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Maamrah B, Pocsai K, Bayasgalan T, Csemer A, Pál B. KCNQ4 potassium channel subunit deletion leads to exaggerated acoustic startle reflex in mice. Neuroreport 2023; 34:232-237. [PMID: 36789839 PMCID: PMC10399928 DOI: 10.1097/wnr.0000000000001883] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2022] [Accepted: 01/06/2023] [Indexed: 02/16/2023]
Abstract
The potassium voltage-gated channel subfamily Q member 4 (KCNQ4) subunit forms channels responsible for M-current, a muscarine-sensitive potassium current regulating neuronal excitability. In contrast to other KCNQ subunits, its expression is restricted to the cochlear outer hair cells, the auditory brainstem and other brainstem nuclei in a great overlap with structures involved in startle reflex. We aimed to show whether startle reflexis affected by the loss of KCNQ4 subunit and whether these alterations are similar to the ones caused by brainstem hyperexcitability. Young adult KCNQ4 knockout mice and wild-type littermates, as well as mice expressing hM3D chemogenetic actuator in the pontine caudal nucleus and neurons innervating it were used for testing acoustic startle. The acoustic startle reflex was significantly increased in knockout mice compared with wild-type littermates. When mice expressing human M3 muscarinic (hM3D) in nuclei related to startle reflex were tested, a similar increase of the first acoustic startle amplitude and a strong habituation of the further responses was demonstrated. We found that the acoustic startle reflex is exaggerated and minimal habituation occurs in KCNQ4 knockout animals. These changes are distinct from the effects of the hyperexcitability of nuclei involved in startle. One can conclude that the exaggerated startle reflex found with the KCNQ4 subunit deletion is the consequence of both the cochlear damage and the changes in neuronal excitability of startle networks.
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Affiliation(s)
- Baneen Maamrah
- Department of Physiology, Faculty of Medicine, University of Debrecen
- Doctoral School of Molecular Medicine, University of Debrecen, Debrecen, Hungary
| | - Krisztina Pocsai
- Department of Physiology, Faculty of Medicine, University of Debrecen
| | - Tsogbadrakh Bayasgalan
- Department of Physiology, Faculty of Medicine, University of Debrecen
- Doctoral School of Molecular Medicine, University of Debrecen, Debrecen, Hungary
- Center for Molecular and Behavioral Neuroscience, Rutgers University, Newark, New Jersey, USA
| | - Andrea Csemer
- Department of Physiology, Faculty of Medicine, University of Debrecen
| | - Balázs Pál
- Department of Physiology, Faculty of Medicine, University of Debrecen
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van der Veen S, Caviness JN, Dreissen YE, Ganos C, Ibrahim A, Koelman JH, Stefani A, Tijssen MA. Myoclonus and other jerky movement disorders. Clin Neurophysiol Pract 2022; 7:285-316. [PMID: 36324989 PMCID: PMC9619152 DOI: 10.1016/j.cnp.2022.09.003] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2022] [Revised: 08/29/2022] [Accepted: 09/11/2022] [Indexed: 11/27/2022] Open
Abstract
Myoclonus and other jerky movements form a large heterogeneous group of disorders. Clinical neurophysiology studies can have an important contribution to support diagnosis but also to gain insight in the pathophysiology of different kind of jerks. This review focuses on myoclonus, tics, startle disorders, restless legs syndrome, and periodic leg movements during sleep. Myoclonus is defined as brief, shock-like movements, and subtypes can be classified based the anatomical origin. Both the clinical phenotype and the neurophysiological tests support this classification: cortical, cortical-subcortical, subcortical/non-segmental, segmental, peripheral, and functional jerks. The most important techniques used are polymyography and the combination of electromyography-electroencephalography focused on jerk-locked back-averaging, cortico-muscular coherence, and the Bereitschaftspotential. Clinically, the differential diagnosis of myoclonus includes tics, and this diagnosis is mainly based on the history with premonitory urges and the ability to suppress the tic. Electrophysiological tests are mainly applied in a research setting and include the Bereitschaftspotential, local field potentials, transcranial magnetic stimulation, and pre-pulse inhibition. Jerks due to a startling stimulus form the group of startle syndromes. This group includes disorders with an exaggerated startle reflex, such as hyperekplexia and stiff person syndrome, but also neuropsychiatric and stimulus-induced disorders. For these disorders polymyography combined with a startling stimulus can be useful to determine the pattern of muscle activation and thus the diagnosis. Assessment of symptoms in restless legs syndrome and periodic leg movements during sleep can be performed with different validated scoring criteria with the help of electromyography.
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Affiliation(s)
- Sterre van der Veen
- Department of Neurology, University of Groningen, University Medical Centre Groningen (UMCG), Groningen, The Netherlands,Expertise Centre Movement Disorders Groningen, University Medical Centre Groningen (UMCG), Groningen, The Netherlands
| | - John N. Caviness
- Department of Neurology, Mayo Clinic Arizona, Movement Neurophysiology Laboratory, Scottsdale, AZ, USA
| | - Yasmine E.M. Dreissen
- Department of Neurosurgery, Amsterdam University Medical Centers, Amsterdam, The Netherlands
| | - Christos Ganos
- Movement Disorders and Neuromodulation Unit, Department of Neurology, Charité University Medicine Berlin, Berlin, Germany
| | - Abubaker Ibrahim
- Department of Neurology, Medical University of Innsbruck, Innsbruck, Austria
| | - Johannes H.T.M. Koelman
- Department of Neurology and Clinical Neurophysiology, Amsterdam University Medical Centers, Amsterdam, The Netherlands
| | - Ambra Stefani
- Department of Neurology, Medical University of Innsbruck, Innsbruck, Austria
| | - Marina A.J. Tijssen
- Department of Neurology, University of Groningen, University Medical Centre Groningen (UMCG), Groningen, The Netherlands,Expertise Centre Movement Disorders Groningen, University Medical Centre Groningen (UMCG), Groningen, The Netherlands,Corresponding author at: Department of Neurology, University of Groningen, University Medical Centre Groningen (UMCG), PO Box 30.001, 9700 RB Groningen, The Netherlands.
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Moon D. Disorders of Movement due to Acquired and Traumatic Brain Injury. CURRENT PHYSICAL MEDICINE AND REHABILITATION REPORTS 2022; 10:311-323. [PMID: 36164499 PMCID: PMC9493170 DOI: 10.1007/s40141-022-00368-1] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/28/2022] [Indexed: 12/14/2022]
Abstract
Purpose of Review Both traumatic and acquired brain injury can result in diffuse multifocal injury affecting both the pyramidal and extrapyramidal tracts. Thus, these patients may exhibit signs of both upper motor neuron syndrome and movement disorder simultaneously which can further complicate diagnosis and management. We will be discussing movement disorders following acquired and traumatic brain injury. Recent Findings Multiple functions including speech, swallowing, posture, mobility, and activities of daily living can all be affected. Medical treatment and rehabilitation-based therapy can be especially challenging due to accompanying cognitive deficits and severity of the disorder which can involve multiple limbs in addition to muscles of the face and axial skeleton. Tremor and dystonia are the most reported movement disorders following traumatic brain injury. Dystonia and myoclonus are well documented following hypoxic ischemic brain injuries. Electrophysiological studies such as dynamic surface poly-electromyography can assist with identifying phenomenology, especially differentiating between jerk-like phenomenon and help guide further work up and management. Management with medications remains challenging due to potential adverse effects. Surgical interventions including stereotactic surgery, deep brain stimulation, and intrathecal baclofen pumps have been reported, but most of the evidence supporting them has been limited to primarily case reports except for post-traumatic tremor. Summary Brain injury can lead to motor disorders, movement disorders, visual (processing) deficits, and vestibular deficits which often coexist with cognitive deficits making it challenging to treat and rehabilitate these patients. Unfortunately, the evidence regarding the medical management and rehabilitation of brain injury patients with movement disorders is sparse and leaves much to be desired.
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Affiliation(s)
- Daniel Moon
- grid.421874.c0000 0001 0016 6543Moss Rehabilitation Hospital, Elkins Park, PA USA
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Maki Y, Kidokoro H, Okumura A, Yamamoto H, Nakata T, Fukasawa T, Kubota T, Kawaguchi M, Suzuki T, Tanaka M, Okai Y, Sakaguchi Y, Ohno A, Negoro T, Takahashi Y, Natsume J. Repetitive sleep starts: An important differential diagnosis of infantile spasms. Epilepsy Behav 2021; 121:108075. [PMID: 34077901 DOI: 10.1016/j.yebeh.2021.108075] [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] [Received: 02/18/2021] [Revised: 04/06/2021] [Accepted: 05/11/2021] [Indexed: 11/26/2022]
Abstract
OBJECTIVE Repetitive sleep starts (RSS) are clusters of nonepileptic, spasm-like movements occurring during sleep onset. However, their characteristics have yet to be defined. We conducted a clinicoelectroencephalographic study of children with RSS to clarify their detailed characteristics. METHODS To differentiate starts from epileptic spasms, we recruited children with brief "crescendo-decrescendo" muscle contractions that simultaneously involved the limbs and trunk without electroencephalogram changes, and that fulfilled the following criteria: (1) repeated occurrence (five or more) and (2) manifestation during sleep stage N1-N2. A total of nine children met these criteria. Their clinical information and video-electroencephalogram data were analyzed retrospectively. RESULTS The background conditions observed at onset of RSS were perinatal hypoxic-ischemic encephalopathy (n = 4), West syndrome of unknown etiology (n = 1), and traumatic brain injury (n = 1). The age at onset of RSS, the number of starts in a given RSS cluster, the interval between starts, and the duration of surface electromyogram activity were between 3 and 46 months, 5 and 547, <1 and 60 s, and 0.3 and 5.4 s, respectively. None of the median value of these parameters differed between children with and without corticospinal tract injury. During the median follow-up period of 33 months, RSS disappeared spontaneously in five. CONCLUSION This is the largest case series of RSS clarifying their clinicoelectroencephalographic characteristics reported to date. To avoid unnecessary antiepileptic therapies, clinicians should be aware of RSS and distinguish it from other disorders involving involuntary movements or seizures, especially epileptic spasms.
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Affiliation(s)
- Yuki Maki
- Department of Pediatrics, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Hiroyuki Kidokoro
- Department of Pediatrics, Nagoya University Graduate School of Medicine, Nagoya, Japan.
| | - Akihisa Okumura
- Department of Pediatrics, Aichi Medical University, Nagakute, Japan
| | - Hiroyuki Yamamoto
- Department of Pediatrics, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Tomohiko Nakata
- Department of Pediatrics, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | | | - Tetsuo Kubota
- Department of Pediatrics, Anjo Kosei Hospital, Anjo, Japan
| | - Masahiro Kawaguchi
- Department of Pediatrics, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Takeshi Suzuki
- Department of Pediatrics, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Masaharu Tanaka
- Department of Pediatrics, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Yu Okai
- Department of Pediatrics, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Yoko Sakaguchi
- Department of Pediatrics, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Atsuko Ohno
- Department of Pediatrics, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Tamiko Negoro
- Department of Pediatrics, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Yoshiyuki Takahashi
- Department of Pediatrics, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Jun Natsume
- Department of Pediatrics, Nagoya University Graduate School of Medicine, Nagoya, Japan; Department of Developmental Disability Medicine, Nagoya University Graduate School of Medicine, Nagoya, Japan
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Dreissen YEM, Koelman JHTM, Tijssen MAJ. The auditory startle response in relation to outcome in functional movement disorders. Parkinsonism Relat Disord 2021; 89:113-117. [PMID: 34274620 DOI: 10.1016/j.parkreldis.2021.07.012] [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: 03/06/2021] [Revised: 07/07/2021] [Accepted: 07/12/2021] [Indexed: 11/18/2022]
Abstract
BACKGROUND The auditory startle reflex (ASR) is enlarged in patients with functional movement disorders (FMD). OBJECTIVES To study whether the ASR relates to symptom reduction in FMD patients, who participated in a placebo controlled double blind treatment trial with Botulinum Neurotoxin (BoNT). METHODS Response to treatment in the BoNT study was assessed using the Clinical Global Impression - Improvement scale (CGI-I). The electromyography (EMG) muscle activity of 7 muscles following 110 dB tones was measured in 14 FMD patients before and after one-year treatment and compared to 11 matched controls. The early and a late (behaviorally affected) component of the ASR and the sympathetic skin response (SSR) were assessed. RESULTS 10 of 14 patients (71.4%) showed symptom improvement, which was believed to be mainly caused by placebo effects. The early total response probability of the ASR at baseline tended to be larger in patients compared to controls (p = 0.08), but normalized at follow-up (p = 0.84). The late total response probability was larger in patients vs. controls at baseline (p < 0.05), a trend that still was present at follow-up (p = 0.08). The SSR was higher in patients vs. controls at baseline (p < 0.01), and normalized at follow-up (p = 0.71). CONCLUSIONS On a group level 71.4% of the patients showed clinical symptom improvement after treatment. The early part of the ASR, most likely reflecting anxiety and hyperarousal, normalized in line with the clinical improvement. Interestingly, the augmented late component of the ASR remained enlarged suggesting persistent altered behavioral processing in functional patients despite motor improvement.
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Affiliation(s)
- Y E M Dreissen
- Department of Neurology and Clinical Neurophysiology, Amsterdam University Medical Center, University of Amsterdam, the Netherlands
| | - J H T M Koelman
- Department of Neurology and Clinical Neurophysiology, Amsterdam University Medical Center, University of Amsterdam, the Netherlands
| | - M A J Tijssen
- Department of Neurology, University Medical Centre Groningen, University Groningen, the Netherlands.
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Abstract
BACKGROUND In order to distinguish seizure mimics from seizures in children it is important to clarify the event duration, frequency, semiology, and any precipitating factors. METHODOLOGY This review provides a succinct and up-to-date overview aimed at general and subspecialty non-neurologist pediatric and adolescent health care providers to help guide a diagnostic approach when a child presents with paroxysmal events of unclear etiology. RESULTS In many cases, seizure mimics are consistently triggered by an event, location, or emotion, and often resolve with distraction or tactile stimulation. Suspicion should be raised for seizures when events occur out of deep sleep, there is a loss of consciousness with the event, movements are not suppressible, and there is a period of fatigue afterword (minutes to hours). Further, a past medical history of developmental delay (e.g. autism), developmental regression, or neurologic injury increases patients' risk for seizures. CONCLUSIONS Common seizure mimics are highlighted in the age group in which they are most prevalent.
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Affiliation(s)
- Rebecca S Stainman
- The Department of Neurology, NYU Langone Health, New York, NY, United States.
| | - Eric H Kossoff
- The Department of Neurology and The Department of Pediatrics, Johns Hopkins Medicine, 601N. Caroline St., Baltimore, MD 21287
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Journée SL, Journée HL, Berends HI, Reed SM, de Bruijn CM, Delesalle CJG. Comparison of Muscle MEPs From Transcranial Magnetic and Electrical Stimulation and Appearance of Reflexes in Horses. Front Neurosci 2020; 14:570372. [PMID: 33122992 PMCID: PMC7571265 DOI: 10.3389/fnins.2020.570372] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2020] [Accepted: 08/27/2020] [Indexed: 11/13/2022] Open
Abstract
Introduction Transcranial electrical (TES) and magnetic stimulation (TMS) are both used for assessment of the motor function of the spinal cord in horses. Muscular motor evoked potentials (mMEP) were compared intra-individually for both techniques in five healthy horses. mMEPs were measured twice at increasing stimulation intensity steps over the extensor carpi radialis (ECR), tibialis cranialis (TC), and caninus muscles. Significance was set at p < 0.05. To support the hypothesis that both techniques induce extracranially elicited mMEPs, literature was also reviewed. Results Both techniques show the presence of late mMEPs below the transcranial threshold appearing as extracranially elicited startle responses. The occurrence of these late mMEPs is especially important for interpretation of TMS tracings when coil misalignment can have an additional influence. Mean transcranial motor latency times (MLT; synaptic delays included) and conduction velocities (CV) of the ECR and TC were significantly different between both techniques: respectively, 4.2 and 5.5 ms (MLT TMS --MLT TES ), and -7.7 and -9.9 m/s (CV TMS -CV TES ). TMS and TES show intensity-dependent latency decreases of, respectively, -2.6 (ECR) and -2.7 ms (TC)/30% magnetic intensity and -2.6 (ECR) and -3.2 (TC) ms/30V. When compared to TMS, TES shows the lowest coefficients of variation and highest reproducibility and accuracy for MLTs. This is ascribed to the fact that TES activates a lower number of cascaded interneurons, allows for multipulse stimulation, has an absence of coil repositioning errors, and has less sensitivity for varying degrees of background muscle tonus. Real axonal conduction times and conduction velocities are most closely approximated by TES. Conclusion Both intracranial and extracranial mMEPs inevitably carry characteristics of brainstem reflexes. To avoid false interpretations, transcranial mMEPs can be identified by a stepwise latency shortening of 15-20 ms when exceeding the transcranial motor threshold at increasing stimulation intensities. A ring block around the vertex is advised to reduce interference by extracranial mMEPs. mMEPs reflect the functional integrity of the route along the brainstem nuclei, extrapyramidal motor tracts, propriospinal neurons, and motoneurons. The corticospinal tract appears subordinate in horses. TMS and TES are interchangeable for assessing the functional integrity of motor functions of the spinal cord. However, TES reveals significantly shorter MLTs, higher conduction velocities, and better reproducibility.
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Affiliation(s)
- Sanne Lotte Journée
- Equine Diagnostics, Wyns, Netherlands.,Department of Virology, Parasitology and Immunology, Research Group of Comparative Physiology, Faculty of Veterinary Medicine, Ghent University, Merelbeke, Belgium
| | - Henricus Louis Journée
- Department of Neurosurgery, University Medical Center Groningen, University of Groningen, Groningen, Netherlands.,Department of Orthopedics, University Medical Center Utrecht, Utrecht University, Utrecht, Netherlands.,Department of Orthopedics, University Medical Center Amsterdam, Amsterdam, Netherlands
| | - Hanneke Irene Berends
- Department of Orthopedics, University Medical Center Amsterdam, Amsterdam, Netherlands
| | - Steven Michael Reed
- Rood & Riddle Equine Hospital, Lexington, KY, United States.,M.H. Gluck Equine Research Center, Department of Veterinary Science, University of Kentucky, Lexington KY, United States
| | | | - Cathérine John Ghislaine Delesalle
- Department of Virology, Parasitology and Immunology, Research Group of Comparative Physiology, Faculty of Veterinary Medicine, Ghent University, Merelbeke, Belgium
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Age-Related Differences in Arm and Trunk Responses to First and Repeated Exposure to Laterally Induced Imbalances. Brain Sci 2020; 10:brainsci10090574. [PMID: 32825342 PMCID: PMC7564542 DOI: 10.3390/brainsci10090574] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2020] [Revised: 08/11/2020] [Accepted: 08/14/2020] [Indexed: 11/24/2022] Open
Abstract
The objective of this study was to examine age-related differences in arm and trunk responses during first and repeated step induced balance perturbations. Young and older adults received 10 trials of unpredictable lateral platform translations. Outcomes included maximum arm and trunk displacement within 1 s of perturbation and at first foot lift off (FFLO), arm and neck muscle activity as recorded using electromyography (EMG), initial step type, balance confidence, and percentage of harness-assisted trials. Compared to young adults, older adults demonstrated greater arm and trunk angular displacements during the first trial, which were present at FFLO and negatively associated with balance confidence. Unlike young adults, recovery steps in older adults were directed towards the fall with a narrowed base of support. Over repeated trials, rapid habituation of first-trial responses of bilateral arm and trunk displacement and EMG amplitude was demonstrated in young adults, but was absent or limited in older adults. Older adults also relied more on harness assistance during balance recovery. Exaggerated arm and trunk responses to sudden lateral balance perturbations in older adults appear to influence step type and balance recovery. Associations of these persistently amplified movements with an increased reliance on harness assistance suggest that training to reduce these deficits could have positive effects in older adults with and without neurological disorders.
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Saini AG, Pandey S. Hyperekplexia and other startle syndromes. J Neurol Sci 2020; 416:117051. [PMID: 32721683 DOI: 10.1016/j.jns.2020.117051] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2020] [Revised: 07/01/2020] [Accepted: 07/16/2020] [Indexed: 11/18/2022]
Abstract
Abnormal startle syndromes are classified into hyperekplexia, stimulus-induced, and neuropsychiatric startle syndromes. Hyperekplexia is attributed to a genetic, idiopathic, or symptomatic cause. Hereditary hyperekplexia is a treatable neurogenetic disorder. In patients with a hyperactive startle response, the first step is to characterize the extent and associations of 'response.' Secondary or symptomatic causes are particularly important in children, as they provide useful clinical clues to an underlying neurodevelopmental or neurodegenerative disorders. Particular attention should be given to any neonate or infant with generalized or episodic stiffness, drug-refractory seizures, recurrent apnea, stimulus-sensitive behavioral states, or sudden infant death syndrome. Eliciting a non-habituating head-retraction reflex to repeated nose tapping should be a part of routine examination of all new-borns. Vigevano maneuver should be taught to all families and health-care workers as an emergency rescue measure. The onset of excessive startle after infancy should direct investigations for an acquired cause such as brainstem injury, antibodies against glycine receptors, and neurodegeneration. Finally, one should not forget to evaluate unexplained cases of abnormal gait and frequent falls in adults for underlying undiagnosed startle syndromes. Oral clonazepam is an effective therapy besides behavioral and safety interventions for hereditary cases. The outcomes in genetic cases are good overall.
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Affiliation(s)
- Arushi Gahlot Saini
- Department of Pediatrics, Postgraduate Institute of Medical Education and Research, Chandigarh 160012, India
| | - Sanjay Pandey
- Department of Neurology, Govind Ballabh Pant Institute of Postgraduate medical education and research, JLN Marg, New Delhi 110002, India.
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Merchant SHI, Vial-Undurraga F, Leodori G, van Gerpen JA, Hallett M. Myoclonus: An Electrophysiological Diagnosis. Mov Disord Clin Pract 2020; 7:489-499. [PMID: 32626792 DOI: 10.1002/mdc3.12986] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2020] [Revised: 04/03/2020] [Accepted: 05/03/2020] [Indexed: 12/28/2022] Open
Abstract
Background Many different movement disorders have similar "jerk-like" phenomenology and can be misconstrued as myoclonus. Different types of myoclonus also share similar phenomenological characteristics that can be difficult to distinguish solely based on clinical exam. However, they have distinctive physiologic characteristics that can help refine categorization of jerk-like movements. Objectives In this review, we briefly summarize the clinical, physiologic, and pathophysiologic characteristics of different types of myoclonus. The methodology and technical considerations for the electrophysiologic assessment of jerk-like movements are reviewed. A simplistic pragmatic approach for the classification of myoclonus and other jerk-like movements based on objective electrophysiologic characteristics is proposed. Conclusions Clinical neurophysiology is an underutilized tool in the diagnosis and treatment of movement disorders. Various jerk-like movements have distinguishing physiologic characteristics, differentiated in the milliseconds range, which is beyond human capacity. We argue that the categorization of movement disorders as myoclonus can be refined based on objective physiology that can have important prognostic and therapeutic implications.
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Affiliation(s)
| | | | | | - Jay A van Gerpen
- Department of Neurology University of Alabama Huntsville Alabama USA
| | - Mark Hallett
- National Institute of Neurological Disorders and Stroke National Institutes of Health Bethesda Maryland USA
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Hakeem H, Khurshid R, Siddiqui F, Bhatti DE. Approach to exaggerated startle reflex: a case of hyperekplexia minor. BMJ Case Rep 2020; 13:13/4/e232370. [PMID: 32332042 DOI: 10.1136/bcr-2019-232370] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
Abstract
A broad set of conditions may present with an exaggerated startle reflex in clinics. This, combined with the overall rarity of these disorders, may pose diagnostic uncertainty in the mind of the treating physician. Herein, we report a case of a patient who presented to us with the complaint of exaggerated startle reflex and outline a simple approach towards characterisation of these disorders.
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Affiliation(s)
- Haris Hakeem
- Neurology, Aga Khan University Hospital, Karachi, Sindh, Pakistan
| | - Ramsha Khurshid
- Neurophysiology, Aga Khan University Hospital, Karachi, Sindh, Pakistan
| | - Fowzia Siddiqui
- Neurology, Aga Khan University Hospital, Karachi, Sindh, Pakistan
| | - Danish Ejaz Bhatti
- Neurological Sciences, University of Nebraska Medical Center, Omaha, Nebraska, USA
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12
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Mendez MF, Carr AR, Jimenez EE, Riedel BC, Thompson PM. Impaired Empathy Versus General Hypoemotionality in Frontotemporal Dementia. J Neuropsychiatry Clin Neurosci 2020; 31:378-385. [PMID: 31046591 DOI: 10.1176/appi.neuropsych.18090202] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
OBJECTIVE Impaired empathy is a diagnostic feature of behavioral variant frontotemporal dementia (bvFTD), but it is not clear whether it is caused by a primary impairment in empathy or by general emotional blunting. METHODS Patients with bvFTD who met criteria for loss of empathy (N=10) and patients with Alzheimer's disease (N=15) were assessed with a measure for empathy (Socioemotional Dysfunction Scale [SDS]) and a measure for general emotion (Scale for Emotional Blunting [SEB]). All patients underwent neuroimaging. Both patient groups and a healthy control group (N=18) were evaluated by using autonomic responses (skin conductance responses [SCR]) to pictures from the Internal Affective Picture System (IAPS) (presence or absence of empathy stimuli and high versus low emotion). RESULTS All participants reported understanding the content and others' perspectives on the empathy pictures; however, only patients with bvFTD showed impaired empathic behavior on the SDS, which persisted after adjusting for measures from the emotion scale (SEB). Patients with bvFTD had significantly lower SCR for all the IAPS stimuli, including for empathy pictures, which also persisted after adjusting for emotional content. On MRI analysis, SCR across groups significantly correlated with the volume of the dorsal anterior cingulate gyrus (dACC). CONCLUSIONS These results indicate that patients with bvFTD have decreased empathic behavior with or without emotional blunting, and they exhibit decreased psychophysiological responses to empathy stimuli, independent of general emotion. These preliminary findings suggest a specific impairment in emotional empathy, possibly related to impairment of the emotional appraisal role of the dACC.
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Affiliation(s)
- Mario F Mendez
- The Departments of Neurology, Psychiatry and Biobehavioral Sciences, and Medicine, Statistic Core, David Geffen School of Medicine, University of California at Los Angeles (Mendez, Jimenez); the VA Greater Los Angeles Healthcare System (Mendez, Carr, Jimenez); the Imaging Genetics Center, Mark and Mary Stevens Neuroimaging and Informatics Institute, University of Southern California, Los Angeles (Riedel, Thompson); and the Departments of Engineering, Neurology, Ophthalmology, Pediatrics, Psychiatry, and Radiology, University of Southern California, Los Angeles (Thompson)
| | - Andrew R Carr
- The Departments of Neurology, Psychiatry and Biobehavioral Sciences, and Medicine, Statistic Core, David Geffen School of Medicine, University of California at Los Angeles (Mendez, Jimenez); the VA Greater Los Angeles Healthcare System (Mendez, Carr, Jimenez); the Imaging Genetics Center, Mark and Mary Stevens Neuroimaging and Informatics Institute, University of Southern California, Los Angeles (Riedel, Thompson); and the Departments of Engineering, Neurology, Ophthalmology, Pediatrics, Psychiatry, and Radiology, University of Southern California, Los Angeles (Thompson)
| | - Elvira E Jimenez
- The Departments of Neurology, Psychiatry and Biobehavioral Sciences, and Medicine, Statistic Core, David Geffen School of Medicine, University of California at Los Angeles (Mendez, Jimenez); the VA Greater Los Angeles Healthcare System (Mendez, Carr, Jimenez); the Imaging Genetics Center, Mark and Mary Stevens Neuroimaging and Informatics Institute, University of Southern California, Los Angeles (Riedel, Thompson); and the Departments of Engineering, Neurology, Ophthalmology, Pediatrics, Psychiatry, and Radiology, University of Southern California, Los Angeles (Thompson)
| | - Brandalyn C Riedel
- The Departments of Neurology, Psychiatry and Biobehavioral Sciences, and Medicine, Statistic Core, David Geffen School of Medicine, University of California at Los Angeles (Mendez, Jimenez); the VA Greater Los Angeles Healthcare System (Mendez, Carr, Jimenez); the Imaging Genetics Center, Mark and Mary Stevens Neuroimaging and Informatics Institute, University of Southern California, Los Angeles (Riedel, Thompson); and the Departments of Engineering, Neurology, Ophthalmology, Pediatrics, Psychiatry, and Radiology, University of Southern California, Los Angeles (Thompson)
| | - Paul M Thompson
- The Departments of Neurology, Psychiatry and Biobehavioral Sciences, and Medicine, Statistic Core, David Geffen School of Medicine, University of California at Los Angeles (Mendez, Jimenez); the VA Greater Los Angeles Healthcare System (Mendez, Carr, Jimenez); the Imaging Genetics Center, Mark and Mary Stevens Neuroimaging and Informatics Institute, University of Southern California, Los Angeles (Riedel, Thompson); and the Departments of Engineering, Neurology, Ophthalmology, Pediatrics, Psychiatry, and Radiology, University of Southern California, Los Angeles (Thompson)
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Antonioni A, Peschi G, Granieri E. A Case of Hyperekplexia That Started From Childhood: Clinical Diagnosis With Negative Genetic Investigations. Front Neurol 2020; 11:10. [PMID: 32116999 PMCID: PMC7026473 DOI: 10.3389/fneur.2020.00010] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2019] [Accepted: 01/07/2020] [Indexed: 11/13/2022] Open
Abstract
Here, we report the case of a 63-year-old woman affected by abnormal, excessive, and involuntary reactions to harmless and unexpected sensory stimuli, compatible with the diagnosis of hyperekplexia. It is a pathology that involves the glycinergic system on a hereditary basis, and even if genetic proof compatible with the diagnosis is not present in this case, the fact that an aunt on her father's side suffered from the same disorders supports the clinical suspicion. From an early age, clinical history shows anomalous motor manifestations, initially framed as a form of focal epilepsy or ordinary disorders of the mood sphere, later excluded by the lack of effectiveness of a targeted therapy. Despite this, intellectual, psychological, and socio-emotional development was regular. The manifestations, present throughout childhood, adolescence, and early adulthood in moderate entity, worsened after the age of 50, perhaps due to hormonal changes. The presence of consequent anxiety and depression has compromised her quality of life, and in order to improve it, therapies were resorted, which, however, produced cognitive-attention deficits. No diagnostic exam has confirmed the diagnosis, although some scars in some brain areas involved in the control of reactions are elements favorable to this condition in genetically predisposed subjects. Therapies currently in use attenuate the motor symptomatology without resolving it and cause side effects in the psychological and cognitive sphere. In this case, we want to highlight the difficulty of diagnosing a very rare genetic condition, still not well-known, which presents symptoms easily mistaken for other more common diseases, because there are no specific clinical-diagnostic tools for the time being. In this particular case, we describe a female patient with an atypical onset age and negative genetic investigations compared with what is known in literature regarding this rare disorder. That is why it has been thought she was affected by epilepsy or anxiety-related disorders for several years.
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Affiliation(s)
- Annibale Antonioni
- Section of Neurology, Psychology and Psychiatry, Department of Biomedical and Specialty-Surgical Sciences, University of Ferrara, Ferrara, Italy
| | - Giovanni Peschi
- Department of Interventional, Pediatric and Diagnostic Radiology, Inselspital, University of Bern, Bern, Switzerland
| | - Enrico Granieri
- Section of Neurology, Psychology and Psychiatry, Department of Biomedical and Specialty-Surgical Sciences, University of Ferrara, Ferrara, Italy
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Merchant SH, Vial F, Leodori G, Fahn S, Pullman SL, Hallett M. A novel exaggerated "spino-bulbo-spinal like" reflex of lower brainstem origin. Parkinsonism Relat Disord 2018; 61:34-38. [PMID: 30316728 DOI: 10.1016/j.parkreldis.2018.10.007] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/19/2018] [Revised: 10/02/2018] [Accepted: 10/04/2018] [Indexed: 11/26/2022]
Abstract
BACKGROUND Many different oligosynaptic reflexes are known to originate in the lower brainstem which share phenomenological and neurophysiological similarities. OBJECTIVE To evaluate and discuss the differences and aberrancies among these reflexes, which are hard to discern clinically using neurophysiological investigations with the help of a case report. METHODS We describe the clinical and neurophysiological assessment of a young man who had a childhood history of opsoclonus-myoclonus syndrome with residual mild ataxia and myoclonic jerks in the distal extremities presenting with subacute onset total body jerks sensitive to sound and touch (in a limited dermatomal distribution), refractory to medications. RESULTS Based on clinical characteristics and insights gained from neurophysiological testing we could identify a novel reflex of caudal brainstem origin. CONCLUSIONS The reflex described is likely an exaggerated normal reflex, likely triggered by a dolichoectatic vertebral arterial compression and shares characteristics of different reflexes known to originate in caudal brainstem, which subserve distinctive roles in human postural control.
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Affiliation(s)
- Shabbir Hussain Merchant
- Human Motor Control Section, National Institute of Neurological Disorders and Stroke, National Institute of Health, Bethesda, MD, USA; Department of Neurology, Medical University of South Carolina, Charleston, SC, USA.
| | - Felipe Vial
- Human Motor Control Section, National Institute of Neurological Disorders and Stroke, National Institute of Health, Bethesda, MD, USA; Facultad de Medicina, Clínica Alemana Universidad del Desarrollo, Santiago, Chile
| | | | - Stanley Fahn
- Department of Neurology, College of Physicians and Surgeons, Columbia University, New York, NY, USA
| | - Seth L Pullman
- Department of Neurology, College of Physicians and Surgeons, Columbia University, New York, NY, USA
| | - Mark Hallett
- Human Motor Control Section, National Institute of Neurological Disorders and Stroke, National Institute of Health, Bethesda, MD, USA
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Abstract
The assessment, diagnosis, and management of orofacial pain (OFP) disorders is often a complex, multifactorial, and multidisciplinary process. Nociception leads to the perception of pain, causing the personal experience of suffering, which results in pain behavior. Many patients present with various comorbidities that may influence these conditions in a multitude of ways. The clinical presentation of OFP often includes biological, psychological, social, behavioral, and belief system components.
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Affiliation(s)
- Jeffrey A Crandall
- Surgery Health Care Service, University of Vermont Medical Center, 111 Colchester Avenue, Burlington, VT 05401, USA.
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16
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Dreissen YEM, Cath DC, Tijssen MAJ. Functional jerks, tics, and paroxysmal movement disorders. HANDBOOK OF CLINICAL NEUROLOGY 2016; 139:247-258. [PMID: 27719843 DOI: 10.1016/b978-0-12-801772-2.00021-7] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Functional jerks are among the most common functional movement disorders. The diagnosis of functional jerks is mainly based on neurologic examination revealing specific positive clinical signs. Differentiation from other jerky movements, such as tics, organic myoclonus, and primary paroxysmal dyskinesias, can be difficult. In support of a functional jerk are: acute onset in adulthood, precipitation by a physical event, variable, complex, and inconsistent phenomenology, suggestibility, distractibility, entrainment and a Bereitschaftspotential preceding the movement. Although functional jerks and tics share many similarities, characteristics differentiating tics from functional jerks are: urge preceding the tic, childhood onset, rostrocaudal development of the symptoms, a positive family history of tics, attention-deficit hyperactivity disorder or obsessive-compulsive symptoms, and response to dopamine antagonist medication. To differentiate functional jerks from organic myoclonus, localization of the movements can give direction. Further features in support of organic myoclonus include: insidious onset, simple and consistent phenomenology, and response to benzodiazepines or antiepileptic medication. Primary paroxysmal dyskinesias and functional jerks share a paroxysmal nature. Leading in the differentiation between the two are: a positive family history, in combination with video recordings revealing a consistent symptom pattern in primary paroxysmal dyskinesias. In this chapter functional jerks and their differential diagnoses will be discussed in terms of epidemiology, symptom characteristics, disease course, psychopathology, and supportive neurophysiologic tests.
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Affiliation(s)
- Y E M Dreissen
- Department of Neurology, University Medical Centre Groningen, Groningen, The Netherlands
| | - D C Cath
- Department of Clinical and Health Psychology, Utrecht University/Altrecht, Utrecht, The Netherlands
| | - M A J Tijssen
- Department of Neurology, University Medical Centre Groningen, Groningen, The Netherlands.
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17
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Behavioural changes in dogs treated with corticosteroids. Physiol Behav 2015; 151:609-16. [PMID: 26344646 DOI: 10.1016/j.physbeh.2015.08.041] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2015] [Revised: 08/30/2015] [Accepted: 08/31/2015] [Indexed: 11/22/2022]
Abstract
In human medicine, psychiatric side effects among patients on corticosteroid therapy are widely reported, but this appears to have been largely overlooked in the animal literature despite glucocorticoids being widely used in veterinary medicine. Therefore the aim of the current study was to identify possible psycho-behavioural changes in dogs treated with corticosteroids. Two different methodologies were used. Firstly, dog owners were asked to fill a 12 item questionnaire aimed at further validating the initial results of a previous survey relating to changes seen when their dog was receiving corticosteroid treatment. In a second study, a population of dogs undertook behavioural tests aimed at objectively identifying changes when receiving corticosteroid therapy. In the first study, a sample of owners whose dogs were receiving treatment for dermatological, orthopaedic or other conditions evaluated their dogs' behaviour on and off therapy, using a seven point scale. The survey was completed by 44 dog owners with dogs receiving treatment with a range of corticosteroid preparations (mainly prednisolone and methylprednisolone) and 54 dog owners with dogs receiving treatment with other drugs, mainly antibiotics and non-steroidal anti-inflammatory drugs. Dogs under corticosteroid treatment were reported to be significantly less playful, more nervous/restless, more fearful/less confident, more aggressive in the presence of food, more prone to barking, more prone to startle, more prone to reacting aggressively when disturbed, and more prone to avoiding people or unusual situations. In the second study, eleven “treatment” dogs were tested both before and during corticosteroid treatment with either methyl-prednisolone or prednisolone to assess their sensitivity to a potentially aversive sound stimulus. Eleven control dogs were also tested at the same time intervals in the same environment. Dogs were exposed to a brief dog growl while they explored bowls containing food and their behaviour was video recorded. Treatment dogs were found to investigate the area in the vicinity of the bowls for significantly less time and to eat significantly fewer pieces of food when on corticosteroids, compared to control dogs, after hearing the growl. These results provide the first empirical evidence of possible adverse psycho-behavioural side effects in a veterinary clinical setting following the use of corticosteroids, and suggest the need for concomitant behavioural advice when these drugs are used in general veterinary practise to avoid the risks associated with these changes.
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18
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Medan V, Preuss T. The Mauthner-cell circuit of fish as a model system for startle plasticity. ACTA ACUST UNITED AC 2014; 108:129-40. [PMID: 25106811 DOI: 10.1016/j.jphysparis.2014.07.006] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2014] [Revised: 07/18/2014] [Accepted: 07/21/2014] [Indexed: 11/30/2022]
Abstract
The Mauthner-cell (M-cell) system of teleost fish has a long history as an experimental model for addressing a wide range of neurobiological questions. Principles derived from studies on this system have contributed significantly to our understanding at multiple levels, from mechanisms of synaptic transmission and synaptic plasticity to the concepts of a decision neuron that initiates key aspects of the startle behavior. Here we will review recent work that focuses on the neurophysiological and neuropharmacological basis for modifications in the M-cell circuit. After summarizing the main excitatory and inhibitory inputs to the M-cell, we review experiments showing startle response modulation by temperature, social status, and sensory filtering. Although very different in nature, actions of these three sources of modulation converge in the M-cell network. Mechanisms of modulation include altering the excitability of the M-cell itself as well as changes in excitatory and inhibitor drive, highlighting the role of balanced excitation and inhibition for escape decisions. One of the most extensively studied forms of startle plasticity in vertebrates is prepulse inhibition (PPI), a sensorimotor gating phenomenon, which is impaired in several information processing disorders. Finally, we review recent work in the M-cell system which focuses on the cellular mechanisms of PPI and its modulation by serotonin and dopamine.
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Affiliation(s)
- Violeta Medan
- Dept. de Fisiología y Biología Molecular y Celular, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Intendente Guiraldes 2160, Buenos Aires 1428, Argentina; Instituto de Fisiología, Biología Molecular y Neurociencias, CONICET, Argentina.
| | - Thomas Preuss
- Psychology Dept. Hunter College, City University of New York, 695 Park Ave., New York, NY 10065, USA.
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Dinopoulos A, Stefanou MI, Attilakos A, Tsirouda M, Papaevangelou V. A case of startle epilepsy associated with IL1RAPL1 gene deletion. Pediatr Neurol 2014; 51:271-4. [PMID: 24950661 DOI: 10.1016/j.pediatrneurol.2014.04.011] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/29/2014] [Revised: 04/07/2014] [Accepted: 04/12/2014] [Indexed: 02/03/2023]
Abstract
BACKGROUND Startle epilepsy is a type of reflex epilepsy in which the seizures are mainly precipitated by unexpected sensory stimuli. PATIENT We present an 18-month-old boy with global developmental delay and multiple episodes of loss of tone after auditory cues. RESULTS The neurophysiologic study (video-electroencephalographic monitoring) revealed the epileptic nature of the stimulus-induced drop attacks, and the comparative genomic hybridization analysis revealed a microdeletion encompassing the interleukin-1 receptor accessory protein like 1 (IL1RAPL1) gene. The drop attacks were refractory to initial antiepileptic treatment, but they had a satisfactory response to a synthetic adrenocorticotropic hormone analogue. CONCLUSIONS The IL1RAPL1 gene is located on Xp21.2-p21.3 and codes a synaptic adhesion protein involved in neuronal differentiation and synapse localization, stabilization, and maturation. The coexistence of startle epilepsy and IL1RAPL1 gene deletion in this child may not be coincidental and suggests a possible involvement of IL1RAPL1 in the dysregulation of excitatory synapses and the pathogenesis of startle epilepsy.
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Affiliation(s)
- Argiris Dinopoulos
- Third Department of Paediatrics, Attiko University Hospital, University of Athens, Athens, Greece
| | - Maria-Ioanna Stefanou
- Department of Clinical Neuroscience, Institute of Psychiatry, King's College London, London, United Kingdom.
| | - Achilleas Attilakos
- Third Department of Paediatrics, Attiko University Hospital, University of Athens, Athens, Greece
| | - Maria Tsirouda
- Third Department of Paediatrics, Attiko University Hospital, University of Athens, Athens, Greece
| | - Vassiliki Papaevangelou
- Third Department of Paediatrics, Attiko University Hospital, University of Athens, Athens, Greece
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20
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Esposito M, Erro R, Edwards MJ, Cawley N, Choi D, Bhatia KP, Cordivari C. The pathophysiology of symptomatic propriospinal myoclonus. Mov Disord 2014; 29:1097-9. [PMID: 24976412 DOI: 10.1002/mds.25951] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2014] [Accepted: 05/07/2014] [Indexed: 11/11/2022] Open
Affiliation(s)
- Marcello Esposito
- Department of Neurosciences, University Federico II of Naples, Italy
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21
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Abstract
Many neurologic diseases cause discrete episodic impairment in contrast with progressive deterioration. The symptoms of these episodic disorders exhibit striking variety. Herein we review what is known of the phenotypes, genetics, and pathophysiology of episodic neurologic disorders. Of these, most are genetically complex, with unknown or polygenic inheritance. In contrast, a fascinating panoply of episodic disorders exhibit Mendelian inheritance. We classify episodic Mendelian disorders according to the primary neuroanatomical location affected: skeletal muscle, cardiac muscle, neuromuscular junction, peripheral nerve, or central nervous system (CNS). Most known Mendelian mutations alter genes that encode membrane-bound ion channels. These mutations cause ion channel dysfunction, which ultimately leads to altered membrane excitability as manifested by episodic disease. Other Mendelian disease genes encode proteins essential for ion channel trafficking or stability. These observations have cemented the channelopathy paradigm, in which episodic disorders are conceptualized as disorders of ion channels. However, we expand on this paradigm to propose that dysfunction at the synaptic and neuronal circuit levels may underlie some episodic neurologic entities.
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Affiliation(s)
- Jonathan F Russell
- Department of Neurology, Howard Hughes Medical Institute, School of Medicine, University of California-San Francisco, CA 94158, USA.
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23
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Facilitation and habituation of the startle reflex over the tonically active biceps brachii muscle contralateral to electrical stimuli. Neurosci Lett 2012; 527:6-10. [PMID: 22939942 DOI: 10.1016/j.neulet.2012.08.025] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2011] [Revised: 07/02/2012] [Accepted: 08/13/2012] [Indexed: 11/21/2022]
Abstract
The aim of the present investigation was to explore the impact of muscle contraction on startle reflex responses after electrical stimuli (single or trains of 3) and to study startle reflex habituation. The electromyogram was recorded over the tonically active biceps brachii muscle in 19 healthy subjects contralateral to electrical stimuli (9-12mA) that were delivered at 1.0 and 0.4Hz over the superficial radial nerve. The muscle contraction level was varied by loading weight on the subject's bent arm (0.0, 1.0 or 1.5kg). Furthermore, short term reflex habituation was investigated using 30 blocks of 5 subsequent stimuli. Startle response amplitudes gained significantly (p<0.05) after (i) train stimuli as compared with single stimuli, during (ii) high versus low levels of muscle contraction, and at (iii) 0.4Hz versus 1.0Hz stimuli. Startle reflex amplitudes decreased significantly by the influence of preceding stimuli (p<0.05). This study provides evidence that the startle reflex can be significantly influenced by weight load, i.e. by volitional influences. Startle reflex investigation over a contracted limb muscle results in a high probability of startle release and thereby improved detection of SR habituation following preceding stimuli.
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Maslovat D, Kennedy PM, Forgaard CJ, Chua R, Franks IM. The effects of prepulse inhibition timing on the startle reflex and reaction time. Neurosci Lett 2012; 513:243-7. [PMID: 22387455 DOI: 10.1016/j.neulet.2012.02.052] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2012] [Accepted: 02/14/2012] [Indexed: 10/28/2022]
Abstract
A loud acoustic stimulus has been shown to provoke a reflexive startle response and accelerate simple reaction times. However, an auditory prepulse presented in advance of a startling stimulus can reduce the effect of the startling stimulus. The current study examined the effect of the timing of the prepulse on startle-induced reaction times and the startle reflex. The task was to perform a 30° arm extension movement in response to a visual "go" stimulus. On selected trials, an auditory prepulse (80dB) was presented either 100ms, 500ms or 1000ms prior to the "go" signal. In addition, an auditory startling stimulus (124dB) was presented in conjunction with the "go" signal on some trials. Our results indicated that an auditory prepulse presented 100ms, and to a lesser extent 500ms, significantly decreased the amplitude of the startle reflex; however, the reaction time acceleration associated with the startling acoustic stimulus (SAS) was unaffected. The differential effect of the prepulse on the startle reflex and reaction time acceleration confirm different neural pathways for these effects while the differential effect of the prepulse on the control and startle RTs suggest different mechanisms for movement initiation.
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Affiliation(s)
- Dana Maslovat
- School of Kinesiology, University of British Columbia, Canada.
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25
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Rothwell J, Kofler M. Neurophysiology of the brainstem-structure and function of brainstem circuits. Clin Neurophysiol 2012; 123:2-3. [DOI: 10.1016/j.clinph.2011.10.008] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2011] [Accepted: 10/12/2011] [Indexed: 11/16/2022]
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