919612 DOI: 10.1371/journal.pone.0196599] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2017] [Accepted: 04/16/2018] [Indexed: 11/19/2022] Open
Abstract
Introduction and objectives Progressive ataxic gait is a common symptom in individuals with Familial Dysautonomia (FD). At least 50% of adults with FD require assistance with walking. Our aims were to describe the medical condition of individuals with FD (ii) compare their gait characteristics to healthy individuals, and (iii) assess correlations between gait measures, presence of unstable gait pattern and frequency of falls. Methods Twelve subjects with FD (7 males, age 25.3±10.6 years) and 16 healthy participants (6 males, age 35.9±11.9 years) were recruited. Gait kinematics, gait symmetry, dynamic muscle activity, and foot deep vibration sensation were recorded. Results Ataxic gait degrees were: severe (6 out of 12), moderate (4 out of 12) and low (2 out of 12). The number of falls correlated with base width asymmetry. Crouch gait was noted in 3 out of 12 of the subjects. Conclusions In-depth quantitative gait analysis of individuals with FD revealed ataxic gait. The ataxic pattern might be a result of combined neurological deficiencies and osseous deformities. Increasing the base of support of patients with FD might increase the symmetry of the base width during gait and decrease the number of falls. Additionally, perturbation treatment and dynamic balance exercises may be recommended in order to improve compensatory strategies. Future investigation of this population should include quantification of osseous rotations of the lower limb in order to fully understand its effect on their gait pattern and falls.
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Affiliation(s)
- Sigal Portnoy
- Department of Physical Medicine and Rehabilitation, Hadassah Medical Center, Hebrew University Hadassah medical school, Jerusalem, Israel
- Department of Occupational Therapy, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
- * E-mail:
| | - Channa Maayan
- Familial Dysautonomia Center, Pediatric department, Hadassah Medical Center, Hebrew University Hadassah medical school, Jerusalem, Israel
| | - Jeanna Tsenter
- Department of Physical Medicine and Rehabilitation, Hadassah Medical Center, Hebrew University Hadassah medical school, Jerusalem, Israel
| | - Yonah Ofran
- Department of Physical Medicine and Rehabilitation, Hadassah Medical Center, Hebrew University Hadassah medical school, Jerusalem, Israel
| | - Vladimir Goldman
- Department of Orthopedic Surgery, Hadassah Medical Center, Hebrew University Hadassah medical school, Jerusalem, Israel
| | - Nurit Hiller
- Department of Radiology, Hadassah Medical Center, Hebrew University Hadassah medical school, Jerusalem, Israel
| | - Naama Karniel
- Department of Physical Medicine and Rehabilitation, Hadassah Medical Center, Hebrew University Hadassah medical school, Jerusalem, Israel
| | - Isabella Schwartz
- Department of Physical Medicine and Rehabilitation, Hadassah Medical Center, Hebrew University Hadassah medical school, Jerusalem, Israel
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Gutiérrez JV, Kaufmann H, Palma JA, Mendoza-Santiesteban C, Macefield VG, Norcliffe-Kaufmann L. Founder mutation in IKBKAP gene causes vestibular impairment in familial dysautonomia. Clin Neurophysiol 2017; 129:390-396. [PMID: 29289840 DOI: 10.1016/j.clinph.2017.11.010] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2017] [Revised: 11/10/2017] [Accepted: 11/16/2017] [Indexed: 12/16/2022]
Abstract
OBJECTIVE To assess vestibular function in patients with familial dysautonomia (FD), a hereditary sensory and autonomic neuropathy - caused by a mutation in the IKBKAP gene (c.2204 + 6 T>C) - and characterized by marked gait ataxia. METHODS Cervical and vestibular evoked myogenic potentials (cVEMPs and oVEMPs) were recorded from the sternocleidomastoid (SCM) and extraocular muscles in 14 homozygous patients, 2 heterozygous patients, and 15 healthy controls during percussion of the forehead. RESULTS cVEMP and oVEMP amplitudes were significantly lower, and peak latencies significantly delayed, in the FD patients. There were no differences in overall EMG during attempted maximal voluntary contractions of the SCM muscle, suggesting intact efferent function. The two heterozygotes with a minor haplotype missense (R696P) mutation in exon 19 of the IKBKAP gene had cVEMP responses less affected than the homozygous. CONCLUSIONS The founder mutation in the IKBKAP gene affects the development of vestibular afferent pathways, leading to attenuated cVEMPs. SIGNIFICANCE Vestibular abnormalities may contribute to the gait ataxia in FD.
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Affiliation(s)
- Joel V Gutiérrez
- Department of Clinical Neurophysiology, Cuban Institute of Neurology and Neurosurgery, La Habana, Cuba
| | - Horacio Kaufmann
- Department of Neurology, New York University School of Medicine, New York, NY, USA
| | - Jose-Alberto Palma
- Department of Neurology, New York University School of Medicine, New York, NY, USA
| | | | - Vaughan G Macefield
- College of Medicine, Mohammed Bin Rashid University of Medicine & Health Sciences, Dubai, United Arab Emirates
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Dietrich P, Dragatsis I. Familial Dysautonomia: Mechanisms and Models. Genet Mol Biol 2016; 39:497-514. [PMID: 27561110 PMCID: PMC5127153 DOI: 10.1590/1678-4685-gmb-2015-0335] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2015] [Accepted: 03/16/2016] [Indexed: 11/22/2022] Open
Abstract
Hereditary Sensory and Autonomic Neuropathies (HSANs) compose a heterogeneous group of genetic disorders characterized by sensory and autonomic dysfunctions. Familial Dysautonomia (FD), also known as HSAN III, is an autosomal recessive disorder that affects 1/3,600 live births in the Ashkenazi Jewish population. The major features of the disease are already present at birth and are attributed to abnormal development and progressive degeneration of the sensory and autonomic nervous systems. Despite clinical interventions, the disease is inevitably fatal. FD is caused by a point mutation in intron 20 of the IKBKAP gene that results in severe reduction in expression of IKAP, its encoded protein. In vitro and in vivo studies have shown that IKAP is involved in multiple intracellular processes, and suggest that failed target innervation and/or impaired neurotrophic retrograde transport are the primary causes of neuronal cell death in FD. However, FD is far more complex, and appears to affect several other organs and systems in addition to the peripheral nervous system. With the recent generation of mouse models that recapitulate the molecular and pathological features of the disease, it is now possible to further investigate the mechanisms underlying different aspects of the disorder, and to test novel therapeutic strategies.
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Affiliation(s)
- Paula Dietrich
- Department of Physiology, The University of Tennessee, Memphis, TN, USA
| | - Ioannis Dragatsis
- Department of Physiology, The University of Tennessee, Memphis, TN, USA
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Norcliffe-Kaufmann L, Slaugenhaupt SA, Kaufmann H. Familial dysautonomia: History, genotype, phenotype and translational research. Prog Neurobiol 2016; 152:131-148. [PMID: 27317387 DOI: 10.1016/j.pneurobio.2016.06.003] [Citation(s) in RCA: 75] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2016] [Revised: 06/10/2016] [Accepted: 06/11/2016] [Indexed: 01/30/2023]
Abstract
Familial dysautonomia (FD) is a rare neurological disorder caused by a splice mutation in the IKBKAP gene. The mutation arose in the 1500s within the small Jewish founder population in Eastern Europe and became prevalent during the period of rapid population expansion within the Pale of Settlement. The carrier rate is 1:32 in Jews descending from this region. The mutation results in a tissue-specific deficiency in IKAP, a protein involved in the development and survival of neurons. Patients homozygous for the mutations are born with multiple lesions affecting mostly sensory (afferent) fibers, which leads to widespread organ dysfunction and increased mortality. Neurodegenerative features of the disease include progressive optic atrophy and worsening gait ataxia. Here we review the progress made in the last decade to better understand the genotype and phenotype. We also discuss the challenges of conducting controlled clinical trials in this rare medically fragile population. Meanwhile, the search for better treatments as well as a neuroprotective agent is ongoing.
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Affiliation(s)
| | - Susan A Slaugenhaupt
- Center for Human Genetic Research, Massachusetts General Hospital Research Institute and Department of Neurology, Harvard Medical School, Boston, MA, USA
| | - Horacio Kaufmann
- Department of Neurology, New York University School of Medicine, New York, NY, USA.
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Macefield VG, Norcliffe-Kaufmann L, Goulding N, Palma JA, Fuente Mora C, Kaufmann H. Increasing cutaneous afferent feedback improves proprioceptive accuracy at the knee in patients with sensory ataxia. J Neurophysiol 2015; 115:711-6. [PMID: 26655817 DOI: 10.1152/jn.00148.2015] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2015] [Accepted: 11/30/2015] [Indexed: 11/22/2022] Open
Abstract
Hereditary sensory and autonomic neuropathy type III (HSAN III) features disturbed proprioception and a marked ataxic gait. We recently showed that joint angle matching error at the knee is positively correlated with the degree of ataxia. Using intraneural microelectrodes, we also documented that these patients lack functional muscle spindle afferents but have preserved large-diameter cutaneous afferents, suggesting that patients with better proprioception may be relying more on proprioceptive cues provided by tactile afferents. We tested the hypothesis that enhancing cutaneous sensory feedback by stretching the skin at the knee joint using unidirectional elasticity tape could improve proprioceptive accuracy in patients with a congenital absence of functional muscle spindles. Passive joint angle matching at the knee was used to assess proprioceptive accuracy in 25 patients with HSAN III and 9 age-matched control subjects, with and without taping. Angles of the reference and indicator knees were recorded with digital inclinometers and the absolute error, gradient, and correlation coefficient between the two sides calculated. Patients with HSAN III performed poorly on the joint angle matching test [mean matching error 8.0 ± 0.8° (±SE); controls 3.0 ± 0.3°]. Following application of tape bilaterally to the knee in an X-shaped pattern, proprioceptive performance improved significantly in the patients (mean error 5.4 ± 0.7°) but not in the controls (3.0 ± 0.2°). Across patients, but not controls, significant increases in gradient and correlation coefficient were also apparent following taping. We conclude that taping improves proprioception at the knee in HSAN III, presumably via enhanced sensory feedback from the skin.
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Affiliation(s)
| | - Lucy Norcliffe-Kaufmann
- Dysautonomia Center, Department of Neurology, New York University School of Medicine, New York, New York
| | - Niamh Goulding
- Dysautonomia Center, Department of Neurology, New York University School of Medicine, New York, New York
| | - Jose-Alberto Palma
- Dysautonomia Center, Department of Neurology, New York University School of Medicine, New York, New York
| | - Cristina Fuente Mora
- Dysautonomia Center, Department of Neurology, New York University School of Medicine, New York, New York
| | - Horacio Kaufmann
- Dysautonomia Center, Department of Neurology, New York University School of Medicine, New York, New York
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Brainstem reflexes in familial dysautonomia. Reply to "Evidence of brainstem dysfunction in patients with familial dysautonomia and carriers of the IKBKAP mutation". Clin Neurophysiol 2015; 127:1749-1750. [PMID: 26529998 DOI: 10.1016/j.clinph.2015.10.033] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2015] [Accepted: 10/08/2015] [Indexed: 11/21/2022]
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Palma JA, Norcliffe-Kaufmann L, Fuente-Mora C, Percival L, Mendoza-Santiesteban C, Kaufmann H. Current treatments in familial dysautonomia. Expert Opin Pharmacother 2014; 15:2653-71. [PMID: 25323828 PMCID: PMC4236240 DOI: 10.1517/14656566.2014.970530] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
INTRODUCTION Familial dysautonomia (FD) is a rare hereditary sensory and autonomic neuropathy (type III). The disease is caused by a point mutation in the IKBKAP gene that affects the splicing of the elongator-1 protein (ELP-1) (also known as IKAP). Patients have dramatic blood pressure instability due to baroreflex failure, chronic kidney disease, and impaired swallowing leading to recurrent aspiration pneumonia, which results in chronic lung disease. Diminished pain and temperature perception result in neuropathic joints and thermal injuries. Impaired proprioception leads to gait ataxia. Optic neuropathy and corneal opacities lead to progressive visual loss. AREAS COVERED This article reviews current therapeutic strategies for the symptomatic treatment of FD, as well as the potential of new gene-modifying agents. EXPERT OPINION Therapeutic focus on FD is centered on reducing the catecholamine surges caused by baroreflex failure. Managing neurogenic dysphagia with effective protection of the airway passages and prompt treatment of aspiration pneumonias is necessary to prevent respiratory failure. Sedative medications should be used cautiously due to the risk of respiratory depression. Non-invasive ventilation during sleep effectively manages apneas and prevents hypercapnia. Clinical trials of compounds that increase levels of IKAP (ELP-1) are underway and will determine whether they can reverse or slow disease progression.
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Affiliation(s)
- Jose-Alberto Palma
- New York University School of Medicine, Dysautonomia Center, Department of Neurology , 530 First Avenue, Suite 9Q New York, NY 10016 , USA +1 212 263 7225 ;
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Macefield VG, Norcliffe-Kaufmann L, Löken L, Axelrod FB, Kaufmann H. Disturbances in affective touch in hereditary sensory & autonomic neuropathy type III. Int J Psychophysiol 2014; 93:56-61. [PMID: 24726998 PMCID: PMC4078239 DOI: 10.1016/j.ijpsycho.2014.04.002] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2013] [Revised: 02/20/2014] [Accepted: 04/01/2014] [Indexed: 12/05/2022]
Abstract
Hereditary sensory and autonomic neuropathy type III (HSAN III, Riley–Day syndrome, Familial Dysautomia) is characterised by elevated thermal thresholds and an indifference to pain. Using microelectrode recordings we recently showed that these patients possess no functional stretch-sensitive mechanoreceptors in their muscles (muscle spindles), a feature that may explain their lack of stretch reflexes and ataxic gait, yet patients have apparently normal low-threshold cutaneous mechanoreceptors. The density of C-fibres in the skin is markedly reduced in patients with HSAN III, but it is not known whether the C-tactile afferents, a distinct type of low-threshold C fibre present in hairy skin that is sensitive to gentle stroking and has been implicated in the coding of pleasant touch are specifically affected in HSAN III patients. We addressed the relationship between C-tactile afferent function and pleasant touch perception in 15 patients with HSAN III and 15 age-matched control subjects. A soft make-up brush was used to apply stroking stimuli to the forearm and lateral aspect of the leg at five velocities: 0.3, 1, 3, 10 and 30 cm/s. As demonstrated previously, the control subjects rated the slowest and highest velocities as less pleasant than those applied at 1–10 cm/s, which fits with the optimal velocities for exciting C-tactile afferents. Conversely, for the patients, ratings of pleasantness did not fit the profile for C-tactile afferents. Patients either rated the higher velocities as more pleasant than the slow velocities, with the slowest velocities being rated unpleasant, or rated all velocities equally pleasant. We interpret this to reflect absent or reduced C-tactile afferent density in the skin of patients with HSAN III, who are likely using tactile cues (i.e. myelinated afferents) to rate pleasantness of stroking or are attributing pleasantness to this type of stimulus irrespective of velocity. C-tactile afferents in hairy skin are believed to mediate affective touch. They are sensitive to slow brushing stimuli, which are perceived as pleasant. It is not known whether C-tactile afferents are affected in HSAN III. Ratings of pleasantness were reduced in 15 HSAN III patients compared to controls. We suggest that the density of C-tactile afferents is reduced in HSAN III.
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Affiliation(s)
- Vaughan G Macefield
- School of Medicine, University of Western Sydney, Australia; Neuroscience Research Australia, Sydney, Australia.
| | | | - Line Löken
- Oxford Centre for Functional MRI of the Brain (FMRIB), University of Oxford, John Radcliffe Hospital, Oxford OX3 9DU, UK
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