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Migliorini F, Cocconi F, Schäfer L, Simeone F, Jeyaraman M, Maffulli N. Pharmacological management of secondary chronic spinal cord injury: a systematic review. Br Med Bull 2024; 151:49-68. [PMID: 39222962 DOI: 10.1093/bmb/ldae009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/10/2024] [Revised: 07/10/2024] [Accepted: 08/20/2024] [Indexed: 09/04/2024]
Abstract
INTRODUCTION Spinal cord injury (SCI) may bring lifelong consequences for affected patients and a high financial burden to the health care system. SOURCE OF DATA Published peer-reviewed scientific articles identified from EMBASE, Google Scholar, PubMed and Scopus. AREAS OF AGREEMENT Surgery and blood pressure management are the main targets in acute SCI to avoid secondary damage. AREAS OF CONTROVERSY The management of secondary chronic SCI is challenging, with unpredictable outcomes. GROWING POINTS Given the lack of consensus on pharmacological therapy for acute and secondary chronic SCI, the present study analyses the currently available drugs and treatment options to manage secondary chronic SCI. AREAS TIMELY FOR DEVELOPING RESEARCH Different approaches exist for the pharmacological management of secondary chronic SCI. One of the most investigated drugs, 4-aminopyridine, improves central motor conduction and shows improvement in neurological signs. Positive results in different areas have been observed in patients receiving the anti-spastic drugs tizanidine and baclofen or Granulocyte colony-stimulating factor. Growth hormone showed only minimal or no significant effects, and the therapy of secondary chronic SCI with riluzole has been poorly researched to date.
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Affiliation(s)
- Filippo Migliorini
- Department of Life Sciences, Health, and Health Professions, Link Campus University, Via del Casale di S. Pio V, 44, 00165 Rome, Italy
- Department of Orthopaedics and Trauma Surgery, Academic Hospital of Bolzano (SABES-ASDAA), via Lorenz Boelher 7, 39100 Bolzano, Italy
| | - Federico Cocconi
- Department of Orthopaedics and Trauma Surgery, Academic Hospital of Bolzano (SABES-ASDAA), via Lorenz Boelher 7, 39100 Bolzano, Italy
| | - Luise Schäfer
- Department of Life Sciences, Health, and Health Professions, Link Campus University, Via del Casale di S. Pio V, 44, 00165 Rome, Italy
| | - Francesco Simeone
- Department of Orthopaedics and Trauma Surgery, Academic Hospital of Bolzano (SABES-ASDAA), via Lorenz Boelher 7, 39100 Bolzano, Italy
| | - Madhan Jeyaraman
- Department of Orthopaedics, ACS Medical College and Hospital, Dr MGR Educational and Research Institute, Poonamallee High Rd, Velappanchavadi, Chennai 600077, Tamil Nadu, India
| | - Nicola Maffulli
- Department of Medicine and Psychology, University of Rome La Sapienza, via dei Marsi 78, 00185 Rome, Italy
- School of Pharmacy and Bioengineering, Keele University Faculty of Medicine, Hornbeam Building, Keele ST5 5BG, UK
- Queen Mary University of London, Barts and the London School of Medicine and Dentistry, Centre for Sports and Exercise Medicine, Mile End Hospital, 275 Bancroft Road, E1 4DG London, UK
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Eguibar JR, Cortes C, Hernandez VH, Lopez-Juarez A, Piazza V, Carmona D, Kleinert-Altamirano A, Morales-Campos B, Salceda E, Roncagliolo M. 4-aminopyridine improves evoked potentials and ambulation in the taiep rat: A model of hypomyelination with atrophy of basal ganglia and cerebellum. PLoS One 2024; 19:e0298208. [PMID: 38427650 PMCID: PMC10906851 DOI: 10.1371/journal.pone.0298208] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2023] [Accepted: 01/21/2024] [Indexed: 03/03/2024] Open
Abstract
The taiep rat is a tubulin mutant with an early hypomyelination followed by progressive demyelination of the central nervous system due to a point mutation in the Tubb4a gene. It shows clinical, radiological, and pathological signs like those of the human leukodystrophy hypomyelination with atrophy of the basal ganglia and cerebellum (H-ABC). Taiep rats had tremor, ataxia, immobility episodes, epilepsy, and paralysis; the acronym of these signs given the name to this autosomal recessive trait. The aim of this study was to analyze the characteristics of somatosensory evoked potentials (SSEPs) and motor evoked potentials (MEPs) in adult taiep rats and in a patient suffering from H-ABC. Additionally, we evaluated the effects of 4-aminopyridine (4-AP) on sensory responses and locomotion and finally, we compared myelin loss in the spinal cord of adult taiep and wild type (WT) rats using immunostaining. Our results showed delayed SSEPs in the upper and the absence of them in the lower extremities in a human patient. In taiep rats SSEPs had a delayed second negative evoked responses and were more susceptible to delayed responses with iterative stimulation with respect to WT. MEPs were produced by bipolar stimulation of the primary motor cortex generating a direct wave in WT rats followed by several indirect waves, but taiep rats had fused MEPs. Importantly, taiep SSEPs improved after systemic administration of 4-AP, a potassium channel blocker, and this drug induced an increase in the horizontal displacement measured in a novelty-induced locomotor test. In taiep subjects have a significant decrease in the immunostaining of myelin in the anterior and ventral funiculi of the lumbar spinal cord with respect to WT rats. In conclusion, evoked potentials are useful to evaluate myelin alterations in a leukodystrophy, which improved after systemic administration of 4-AP. Our results have a translational value because our findings have implications in future medical trials for H-ABC patients or with other leukodystrophies.
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Affiliation(s)
- Jose R. Eguibar
- Laboratorio de Neurofisiología de la Conducta y Control Motor, Instituto de Fisiología, Benemérita Universidad Autónoma de Puebla, Puebla, Pue, México
- Dirección General de Desarrollo Internacional, Benemérita Universidad Autónoma de Puebla, Puebla, Pue, México
| | - Carmen Cortes
- Laboratorio de Neurofisiología de la Conducta y Control Motor, Instituto de Fisiología, Benemérita Universidad Autónoma de Puebla, Puebla, Pue, México
| | - Victor H. Hernandez
- Departamento de Ingenierías Química, Electrónica y Biomédica, División de Ciencias e Ingenierías, Universidad de Guanajuato, León, Gto, México
| | - Alejandra Lopez-Juarez
- Departamento de Ingenierías Química, Electrónica y Biomédica, División de Ciencias e Ingenierías, Universidad de Guanajuato, León, Gto, México
| | - Valeria Piazza
- Centro de Investigaciones en Óptica, A.C., León, Gto, México
| | - Diego Carmona
- Departamento de Ingenierías Química, Electrónica y Biomédica, División de Ciencias e Ingenierías, Universidad de Guanajuato, León, Gto, México
- Centro de Investigaciones en Óptica, A.C., León, Gto, México
| | | | - Blanca Morales-Campos
- Departamento de Fisiología, Facultad de Medicina, Benemérita Universidad Autónoma de Puebla, Puebla, Puebla, Pue, México
| | - Emilio Salceda
- Revista Elementos, Benemérita Universidad Autónoma de Puebla, Puebla, Pue, México
| | - Manuel Roncagliolo
- Instituto de Fisiología, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso, Chile
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Santamaria AJ, Benavides FD, Saraiva PM, Anderson KD, Khan A, Levi AD, Dietrich WD, Guest JD. Neurophysiological Changes in the First Year After Cell Transplantation in Sub-acute Complete Paraplegia. Front Neurol 2021; 11:514181. [PMID: 33536992 PMCID: PMC7848788 DOI: 10.3389/fneur.2020.514181] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2019] [Accepted: 11/05/2020] [Indexed: 12/15/2022] Open
Abstract
Neurophysiological testing can provide quantitative information about motor, sensory, and autonomic system connectivity following spinal cord injury (SCI). The clinical examination may be insufficiently sensitive and specific to reveal evolving changes in neural circuits after severe injury. Neurophysiologic data may provide otherwise imperceptible circuit information that has rarely been acquired in biologics clinical trials in SCI. We reported a Phase 1 study of autologous purified Schwann cell suspension transplantation into the injury epicenter of participants with complete subacute thoracic SCI, observing no clinical improvements. Here, we report longitudinal electrophysiological assessments conducted during the trial. Six participants underwent neurophysiology screening pre-transplantation with three post-transplantation neurophysiological assessments, focused on the thoracoabdominal region and lower limbs, including MEPs, SSEPs, voluntarily triggered EMG, and changes in GSR. We found several notable signals not detectable by clinical exam. In all six participants, thoracoabdominal motor connectivity was detected below the clinically assigned neurological level defined by sensory preservation. Additionally, small voluntary activations of leg and foot muscles or positive lower extremity MEPs were detected in all participants. Voluntary EMG was most sensitive to detect leg motor function. The recorded MEP amplitudes and latencies indicated a more caudal thoracic level above which amplitude recovery over time was observed. In contrast, further below, amplitudes showed less improvement, and latencies were increased. Intercostal spasms observed with EMG may also indicate this thoracic “motor level.” Galvanic skin testing revealed autonomic dysfunction in the hands above the injury levels. As an open-label study, we can establish no clear link between these observations and cell transplantation. This neurophysiological characterization may be of value to detect therapeutic effects in future controlled studies.
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Affiliation(s)
- Andrea J Santamaria
- The Miami Project to Cure Paralysis, Miller School of Medicine, The University of Miami, Miami, FL, United States
| | - Francisco D Benavides
- The Miami Project to Cure Paralysis, Miller School of Medicine, The University of Miami, Miami, FL, United States
| | - Pedro M Saraiva
- The Miami Project to Cure Paralysis, Miller School of Medicine, The University of Miami, Miami, FL, United States
| | - Kimberly D Anderson
- The Miami Project to Cure Paralysis, Miller School of Medicine, The University of Miami, Miami, FL, United States.,The Department of Neurological Surgery, Miller School of Medicine, The University of Miami, Miami, FL, United States
| | - Aisha Khan
- The Miami Project to Cure Paralysis, Miller School of Medicine, The University of Miami, Miami, FL, United States.,Miller School of Medicine, The Interdisciplinary Stem Cell Institute, The University of Miami, Miami, FL, United States
| | - Allan D Levi
- The Miami Project to Cure Paralysis, Miller School of Medicine, The University of Miami, Miami, FL, United States.,The Department of Neurological Surgery, Miller School of Medicine, The University of Miami, Miami, FL, United States
| | - W Dalton Dietrich
- The Miami Project to Cure Paralysis, Miller School of Medicine, The University of Miami, Miami, FL, United States.,The Department of Neurological Surgery, Miller School of Medicine, The University of Miami, Miami, FL, United States
| | - James D Guest
- The Miami Project to Cure Paralysis, Miller School of Medicine, The University of Miami, Miami, FL, United States.,The Department of Neurological Surgery, Miller School of Medicine, The University of Miami, Miami, FL, United States
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Lonati D, Schicchi A, Crevani M, Buscaglia E, Scaravaggi G, Maida F, Cirronis M, Petrolini VM, Locatelli CA. Foodborne Botulism: Clinical Diagnosis and Medical Treatment. Toxins (Basel) 2020; 12:toxins12080509. [PMID: 32784744 PMCID: PMC7472133 DOI: 10.3390/toxins12080509] [Citation(s) in RCA: 37] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2020] [Revised: 08/04/2020] [Accepted: 08/06/2020] [Indexed: 12/14/2022] Open
Abstract
Botulinum neurotoxins (BoNTs) produced by Clostridia species are the most potent identified natural toxins. Classically, the toxic neurological syndrome is characterized by an (afebrile) acute symmetric descending flaccid paralysis. The most know typical clinical syndrome of botulism refers to the foodborne form. All different forms are characterized by the same symptoms, caused by toxin-induced neuromuscular paralysis. The diagnosis of botulism is essentially clinical, as well as the decision to apply the specific antidotal treatment. The role of the laboratory is mandatory to confirm the clinical suspicion in relation to regulatory agencies, to identify the BoNTs involved and the source of intoxication. The laboratory diagnosis of foodborne botulism is based on the detection of BoNTs in clinical specimens/food samples and the isolation of BoNT from stools. Foodborne botulism intoxication is often underdiagnosed; the initial symptoms can be confused with more common clinical conditions (i.e., stroke, myasthenia gravis, Guillain–Barré syndrome—Miller–Fisher variant, Eaton–Lambert syndrome, tick paralysis and shellfish or tetrodotoxin poisoning). The treatment includes procedures for decontamination, antidote administration and, when required, support of respiratory function; few differences are related to the different way of exposure.
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Affiliation(s)
- Davide Lonati
- Correspondence: ; Tel.: +39-0382-26261; Fax: +39-0382-24605
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Lewis MJ, Laber E, Olby NJ. Predictors of Response to 4-Aminopyridine in Chronic Canine Spinal Cord Injury. J Neurotrauma 2018; 36:1428-1434. [PMID: 30235970 DOI: 10.1089/neu.2018.5975] [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: 11/13/2022] Open
Abstract
4-Aminopyridine (4AP), a potassium channel antagonist, can improve hindlimb motor function in dogs with chronic thoracolumbar spinal cord injury (SCI); however, individual response is variable. We hypothesized that injury characteristics would differ between dogs that do and do not respond to 4AP. Our objective was to compare clinical, electrodiagnostic, gait, and imaging variables between dogs that do and do not respond to 4AP, to identify predictors of response. Thirty-four dogs with permanent deficits after acute thoracolumbar SCI were enrolled. Spasticity, motor and sensory evoked potentials (MEPs, SEPs), H-reflex, F-waves, gait scores, and magnetic resonance imaging (MRI) with diffusion tensor imaging (DTI) were evaluated at baseline and after 4AP administration. Baseline variables were assessed as predictors of response; response was defined as ≥1 point change in open field gait score. Variables were compared pre- and post-4AP to evaluate 4AP effects. Fifteen of 33 (45%) dogs were responders, 18/33 (55%) were non-responders and 1 was eliminated because of an adverse event. Pre-H-reflex threshold <1.2 mA predicted non-response; pre-H-reflex threshold >1.2 mA and Canine Spasticity Scale overall score <7 were predictive of response. All responders had translesional connections on DTI. MEPs were more common post-4AP than pre-4AP (10 vs. 6 dogs) and 4AP decreased H-reflex threshold and increased spasticity in responders. 4-AP impacts central conduction and motor neuron pool excitability in dogs with chronic SCI. Severity of spasticity and H-reflex threshold might allow prediction of response. Further exploration of electrodiagnostic and imaging characteristics might elucidate additional factors contributing to response or non-response.
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Affiliation(s)
- Melissa J Lewis
- 1 Veterinary Clinical Sciences, College of Veterinary Medicine, Purdue University, West Lafayette, Indiana
| | - Eric Laber
- 2 Department of Statistics, College of Sciences, North Carolina State University, Raleigh, North Carolina
| | - Natasha J Olby
- 3 Department of Clinical Sciences, College of Veterinary Medicine, and North Carolina State University, Raleigh, North Carolina.,4 Comparative Medicine Institute, North Carolina State University, Raleigh, North Carolina
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Guest J, Dietrich WD. Commentary Regarding the Recent Publication by Tabakow et al., "Functional Regeneration of Supraspinal Connections in a Patient with Transected Spinal Cord following Transplantation of Bulbar Olfactory Ensheathing Cells with Peripheral Nerve Bridging". J Neurotrauma 2015; 32:1176-8. [PMID: 25412291 DOI: 10.1089/neu.2014.3790] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Affiliation(s)
- James Guest
- Department of Neurological Surgery, The Miami Project to Cure Paralysis, University of Miami , Miami, Florida
| | - W Dalton Dietrich
- Department of Neurological Surgery, The Miami Project to Cure Paralysis, University of Miami , Miami, Florida
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Plemel JR, Keough MB, Duncan GJ, Sparling JS, Yong VW, Stys PK, Tetzlaff W. Remyelination after spinal cord injury: Is it a target for repair? Prog Neurobiol 2014; 117:54-72. [DOI: 10.1016/j.pneurobio.2014.02.006] [Citation(s) in RCA: 115] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2013] [Revised: 02/15/2014] [Accepted: 02/20/2014] [Indexed: 12/12/2022]
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OLBY NJ, SMITH DT, HUMPHREY J, SPINAPOLICE K, PARKE N, MEHTA PM, DISE D, PAPICH M. Pharmacokinetics of 4-aminopyridine derivatives in dogs. J Vet Pharmacol Ther 2009; 32:485-91. [DOI: 10.1111/j.1365-2885.2009.01072.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Oria M, Chatauret N, Raguer N, Córdoba J. A new method for measuring motor evoked potentials in the awake rat: effects of anesthetics. J Neurotrauma 2008; 25:266-75. [PMID: 18352840 DOI: 10.1089/neu.2007.0393] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The goal of this investigation was to develop a method to study the neurophysiological integrity of the central motor tract using motor evoked potentials in the awake rat and assess the effects of different anesthetics in this model. Rats were implanted with six subcutaneous electrodes (pediatric myocardial pacing leads) and one cranial screw. Motor evoked potentials of the hind limb were elicited after cranial and sciatic nerve stimulation. Experiments were repeated on different days during three weeks studying the effect of three different anesthetics (propofol, ketamine/xylazine, pentobarbital) at three different doses. Stimulation of motor evoked potentials in the awake rat was well tolerated with no effects on behavior. The electrodes could be kept chronically in place without signs of infection. The repeated recordings on different days showed high reproducibility after the fourth day following implantation of the electrodes. All three anesthetics induced an increase in the latency and a decrease in the amplitude of the motor evoked potentials which were dose dependent. Propofol (up to 1 mg/kg x min(1)) affected motor evoked potentials to a lesser extent than the other anesthetics. Based upon these findings, we believe that our approach provides a new method of chronically implanting electrodes in the rat to assess the neurophysiological function of the motor tract without the need of anesthetics. This model may prove useful in the investigation of various diseases that affect the motor pathways without the confounding effects of anesthesia.
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Affiliation(s)
- Marc Oria
- Servicio de Medicina Interna-Hepatología, Hospital Vall d'Hebron, Barcelona, Spain
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Abstract
Clinicians and scientists in the field of spinal cord injury research and medicine are poised to begin translating promising new experimental findings into treatments for people. Advances in experimental regeneration research have led to several transplantation strategies that promote axonal regrowth and partial functional recovery in animal models of injury. In this review, we summarize current knowledge regarding various invasive experimental treatments that have been or are now being applied clinically. Various questions about the timeliness, safety, and benefits of the procedures are under discussion within the spinal cord injury (SCI) research community. We also describe guidelines for carrying out optimal clinical trials and efforts to establish specific international guidelines to translate preclinical treatment strategies into clinical trials in SCI. The clinical trial process and the role that clinical professionals have in advising individuals regarding participation in experimental procedures also is discussed.
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Affiliation(s)
- Maria J Amador
- The Miami Project to Cure Paralysis, University of Miami Miller School of Medicine, Miami, FL, USA.
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Guest JD, Hiester ED, Bunge RP. Demyelination and Schwann cell responses adjacent to injury epicenter cavities following chronic human spinal cord injury. Exp Neurol 2005; 192:384-93. [PMID: 15755556 DOI: 10.1016/j.expneurol.2004.11.033] [Citation(s) in RCA: 219] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2004] [Revised: 11/18/2004] [Accepted: 11/30/2004] [Indexed: 02/02/2023]
Abstract
The natural history of post-traumatic demyelination and myelin repair in the human spinal cord is largely unknown and has remained a matter of speculation. A wealth of experimental studies indicate that mild to moderate contusive injuries to the mammalian spinal cord evolve into a cavity with a preserved rim of white matter in which a population of segmentally demyelinated axons persists. It is believed that such injured axons have abnormal conduction properties. Theoretically, such axons might show improved function if myelin repair occurred. Schwann cells can remyelinate axons affected by multiple sclerosis, but little evidence exists that such repair can occur spontaneously following traumatic human SCI. Therefore, it is important to determine if chronic demyelination is present following human spinal cord injury. There are no previous reports that have conclusively demonstrated demyelination in the human spinal cord following traumatic spinal cord injury using immunohistochemical techniques. Immunohistochemical methods were used to study the distribution of peripheral and central myelin proteins as well as axonal neurofilament at the injury epicenter in 13 postmortem chronically injured human spinal cords 1-22 years following injury. Of these seven could be assessed by our methods. We found that some axonal demyelination can be detected even a decade following human SCI and indirect evidence that invading Schwann cells contributed to restoration of myelin sheaths around some spinal axons.
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Affiliation(s)
- J D Guest
- Department of Neurological Surgery and the Miami Project to Cure Paralysis, University of Miami, Lois Pope LIFE Center, 1095 NW 14th Terrace, Miami, FL 33136, USA.
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DeForge D, Nymark J, Lemaire E, Gardner S, Hunt M, Martel L, Curran D, Barbeau H. Effect of 4-aminopyridine on gait in ambulatory spinal cord injuries: a double-blind, placebo-controlled, crossover trial. Spinal Cord 2004; 42:674-85. [PMID: 15356676 DOI: 10.1038/sj.sc.3101653] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
UNLABELLED Animal and human research have shown that the drug 4-aminopyridine (4-AP) may improve gait in spinal cord lesions by enhancing nerve transmission to affected muscles. STUDY DESIGN Prospective, randomized, double-blind, placebo-controlled, crossover trial. OBJECTIVES To determine the efficacy of 4-AP in improving lower limb muscle strength and biomechanical gait patterns of chronic spinal cord injuries (SCI). SETTING The Rehabilitation Centre (Ottawa, Canada). METHODS In all, 15 chronic, ambulatory SCI persons were randomized to an initial 2 weeks of 40 mg/day, oral medication of either placebo or immediate-release, 4-AP and subsequently crossed over to the alternate medication for the following 2 weeks. Evaluations were conducted at baseline (before starting 4-AP or placebo medication), 2 weeks, and 4 weeks. Measures included dynamometer lower limb isometric muscle force and biomechanical gait measures including temporal-spatial parameters, electromyographic activation patterns, joint kinematics and kinetics. Subjective impressions of the drug by the participants were obtained from an exit survey. RESULTS Despite some positive comments from subjects, statistical and clinical analyses showed no within-subject differences between placebo and 4-AP measures of lower limb muscle force and objective gait analyses (ANOVA statistic P>0.05). CONCLUSION Results demonstrated the importance of placebo-controlled trials and quantitative outcome measures for the evaluation of 4-AP aimed to enhance gait for chronic, ambulatory SCI persons. Energy expenditure measures and mood may relate more to subjective comments and is suggested for future investigations.
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Affiliation(s)
- D DeForge
- Division of Physical Medicine and Rehabilitation, University of Ottawa, Ottawa, Ontario, Canada
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Hayes KC, Potter PJ, Hsieh JT, Katz MA, Blight AR, Cohen R. Pharmacokinetics and safety of multiple oral doses of sustained-release 4-aminopyridine (fampridine-sr) in subjects with chronic, incomplete spinal cord injury 11A commercial party with a direct financial interest in the results of the research supporting this article has conferred or will confer a financial benefit on the author or 1 or more of the authors. Arch Phys Med Rehabil 2004; 85:29-34. [PMID: 14970964 DOI: 10.1016/s0003-9993(03)00651-8] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
OBJECTIVE To examine the pharmacokinetics and safety of sustained-release 4-aminopyridine (Fampridine-SR), a potassium channel blocker, in subjects with chronic, incomplete spinal cord injury (SCI). DESIGN Open-label. SETTING Clinical research unit in Ontario. PARTICIPANTS Sixteen neurologically stable subjects with chronic, incomplete SCI (American Spinal Injury Association Impairment Scale grade B, C, or D). INTERVENTION Oral administration of Fampridine-SR (25, 30, 35, 40, 50, 60 mg twice daily, each for 1 wk). MAIN OUTCOME MEASURES Steady-state pharmacokinetic parameters: maximum observed plasma concentration (Cmax), minimum observed plasma concentration (Cmin), average observed plasma concentration (Cav), area under the plasma concentration-time curve from 0 to 12 hours (AUC(0-12)), time to Cmax (tmax), plasma half-life (t(1/2)), apparent volume of distribution (Vd/F), and apparent total clearance (Cl/F). Safety assessments: physical examinations, vital sign measurements, clinical laboratory tests, electrocardiogram recordings, and adverse events. RESULTS Mean steady-state Cmax, Cmin, Cav, and AUC(0-12) increased over the entire Fampridine-SR dosage range and were dosage dependent up to 50 mg twice daily. Fampridine-SR had a mean tmax of 2.2 to 3.0 hours and a mean t(1/2) of 5.7 to 6.9 hours. Mean Vd/F (415.4-528.0 L) and Cl/F (51.4-57.7 L/h) were independent of dosage, as were mean tmax and t(1/2) across dosages. Adverse events were mild or moderate and were not dosage related. During the entire study period (17 wk), dizziness was the most frequently reported adverse event, followed by urinary tract infection, paresthesia, ataxia, and insomnia. CONCLUSION In subjects with chronic, incomplete SCI, Fampridine-SR was slowly absorbed and eliminated, which will allow Fampridine-SR to be administered in a convenient twice-daily manner. Fampridine-SR was well tolerated at dosages from 25 to 60 mg twice daily.
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Affiliation(s)
- Keith C Hayes
- The University of Western Ontario and Parkwood Hospital, London, Canada.
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Abstract
4-Aminopyridine (4-AP or fampridine) is a potassium channel-blocking agent that has been shown to restore conduction in focally demyelinated axons. A sustained-release matrix tablet form of 4-AP (fampridine-SR) is currently undergoing multicenter clinical trials in patients with multiple sclerosis or chronic spinal cord injury. This review describes the pharmacology and mechanisms of action of 4-AP, its pharmacokinetics in human subjects, and the outcomes of clinical trials employing either immediate-release or sustained-release formulations of the drug. The randomized clinical trials that have been completed to date indicate that K+ channel blockade may prove to be a useful strategy for ameliorating central conduction deficits due to demyelination. Diverse neurological gains have been reported for both motor and sensory domains. At the present time, however, the clinical trials have not provided sufficiently robust or definitive evidence of efficacy to gain regulatory approval for the symptomatic management of patients with either multiple sclerosis or spinal cord injury.
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Affiliation(s)
- Keith C Hayes
- Department of Physical Medicine & Rehabilitation, The University of Western Ontario, London, Ontario, Canada.
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15
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Hayes KC, Potter PJ, Hansebout RR, Bugaresti JM, Hsieh JTC, Nicosia S, Katz MA, Blight AR, Cohen R. Pharmacokinetic studies of single and multiple oral doses of fampridine-SR (sustained-release 4-aminopyridine) in patients with chronic spinal cord injury. Clin Neuropharmacol 2003; 26:185-92. [PMID: 12897638 DOI: 10.1097/00002826-200307000-00007] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Fampridine (4-aminopyridine) is a potassium channel blocking agent that restores conduction in demyelinated axons and improves neurologic function in patients with chronic spinal cord injury (SCI). Based on the pharmacokinetic profile of orally administered fampridine, multiple daily doses (4 or more) would need to be taken to sustain its therapeutic effects. Two studies were conducted to determine the pharmacokinetics and safety profile of an oral, sustained-release (SR) formulation of fampridine (fampridine-SR, 10-25 mg) administered as a single dose (n = 14) and twice daily for 1 week (n = 16) in patients with chronic, incomplete SCI. Mean plasma concentrations and area under the plasma concentration-time curve were proportional to the dose administered, whereas other pharmacokinetic parameters were independent of dose. Fampridine-SR was absorbed slowly (peak plasma concentration shortly after dosing, 2.6-3.7 hours) and eliminated (plasma half-life, 5.6-7.6 hours), and reached steady state after 4 days of twice-daily administration. Fampridine-SR was well tolerated, with only mild to moderate adverse events reported, and no serious adverse events. The extended plasma half-life of fampridine-SR allows convenient twice-daily dosing. Clinical trials designed to assess neurologic and functional improvement using fampridine-SR in patients with chronic SCI are currently underway.
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Affiliation(s)
- Keith C Hayes
- University of Western Ontario and Lawson Health Research Institute, London, Ontario, Canada.
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16
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Grijalva I, Guízar-Sahagún G, Castañeda-Hernández G, Mino D, Maldonado-Julián H, Vidal-Cantú G, Ibarra A, Serra O, Salgado-Ceballos H, Arenas-Hernández R. Efficacy and safety of 4-aminopyridine in patients with long-term spinal cord injury: a randomized, double-blind, placebo-controlled trial. Pharmacotherapy 2003; 23:823-34. [PMID: 12885095 DOI: 10.1592/phco.23.7.823.32731] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
OBJECTIVES To study the efficacy and safety of 4-aminopyridine (4-AP), and to document sensorimotor changes after discontinuation of the drug in patients with long-term spinal cord injury. DESIGN Randomized, double-blind, placebo-controlled trial. SETTING Clinical research unit. PATIENTS Twenty-seven patients with long-term spinal cord injury. INTERVENTION Patients were randomized to receive either oral 4-AP 5 mg/day, which was increased by 5 mg/week to a maximum dosage of 30 mg/day, or placebo for 12 weeks. They switched to the opposite treatment for the next 12 weeks. MEASUREMENTS AND MAIN RESULTS Twenty-five patients finished the study. The results from the first 12 weeks were used to test efficacy. Positive gains in motor function, sensation, and independence occurred more frequently in patients receiving 4-AP (69%) than those receiving placebo (46%). Significant functional improvement was also noted in those treated with 4-AP (chi2, p=0.042). When each evaluation scale was considered separately, significant improvement was seen only in motor function (4-AP 92% vs placebo 46%, Fisher exact test, p=0.03). Persistent effects of the drug were assessed at week 24 in the group that initially received 4-AP. A persistent, significant 4-AP effect was observed in evaluations of sensation and independence (67% and 83% of patients, respectively; Wilcoxon signed rank test, p=0.032 and 0.042, respectively). Fourteen (56%) patients had 26 adverse reactions. One moderate adverse reaction--posterior tibial artery vasospasm--and 25 mild adverse reactions, such as dry mouth, dizziness, nausea, gastritis, oral and peripheral paresthesia, resolved adequately. Six (24%) patients experienced transitory alterations of enzyme levels (alanine aminotransferase, aspartate aminotransferase, alkaline phosphatase, and creatine kinase) and thrombocytopenia. CONCLUSION Patients who received 4-AP showed significant improvement in motor function, and a persistent effect on sensation and independent function occurred. The drug is safe; however, after starting 4-AP therapy, patients must be carefully monitored for the possible occurrence of peripheral vasospasm.
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Affiliation(s)
- Israel Grijalva
- Research Medical Unit for Neurological Diseases, Specialties Hospital, Centro Médico Nacional Siglo XXI, Instituto Mexicano del Seguro Social, México City, México.
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17
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Hayes KC, Katz MA, Devane JG, Hsieh JTC, Wolfe DL, Potter PJ, Blight AR. Pharmacokinetics of an immediate-release oral formulation of Fampridine (4-aminopyridine) in normal subjects and patients with spinal cord injury. J Clin Pharmacol 2003; 43:379-85. [PMID: 12723458 DOI: 10.1177/0091270003251388] [Citation(s) in RCA: 69] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Plasma concentration profiles of the K+ channel-blocking compound Fampridine were obtained from (1) control subjects (n = 6) following oral administration of doses of 10, 15, 20, and 25 mg and (2) patients with spinal cord injury (SCI) (n = 11) following a single oral dose of 10 mg of an immediate-release formulation. Plasma concentrations were determined using a reversed-phase ion-pair high-performance liquid chromatography (HPLC) assay with ultraviolet light detection employing liquid extraction. The drug was rapidly absorbed with a tmax approximately 1 hour for both groups; tmax was independent of dose. Cmax and AUC0-infinity were linearly related to dose, and t 1/2 was 3 to 4 hours for both groups. There were no obvious differences in the (10-mg) plasma concentration profiles between control subjects and SCI patients. The drug was well tolerated, with only mild and transient side effects of light-headedness, dysesthesias, and dizziness.
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Affiliation(s)
- K C Hayes
- Department of Physical Medicine and Rehabilitation, University of Western Ontario, Program of Rehabilitation and Geriatric Care, Lawson Health Research Institute, St. Joseph's Health Care London, London, Ontario, Canada
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18
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Abstract
Most human spinal cord injuries involve contusions of the spinal cord. Many investigators have long used weight-drop contusion animal models to study the pathophysiology and genetic responses of spinal cord injury. All spinal cord injury therapies tested to date in clinical trial were validated in such models. In recent years, the trend has been towards use of rats for spinal cord injury studies. The MASCIS Impactor is a well-standardized rat spinal cord contusion model that produces very consistent graded spinal cord damage that linearly predicts 24-h lesion volumes, 6-week white matter sparing, and locomotor recovery in rats. All aspects of the model, including anesthesia for male and female rats, age rather than body weight criteria, and arterial blood gases were empirically selected to enhance the consistency of injury.
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Affiliation(s)
- Wise Young
- W.M. Keck Center for Collaborative Neuroscience, Rutgers State University of New Jersey, 604 Allison Rd., Piscataway, NJ 08854-8082, USA.
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19
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Hayes KC, Hull TCL, Delaney GA, Potter PJ, Sequeira KAJ, Campbell K, Popovich PG. Elevated serum titers of proinflammatory cytokines and CNS autoantibodies in patients with chronic spinal cord injury. J Neurotrauma 2002; 19:753-61. [PMID: 12165135 DOI: 10.1089/08977150260139129] [Citation(s) in RCA: 143] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
This study characterized the proinflammatory cytokines, interleukin-2 (IL-2) and tumor necrosis factor alpha (TNFalpha), the antiinflammatory cytokines, IL-4 and IL-10, autoantibodies specific for GM1 ganglioside (anti-GM1), IgG and IgM, and myelin-associated glycoprotein (anti-MAG), in the sera of infection-free, chronic (>12 months), traumatically injured SCI patients (n = 24). Healthy able-bodied subjects (n = 26) served as controls. The proinflammatory cytokines and anti-GM1 antibodies were of particular interest as they have been implicated in an autoimmune "channelopathy" component to central and peripheral conduction deficits in various chronic neuroinflammatory diseases. Antibody and cytokine titers were established using enzyme-linked immunosorbent assays (ELISA). The mean anti-GM(1) (IgM) titer value for the SCI group was significantly higher (p < 0.05) than controls. The SCI group also demonstrated significantly higher titers (p < 0.05) of IL-2 and TNF alpha than controls. No differences were found between the SCI group and control group mean levels of IL-4 or IL-10. Overall, the serum of 57% of SCI patients contained increased levels of autoantibodies or proinflammatory cytokines relative to control values. These results provide preliminary support for the hypothesis that chronic immunological activation in the periphery occurs in a subpopulation of chronic SCI patients. It remains to be established whether elevated serum titers of proinflammatory cytokines and autoantibodies against GM1 are beneficial to the patients or whether they are surrogate markers of a channelopathy that compounds the neurological impairment associated with traumatic axonopathy or myelinopathy.
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Affiliation(s)
- K C Hayes
- Department of Physical Medicine and Rehabilitation, University of Western Ontario, and Lawson Health Research Institute, St. Joseph's Health Care London, London, Ontario, Canada.
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20
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Edwards L, Nashmi R, Jones O, Backx P, Ackerley C, Becker L, Fehlings MG. Upregulation of Kv 1.4 protein and gene expression after chronic spinal cord injury. J Comp Neurol 2002; 443:154-67. [PMID: 11793353 DOI: 10.1002/cne.10115] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
After spinal cord injury (SCI), white matter tracts are characterized by demyelination and increased sensitivity to the K(+) channel blocker 4-aminopyridine (4-AP). These effects appear to contribute to neurological impairment after SCI, although the molecular changes in K(+) channel subunit expression remain poorly understood. We examined changes in gene expression of the 4-AP-sensitive voltage-gated K(+) channel Kv 1.4 after chronic SCI in the rat. Quantitative immunoblotting showed that Kv 1.4 protein was significantly increased at 6 weeks, but not at 1 week, after SCI in spinal cord white matter. Kv 1.4 was localized to astrocytes, oligodendrocytes, and oligodendrocyte progenitor cells but not to axons in both the normal and the injured spinal cord white matter. Because glial cells proliferate after SCI, we used immunogold electron microscopy to quantify Kv 1.4 protein in individual glial cells and found a sixfold increase of Kv 1.4 in cells of the oligodendrocyte lineage after chronic injury. Finally, quantitative in situ hybridization showed that Kv 1.4 mRNA was significantly upregulated in spinal cord white matter, but not gray matter, after SCI. In summary, we show that Kv 1.4 is expressed in glial cells and not in axons in the rat spinal cord white matter and that its expression is markedly increased in cells of the oligodendrocyte lineage after chronic SCI. Given that K(+) channels play a role in glial cell proliferation, cells exhibiting changes in Kv 1.4 expression may represent proliferating oligodendroglia in the chronically injured spinal cord.
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Affiliation(s)
- Lori Edwards
- Division of Neurosurgery, The Toronto Western Research Institute, University Health Network, University of Toronto, Toronto, Ontario, Canada M5T 2S8
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21
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Dumont RJ, Verma S, Okonkwo DO, Hurlbert RJ, Boulos PT, Ellegala DB, Dumont AS. Acute spinal cord injury, part II: contemporary pharmacotherapy. Clin Neuropharmacol 2001; 24:265-79. [PMID: 11586111 DOI: 10.1097/00002826-200109000-00003] [Citation(s) in RCA: 100] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Spinal cord injury (SCI) remains a common and devastating problem of modern society. Through an understanding of underlying pathophysiologic mechanisms involved in the evolution of SCI, treatments aimed at ameliorating neural damage may be developed. The possible pharmacologic treatments for acute spinal cord injury are herein reviewed. Myriad treatment modalities, including corticosteroids, 21-aminosteroids, opioid receptor antagonists, gangliosides, thyrotropin-releasing hormone (TRH) and TRH analogs, antioxidants and free radical scavengers, calcium channel blockers, magnesium replacement therapy, sodium channel blockers, N -methyl-D-aspartate receptor antagonists, alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid-kainate receptor antagonists, modulators of arachadonic acid metabolism, neurotrophic growth factors, serotonin antagonists, antibodies against inhibitors of axonal regeneration, potassium channel blockers (4-aminopyridine), paclitaxel, clenbuterol, progesterone, gabexate mesylate, activated protein C, caspase inhibitors, tacrolimus, antibodies against adhesion molecules, and other immunomodulatory therapy have been studied to date. Although most of these agents have shown promise, only one agent, methylprednisolone, has been shown to provide benefit in large clinical trials. Given these data, many individuals consider methylprednisolone to be the standard of care for the treatment of acute SCI. However, this has not been established definitively, and questions pertaining to methodology have emerged regarding the National Acute Spinal Cord Injury Study trials that provided these conclusions. Additionally, the clinical significance (in contrast to statistical significance) of recovery after methylprednisolone treatment is unclear and must be considered in light of the potential adverse effects of such treatment. This first decade of the new millennium, now touted as the Decade of the Spine, will hopefully witness the emergence of universal and efficacious pharmacologic therapy and ultimately a cure for SCI.
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Affiliation(s)
- R J Dumont
- Faculty of Medicine, University of British Columbia, Vancouver, British Columbia, Canada
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22
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Yu K, Rong W, Li J, Jia L, Yuan W, Yie X, Shi Z. Neurophysiological evidence of spared upper motor conduction fibers in clinically complete spinal cord injury: discomplete SCI in rats. J Neurol Sci 2001; 189:23-36. [PMID: 11535230 DOI: 10.1016/s0022-510x(01)00545-7] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
Motor evoked potentials (MEP) were recorded and characterized by epidural electrodes (scMEP) and extracellular microelectrodes (exMEP) on T(13) level from 10 normal rats and 40 rats with chronic spinal cord injury (SCI). The spinal cord of 40 anesthetized rats were injured with various severity (sham, 35, 70, and 100 g/cm impact injury) at T(8)-T(9) cord using Allen's drop model. The incline plane and Tarlov techniques were investigated to assess clinical neurological function. MEPs in the normal rats elicited by applying transcortical suprathreshold stimulation consisted of 3-4 early negative peaks (N(1), N(2), N(3), N(4)) followed by several late waves. The N(1) and N(2) peaks had their maximal amplitudes in the anterior and ventrolateral funiculus, respectively, irrespective of the polarity of stimulation, which indicated that these impulses were conducted mostly through the extrapyramidal pathways. The 100 g/cm impact injury or transection of the cord caused abolishment of the MEP signals distal to the lesion, whereas the 35 g/cm injury resulted in a latency shift and amplitude decrement of the MEP peaks. Out of 20 rats with 70 g/cm injuries, 18 showed clinically paraplegia. Among them, seven had neurophysiological evidence of residual conduction pathways through the injured cord segment, such as the presence of N(1) and N(2) peaks in scMEP or exMEP. After 4-aminopyridine (4-AP) administration (1 mg/kg), the amplitude of spared exMEP increased significantly and spread more widely. These results suggest that MEPs evoked by transcortical stimulation travel mostly in the extrapyramid tract. The present study provides further direct and objective electrophysiological evidences of spared functional axons after discomplete SCI, since many other studies on this field have achieved similar results previously. Furthermore, pharmaceutical treatment with 4-AP or other K(+) channel blocking agents proved to be a potential therapeutic strategy for patient with chronic SCI.
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Affiliation(s)
- K Yu
- Deparment of Orthopaedic Surgery, Changzheng Hospital, Feng Yang Road 415#, Shanghai 200003, People's Republic of China.
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23
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Wolfe DL, Hayes KC, Hsieh JT, Potter PJ. Effects of 4-aminopyridine on motor evoked potentials in patients with spinal cord injury: a double-blinded, placebo-controlled crossover trial. J Neurotrauma 2001; 18:757-71. [PMID: 11526982 DOI: 10.1089/089771501316919120] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
4-Aminopyridine (4-AP) is a potassium (K+) channel blocking agent that has been shown to reduce the latency and increase the amplitude of motor evoked potentials (MEPs) elicited with transcranial magnetic stimulation (TMS) in patients with chronic spinal cord injury (SCI). These effects on MEPs are thought to reflect enhanced conduction in long tract axons brought about by overcoming conduction deficits due to focal demyelination and/or by enhancing neuroneuronal transmission at one or more sites of the neuraxis. The present study was designed to obtain further evidence of reduced central motor conduction time (CMCT) and to determine whether MEPs could be recorded from paretic muscles in which they were not normally elicited. MEPs were elicited with TMS being delivered to subjects (n = 25) pre- and post-administration of 4-AP (10 mg capsule) or placebo. The principal finding was that 4-AP lowered the stimulation threshold, increased the amplitude and reduced the latency of MEPs in all muscles tested, including those that were unimpaired, but did not alter measures of the peripheral nervous system (i.e., M-wave, H-reflex, F-wave). These 4-AP-induced changes in MEPs were significantly greater than those seen with placebo (p < 0.05). The primary implication of these results is that a low dose of 4-AP (immediate-release formulation) appears to improve the impaired central motor conduction of some patients with incomplete SCI. This is most likely attributable to overcoming conduction deficits at the site of injury but may also involve an increase in cortical excitability.
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Affiliation(s)
- D L Wolfe
- Department of Physical Medicine and Rehabilitation, University of Western Ontario, London, Canada.
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24
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Nashmi R, Fehlings MG. Changes in axonal physiology and morphology after chronic compressive injury of the rat thoracic spinal cord. Neuroscience 2001; 104:235-51. [PMID: 11311546 DOI: 10.1016/s0306-4522(01)00009-4] [Citation(s) in RCA: 156] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
The spinal cord is rarely transected after spinal cord injury. Dysfunction of surviving axons, which traverse the site of spinal cord injury, appears to contribute to post-traumatic neurological deficits, although the underlying mechanisms remain unclear. The subpial rim frequently contains thinly myelinated axons which appear to conduct signals abnormally, although it is uncertain whether this truly reflects maladaptive alterations in conduction properties of injured axons during the chronic phase of spinal cord injury or whether this is merely the result of the selective survival of a subpopulation of axons. In the present study, we examined the changes in axonal conduction properties after chronic clip compression injury of the rat thoracic spinal cord, using the sucrose gap technique and quantitatively examined changes in the morphological and ultrastructural features of injured axonal fibers in order to clarify these issues. Chronically injured dorsal columns had a markedly reduced compound action potential amplitude (8.3% of control) and exhibited significantly reduced excitability. Other dysfunctional conduction properties of injured axons included a slower population conduction velocity, a longer refractory period and a greater degree of high-frequency conduction block at 200 Hz. Light microscopic and ultrastructural analysis showed numerous axons with abnormally thin myelin sheaths as well as unmyelinated axons in the injured spinal cord. The ventral column showed a reduced median axonal diameter and the lateral and dorsal columns showed increased median diameters, with evidence of abnormally large swollen axons. Plots of axonal diameter versus myelination ratio showed that post-injury, dorsal column axons of all diameters had thinner myelin sheaths. Noninjured dorsal column axons had a median myelination ratio (1.56) which was within the optimal range (1.43-1.67) for axonal conduction, whereas injured dorsal column axons had a median myelination ratio (1.33) below the optimal value. These data suggest that maladaptive alterations occur postinjury to myelin sheath thickness which reduce the efficiency of axonal signal transmission.In conclusion, chronically injured dorsal column axons show physiological evidence of dysfunction and morphological changes in axonal diameter and reduced myelination ratio. These maladaptive alterations to injured axons, including decrease in myelin thickness and the appearance of axonal swellings, contribute to the decreased excitability of chronically injured axons. These results further clarify the mechanisms underlying neurological dysfunction after chronic neurotrauma and have significant implications regarding approaches to augment neural repair and regeneration.
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Affiliation(s)
- R Nashmi
- Division of Neurosurgery and the University Health Network, The Toronto Western Hospital Research Institute, Institute of Medical Science, University of Toronto, M5T 2S8, Toronto, Canada
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25
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Segal JL, Hayes KC, Brunnemann SR, Hsieh JT, Potter PJ, Pathak MS, Tierney DS, Mason D. Absorption characteristics of sustained-release 4-aminopyridine (fampridine SR) in patients with chronic spinal cord injury. J Clin Pharmacol 2000; 40:402-9. [PMID: 10761168 DOI: 10.1177/00912700022008982] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Fampridine SR (4-aminopyridine) is a potassium channel-blocking drug currently being investigated for its therapeutic efficacy in ameliorating central conduction deficits due to demyelination in patients with spinal cord injury (SCI). The present open-label pharmacokinetic trial examined the absorption characteristics of a sustained-release form of the drug in 25 SCI subjects with chronic incomplete injuries. The overall group mean Cmax of 27.7 +/- 6.2 ng/mL occurred at a tmax of 3.4 +/- 1.4 hours. AUC0-12 was 210.5 +/- 49.5 ng/mL.h. For paraplegics, AUCtmax was 76.02 +/- 33.28 and for tetraplegics was significantly less at 51.25 +/- 20.36 (p = 0.037). A statistically significant difference in the initial rate and extent of absorption, but not in total 4-AP bioavailability over the 12-hour study period, was evident between tetraplegic patients, 0.60 +/- 0.23, and paraplegic patients, 0.39 +/- 0.14 (p = 0.02). There was a linear correlation (p < 0.05) between the neurological level of injury and Cmax/AUCtmax. These results confirm and extend previous observations of different rates of drug absorption among SCI patients with lesions above and below the sympathetic outflow (T6) and provide evidence of the absorption characteristics of this sustained-release form of 4-aminopyridine, which is helpful for optimal dosing.
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Affiliation(s)
- J L Segal
- Department of Veterans Affairs Medical Center, Long Beach, California 90822, USA
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26
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Boylan LS, Sackeim HA. Magnetoelectric brain stimulation in the assessment of brain physiology and pathophysiology. Clin Neurophysiol 2000; 111:504-12. [PMID: 10699414 DOI: 10.1016/s1388-2457(99)00280-1] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
OBJECTIVE To review findings from transcranial magnetic stimulation (TMS)-induced motor evoked potentials in normal subjects, in various neurological diseases and with pharmacologic manipulation. METHODS MEDLINE was searched to identify pertinent articles and articles referenced therein were also reviewed. RESULTS TMS is a safe and non-invasive technique which has been used widely in the study of corticospinal and corticocortical connectivity as well as in the assessment of basal ganglia disorders, diffuse diseases, and neuropharmacology. CONCLUSIONS TMS motor measures have utility in examination of brain structure and function within and beyond the corticospinal tract. These measures have both research and clinical applications.
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Affiliation(s)
- L S Boylan
- Department of Neurology, College of Physicians and Surgeons, Columbia University, New York, NY, USA.
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27
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Nashmi R, Jones OT, Fehlings MG. Abnormal axonal physiology is associated with altered expression and distribution of Kv1.1 and Kv1.2 K+ channels after chronic spinal cord injury. Eur J Neurosci 2000; 12:491-506. [PMID: 10712629 DOI: 10.1046/j.1460-9568.2000.00926.x] [Citation(s) in RCA: 72] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Dysfunction of surviving axons which traverse the site of spinal cord injury (SCI) has been linked to altered sensitivity to the K+ channel blocker 4-aminopyridine (4-AP) and appears to contribute to post-traumatic neurological deficits although the underlying mechanisms remain unclear. In this study, sucrose gap electrophysiology in isolated dorsal column strips, Western blotting and confocal immunofluorescence microscopy were used to identify the K+ channels associated with axonal dysfunction after chronic (6-8 weeks postinjury) clip compresssion SCI of the thoracic cord at T7 in rats. The K+ channel blockers 4-AP (200 microM, 1 mM and 10 mM) and alpha-dendrotoxin (alpha-DTX, 500 nM) resulted in a significant relative increase in the amplitude and area of compound action potentials (CAP) recorded from chronically injured dorsal column axons in comparison with control noninjured preparations. In contrast, TEA (10 mM) and CsCl (2 mM) had similar effects on injured and control spinal cord axons. Western blotting and quantitative immunofluorescence microscopy showed increased expression of Kv1.1 and Kv1.2 K+ channel proteins on spinal cord axons following injury. In addition, Kv1.1 and Kv1.2 showed a dispersed staining pattern along injured axons in contrast to a paired juxtaparanodal localization in uninjured spinal cord axons. Furthermore, labelled alpha-DTX colocalized with Kv1.1 and Kv1.2 along axons. These findings suggest a novel mechanism of axonal dysfunction after SCI whereby an increased 4-AP- and alpha-DTX-sensitive K+ conductance, mediated in part by increased Kv1.1 and Kv1.2 K+ channel expression, contributes to abnormal axonal physiology in surviving axons.
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Affiliation(s)
- R Nashmi
- Division of Neurosurgery and The Playfair Neuroscience Unit, The Toronto Western Hospital, University Health Network, University of Toronto, 399 Bathurst St., Toronto, M5T 2S8, Canada
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28
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Gruner JA, Yee AK. 4-Aminopyridine enhances motor evoked potentials following graded spinal cord compression injury in rats. Brain Res 1999; 816:446-56. [PMID: 9878868 DOI: 10.1016/s0006-8993(98)01184-6] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Although several experimental and clinical studies have demonstrated the ability of 4-aminopyridine (4-AP) to restore electrophysiological and/or behavioral function following chronic spinal cord injury, the mechanism by which this occurs remains unclear. Demonstration of efficacy in rat spinal cord injury has not been reported, evidently because even relatively mild spinal cord contusions that produce only minor permanent locomotor disturbances abolish hind limb myoelectric motor evoked potentials (mMEPs). In this study, mMEPs were recorded acutely 25 days following graded thoracic spinal cord compression in rats. mMEP amplitudes were significantly enhanced by a single, 2 mg/kg i.v. dose of 4-AP. mMEPs were increased in all rats showing some evoked responses initially, and also in some animals which had no responses prior to treatment. 4-AP was further found to increase the maximum following frequency of mMEPs in both normal and injured rats from about 0.1 Hz to between 1 and 10 Hz. These data suggest that 4-AP might act by enhancing synaptic efficacy, as well as enhancing conduction in spinal axons whose myelination has been rendered dysfunctional by trauma.
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Affiliation(s)
- J A Gruner
- Cephalon, Department of Experimental Pharmacology, 145 Brandywine Pkwy., West Chester, PA 19380-4245, USA.
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29
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Potter PJ, Hayes KC, Segal JL, Hsieh JT, Brunnemann SR, Delaney GA, Tierney DS, Mason D. Randomized double-blind crossover trial of fampridine-SR (sustained release 4-aminopyridine) in patients with incomplete spinal cord injury. J Neurotrauma 1998; 15:837-49. [PMID: 9814639 DOI: 10.1089/neu.1998.15.837] [Citation(s) in RCA: 71] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
A randomized double-blind dose-titration crossover trial of the safety and efficacy of oral fampridine-SR (sustained release 4-aminopyridine) was conducted on spinal cord injured (SCI) patients at two centers. Twenty-six patients (n = 26) with incomplete lesions completed the trial. These patients all had chronic (>2 years) and stable neurological deficits. They received fampridine-SR 12.5 and 17.5 mg b.i.d. over a 2-week treatment period, followed by a 1-week washout and 2 weeks of placebo, or vice versa. Patients reported significant benefit of fampridine-SR over placebo on patient satisfaction (McNemar's test, p2 < 0.05) and quality of life scores (p2 < 0.01). Sensory scores (p1 < 0.01), including both pin prick (p1 = 0.059) and light touch (p1 = 0.058), and motor scores (adjusted to reflect only paretic segments) (p1 < 0.01) all yielded evidence of benefit of fampridine-SR over placebo. The Ashworth scale of spasticity was significantly (p2 < 0.05) reduced when patients received fampridine-SR. There were no statistically significant benefits of the drug on measures of pain or bowel, bladder and sexual function, or functional independence. Side effects of lightheadedness and nausea were transient and trivial relative to efficacy, and approximately 30% of patients reported a wish to continue to use fampridine-SR. The clinical benefits most likely derive from the K+ channel blocking action of the drug. Potassium channel blockade enhances axonal conduction across demyelinated internodes and enhances neuroneuronal and neuromuscular transmission in preserved axons. These results provide the first evidence of therapeutic benefit of fampridine-SR in SCI patients.
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Affiliation(s)
- P J Potter
- Department of Physical Medicine and Rehabilitation, Parkwood Hospital, University of Western Ontario, London, Canada
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30
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Abstract
The recently published research data on the possible pathophysiology of acute spinal cord injury provide the basis of a number of exciting possibilities for its treatment. The present article reviews these lines of investigation. It focusses on methylprednisolone, which is the only effective proven therapy to limit secondary spinal cord injury known to date. In addition, the initial evaluation of patients with possible spinal cord trauma and airway management in patients with cervical spine injury are also discussed. Finally, the anaesthetic regimen in patients with these injuries is reviewed, showing that no anaesthetic agent or technique is superior to other anaesthetic methods.
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Affiliation(s)
- T Brüssel
- Klinik und Poliklinik für Anästhesiologie und operative Intensivmedizin der Westfälische Wilhelms-Universität Münster, Albert-Schweitzer-Strasse 33, D-48149 Münster, Germany
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31
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Abstract
Botulism is a paralyzing disease caused by the toxin of Clostridium botulinum. The toxin produces skeletal muscle paralysis by producing a presynaptic blockade to the release of acetylcholine. Recent studies have pinpointed the site of action of the several types of botulinum neurotoxin at the nerve terminal. Since the discovery of the toxin about 100 years ago, five clinical forms of botulism have been described: 1) classic or foodborne botulism; 2) wound botulism; 3) infant botulism; 4) hidden botulism; 5) inadvertent botulism. A clinical pattern of descending weakness is characteristic of all five forms. Almost all human cases of botulism are caused by one of three serotypes (A, B, or E). Classic and wound botulism were the only two forms known until the last quarter of this century. Wound botulism was rare until the past decade. Now there are increasing numbers of cases of wound botulism in injecting drug users. Infant botulism, first described in 1976, is now the most frequently reported form. In infant botulism spores of Clostridium botulinum are ingested and germinate in the intestinal tract. Hidden botulism, the adult variant of infant botulism, occurs in adult patients who usually have an abnormality of the intestinal tract that allows colonization by Clostridium botulinum. Inadvertent botulism is the most recent form to be described. It occurs in patients who have been treated with injections of botulinum toxin for dystonic and other movement disorders. Laboratory proof of botulism is established with the detection of toxin in the patient's serum, stool, or wound. The detection of Clostridium botulinum bacteria in the stool or wound should also be considered evidence of clinical botulism. Electrophysiologic studies can provide presumptive of botulism in patients with the clinical signs of botulism. Electrophysiologic testing can be especially helpful when bioassay studies are negative. The most consistent electrophysiologic abnormality is a small evoked muscle action potential in response to a single supramaximal nerve stimulus in a clinically affected muscle. Posttetanic facilitation can be found in some affected muscles. Single-fiber EMG studies typically reveal increased jitter and blocking, which become less marked following activation. The major treatment for severe botulism is advance medical and nursing supportive care with special attention to respiratory status.
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Affiliation(s)
- M Cherington
- Department of Neurology, University of Colorado School of Medicine, Denver, USA
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32
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Tator CH. Biology of neurological recovery and functional restoration after spinal cord injury. Neurosurgery 1998; 42:696-707; discussion 707-8. [PMID: 9574633 DOI: 10.1097/00006123-199804000-00007] [Citation(s) in RCA: 118] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
OBJECTIVE This article reviews the anatomic and pathophysiological bases for recovery of neurological function after experimental or clinical spinal cord injury (SCI). METHODS Current knowledge regarding the recovery of neurological function after experimental or clinical SCI was reviewed to determine the biological basis of neurological recovery. RESULTS There is a great propensity for recovery after clinical or experimental SCI. An examination of the anatomic basis of recovery indicates that there is a potential for both root and cord recovery, with the latter involving recovery of both gray and white matter of the cord. Resolution of acute injury events, such as hemorrhaging, and resolution of secondary pathophysiological processes, such as ischemia and excitotoxicity, can each account for recovery. The third recovery mechanism involves regrowth or regeneration of nervous tissue, resulting from either inherent or induced processes. CONCLUSION During the Decade of the Brain, there has been a profusion of very promising in vitro and in vivo studies that have shown enhanced neurological recovery after experimental or clinical SCI.
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Affiliation(s)
- C H Tator
- Division of Neurosurgery, Toronto Hospital and University of Toronto, Ontario, Canada
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