- Email: [email protected]
P624: Ultrasound evidence of concomitant traumatic nerve lesions far from the trauma site
S218
Abstracts of Poster Presentations / Clinical Neurophysiology 125, Supplement 1 (2014) S1–S339
P622 Lumbar spinal stenosis: an underestimated diagnosis? L. Teunissen 1 , F. Verheul 2 , S. Tromp 1 , J. Kelder 3 , M. van der Meulen 2 1 Clinical Neurophysiology, 2 Neurology, 3 St Antonius Hospital, Cardiology, St Antonius Hospital, Nieuwegein, Netherlands
Figure 2
nerves SNAPs were absent. Sural sensory responses are low in amplitude. She walked home unaided after three weeks stay in the hospital. Follow up EMGs were done nine weeks and 17 months later. Motor NCS were consistently normal in all four tests. SNAPs remained unobtainable from all upper limbs sensory nerves and peroneal nerves even after 17 months later. Sural sensory potentials remained low in amplitude. Clinically she feels back to normal however reflexes remained hyporeflexic. Conclusion: Ganglionopathy is a rare condition. Idiopathic, acute onset and monophasic course is presented. NCS obtained during acute illness revealed a different length dependent nature of neuropathy. Clinical recovery is not matched by routine NCS findings.
P621 A case of acquired neuromyotonia. Slow potassium channel dysfunction and the effect of voluntary contraction 1
2
3
1
M. Ballegaard , P. Born , M. Moldovan , C. Krarup 1 Rigshospitalet, Clinical Neurophysiology NF3063, Copenhagen, Denmark; 2 Rigshospitalet, Pediatrics, Copenhagen, Denmark; 3 University of Copenhagen, Neuroscience and Pharmacology, Copenhagen, Denmark Question: Prior nerve membrane excitability studies using QTRACK in acquired neuromyotonia were reported as normal. A 15y-old girl had a 6 month history of progressive generalized muscle cramps initiated by movements and preceded by flu-like illness. She had no family history. Methods: Electromyography was used to show myotonia. Nerve conduction studies were performed at rest and after a short and a long exercise test. QTRACK (Trond protocol) examined excitability properties of motor and sensory nerve membrane. Results: Electromyography (EMG) revealed 2-60 seconds 200Hz myotonic discharges. Recruitment pattern was normal. Motor unit potentials were normal without diplets, triplets or multiplets. Motor and sensory nerve conduction studies were normal and showed no decrement of the compound motor action potentials on 3 Hz repetitive stimuli. A short exercise test induced a 56% decrement. Subsequent 3Hz repetitive stimuli increased the decrement to 90%. A long exercise test was without decrement. A median nerve motor excitability study revealed an abnormal membrane accommodation (phase s2) after polarization and a reduced late subexcitability after a supramaximal stimulus. Sensory nerve excitability study was normal. Excitability studies in both parents and a sister and a brother were normal. She had no significant autoantibodies directed towards the voltage gated potassium channel. A test for intron point mutations in KCQN2 and KCQN3 was normal. We did not perform gene sequencing. A genetic test for congenital myotonia was normal. Conclusion: In this rare case of neuromyotonia both standard nerve conduction studies and QTRACK were abnormal. The excitability study supported the suspicion of an abnormal accommodation in this patient, and pointed to an abnormal function of the slow potassium channel responsible for the s2 phase. We suggest the abnormality in slowly inactivating potassium current as causative in a subgroup of patients with neuromyotonia.
Introduction: With overlapping symptoms and signs it can be difficult to differentiate lumbar spinal stenosis (LSS) from polyneuropathy (PNP). LSS is potentially treatable while PNP is often not. We assessed the prevalence of LSS in patients with symptoms of the legs and evaluated the value of history, neurological examination and electrophysiological investigation in recognising patients with LSS. Methods: Patients with sensory symptoms and/or weakness of both legs were included from June 2011 to March 2012. Patients with a history of typical neurogenic claudication or with symptoms of the hands were excluded. Every patient was seen by a neurologist and underwent nerve conduction studies, needle electromyography and an MRI of the lumbar spine. Patients were divided between a group with absolute LSS and a group without absolute LSS. Results: 59 patients were included, of whom 20 (34%) had an absolute LSS. Older age was a predictor for LSS (mean 75 versus 67 years, p=0.021). Patients with LSS significantly more often reported to experience cramps in the legs (6% versus 31%, p=0.049). Nerve conduction studies and needle electromyography could not differentiate patients with LSS from patients without LSS. Conclusions: LSS might be an underestimated diagnosis in patients with symptoms of the lower legs. Electrophysiological examination is not a potent tool to discriminate between PNP and LSS. It might warrant starting the work-up with an MRI of the lumbar spine to differentiate between PNP and LSS.
P623 Added value of the blink reflex in the evaluation of diabetic neuropathies E. Sisak County Hospital St. George, Neurology, Sfantul Gheorghe, Romania Question: Is there a correlation between the blink reflex (BR) and the electroneurography (ENG) in diabetic patients? Methods: The BR has been recorded in 35 diabetic patients, together with the ENG on motor and sensory peripheral nerves. The BR was obtained by stimulating separately the left and right supraorbital branch of the trigeminal nerve and recording each time the response in both orbicularis oculi muscles. The measures contained the latency of R1 and R2 responses, as well as the difference between sides. The ENG testing included the ulnar motor, median motor, radial sensitive, peroneal motor, tibial motor and sural nerves bilaterally. The following parameters were considered: distal latency, conduction velocity and amplitude of the CMAP and SNAP. Results: In the majority of patients (97%) both R1 and R2 latencies were prolonged with respect to normal values from the literature. These values did not correlate with the diabetes type, but showed a linear relationship with the time from the onset of the disease. The latency differences between sides were not statistically significant. ENG measures displayed the most prominent modifications in the sensory nerves of the inferior limbs, more axonal than demyelinating, then in the sensory nerves of the upper limbs, and finally the least affected being the motor nerves. The sural nerve was often unexcitable and in such instances it proved even more valuable to find an altered BR. The best correlation between BR and ENG was obtained when the R1 and R2 latency on the one hand, and the amplitude of the SNAP on the other hand were considered. Conclusions: Although a multitude of tests (mainly BR and ENG) allow a more reliable diagnosis, our study suggests that the BR can solely be a reliable determinant of a diabetic neuropathy in cases where the sural nerve cannot be excited.
P624 Ultrasound evidence of concomitant traumatic nerve lesions far from the trauma site C. Erra, P. De Franco, D. Coraci, G. Granata, I. Paolasso, L. Padua Università del Sacro Cuore, Roma, Roma, Italy Question: High-resolution ultrasound (US) of peripheral nerves is a valuable
Abstracts of Poster Presentations / Clinical Neurophysiology 125, Supplement 1 (2014) S1–S339
tool in the assessment of traumatic nerve lesions. Sometimes in traumatic nerve lesions multiple site damages can be observed. To identify cases of traumatic double site radial nerve involvement assessed through US. Methods: We retrospectively evaluated 36 patients admitted to our neurophysiology lab from January 2010 to March 2013 for traumatic radial nerve lesions following humeral fractures. All those patients underwent clinical, electrodiagnostic and sonographic evaluation. Results: In 14 patients a double site involvement of radial and posterior interosseous nerve was observed through US. Conclusions: Multiple site nerve lesions following a trauma can be suspected based on clinical evaluation (presence of non homogeneous motor or sensory deficit) but are difficult to demonstrate through electrodiagnostic assessment. US can help to detect unexpected nerve impairment and can help identify multiple site traumatic nerve lesions showing that they are often more frequent than we can diagnose with neurophysiology alone.
P625 Multimodal assessment of small fiber neuropathy: laser evoked potentials or skin biopsy? C. Créac’h 1,2 , J.-P. Camdessanche 3 , F. Robert 3 , J.-C. Antoine 3 , R. Peyron 1,2 , P. Convers 2,3 1 CHU Saint-Etienne, Pain Center, Saint-Etienne, France; 2 Inserm 1028-Central Integration of Pain Lab, Centre for Neurosciences, Lyon & Saint-Etienne, France; 3 CHU Saint-Etienne, Neurology, Saint-Etienne, France Question: Laser Evoked Potentials (LEPs) and Skin Biopsy (SB) are both considered as reliable methods for assessing a diagnosis of Small Fiber Neuropathy (SFN). The issue is whether these two methods are redundant or not. Methods: We selected 67 patients (42F, 25M; 54±14 years) with probable pure painful SFN including the feet. All of them had thermo-algesic hypesthesia (either observed clinically or confirmed by quantitative sensory testing). LEPs was considered as abnormal if N2P2 was abnormal on at least 2 areas out of the 8 explored (third cervical dermatoma, hands, thighs, feet). SB was considered as abnormal if the density of intra-epidermal nerve fibers (IENFD) was abnormal either on proximal (thighs) or distal (leg) areas. We compared the sensitivity of these techniques and explored clinical factors that may predict these results. Results: Only 58% of patients had abnormal IENFD while 79% of patients had abnormal LEPs. The concordancy between SB and LEPs was 55% on proximal areas and 51% on distal areas. There was 2.5 fold more patients with abnormal LEPs and normal SB than patients with normal LEPs and abnormal SB (23 vs 9 patients). These results were not explained by the length-dependent characteristics of SFN nor by the duration of pain evolution. Burning pain was the only clinical factor predicting abnormal SB (OR=4.1; p=0.024). Conclusions: The discrepancies between LEPs and SB may provide in part from differential lesions of A delta and C fibers. In practice we may recommend to record LEPs in a first approach in case of expected painful pure SFN.
P627 Is precautionary neurophysiological monitoring useful for beta-thalassemia patients? P. Nemtsas 1 , V. Perifanis 2 , E. Koutsouraki 1 , A. Orologas 1 , M. Arnaoutoglou 1 1 University General Hospital of Thessaloniki AHEPA, 1st Department of Neurology, Thessaloniki, Greece; 2 University General Hospital of Thessaloniki AHEPA, First Propedeutic Department of Internal Medicine, Thessaloniki, Greece The thalassemias are the most common single gene disorder in the world. Over the last years, a limited number of studies, mainly in children, have demonstrated a mild peripheral neuropathy in b-thalassemia patients. Chronic hypoxia, iron overload, desferrioxamine (DFO) neurotoxicity and bone marrow expansion are implicated, but sufficient explanatory evidence and biomarkers development is envisaged. We perform motor conduction studies of the median, ulnar, peroneal and tibial nerves, as well as sensory conduction studies of the median, ulnar, peroneal and sural nerves in adults. For the first time to our knowledge, we use extended EMG studies (brachioradialis, abductor digiti quinti (hand), extensors carpi radialis, anterior tibialis, quadriceps rectus femoris) to reveal and better analyze peripheral neuropathy in these patients. Our findings are correlated with the history, the laboratory findings and the medication followed. As life expectancy
S219
for b-thalassemia patients extends, we support the use of neurophysiologic monitoring in order to achieve the appropriate management and as a result a better life quality for this patient group.
P628 Electrophysiological data of DSMA1 patients in the Netherlands X. Stalpers 1 , A. Verrips 1 , B.-T. Poll-The 2 , J.M. Cobben 3 , I. Snoeck 4 , I. de Coo 5 , A. Brooks 6 , S. Bulk 7 , R. Gooskens 8 , A. Fock 9 , C. Verschuuren-Bemelmans 10 , R. Sinke 10 , M. de Visser 11 , H. Lemmink 10 1 Canisius Wilhelmina Hospital, Neurology, Nijmegen, Netherlands; 2 Emma Children’s Hospital, Academic Medical Center, Pediatric Neurology, Amsterdam, Netherlands; 3 Emma Children’s Hospital, Academic Medical Center, Pediatric Genetics, Amsterdam, Netherlands; 4 Juliana Children’s Hospital, Pediatrics, The Hague, Netherlands; 5 Erasmus Medical Center, Neurology, Rotterdam, Netherlands; 6 Erasmus Medical Center, Clinical Genetics, Rotterdam, Netherlands; 7 Wilhelmina Children’s Hospital, University Medical Center Utrecht, Medical Genetics, Utrecht, Netherlands; 8 Wilhelmina Children’s Hospital, University Medical Center Utrecht, Neurology, Utrecht, Netherlands; 9 University Medical Center Groningen, Neurology, Groningen, Netherlands; 10 University Medical Center Groningen, Genetics, Groningen, Netherlands; 11 Academic Medical Center, Neurology, Amsterdam, Netherlands Question: What are characteristic electrophysiological findings in DSMA1 patients? Background: Distal spinal muscular atrophy type 1 (DSMA1) is a rare disorder with distal muscle weakness, hypotonia and early respiratory difficulties as most striking symptoms. The pathophysiology is unknown. Some think the anterior horn cell is primarily affected, followed by degeneration of axons, others think it is vice versa. The former is supported by spinal cord autopsy data and findings in the animal model, the latter is supported by sural nerve biopsies and the early and severe changes in nerve conduction studies. Methods: We collected electrophysiological data of 10 Dutch DSMA1 patients. Results: Electrophysiological findings showed mostly reduced or absent compound muscle action potential (CMAP) and sensory nerve action potential (SNAP) amplitudes. Nerve conduction velocities are markedly reduced and could be in the demyelinating range. Distal motor latency (DML) was generally not in the demyelinating range, considering CMAP amplitudes below 1mV being less trustworthy. None of the patients showed evidence for conduction block. Electromyography could be normal or show spontaneous muscle fiber activity and reinnervation. Electrodiagnostic findings best fit an axonal neuropathy (Table 1, see p. S220). Conclusions: In these 10 Dutch DSMA1 patients, electrodiagnostic findings suggest a severe axonal neuropathy. Our findings make the anterior horn cell as the primary site of the disorder less likely. References: Diers A, Kaczinski M, Grohmann K, et al. The ultrastructure of peripheral nerve, motor-end plate and skeletal muscle in patients suffering from spinal muscular atrophy with respiratory distress type 1 (SMARD1). Acta Neuropathol 2005;110;289-97.
P629 A neurophysiological study of A-delta fibres in demyelinating and axonal polyneuropathies through cutaneous silent period recordings D. Lopergolo 1 , B. Isak 1,2 , M. Gabriele 1 , E. Onesti 1 , G. Tartaglia 1 , A. Biasiotta 1 , S. La Cesa 1 , G. Di Stefano 1 , A. Truini 1 , M. Inghilleri 1 1 “Sapienza” University of Rome, Department of Neurology and Psychiatry, Rome, Italy; 2 Marmara University, Istanbul, Turkey Introduction: Cutaneous silent period (CSP) is a brief pause in voluntary muscle contraction following noxious cutaneous nerve stimulation which allows to study small myelinated fibres. We investigated CSP in patients with demyelinating or axonal polyneuropathy (PNP) in order to evaluate the involvement of A-delta fibres. Furthermore we estimated the correlation of CSP parameters with presence of neuropathic pain in these group of patients. Materials and methods: Eighty demyelinating PNP patients, 178 axonal PNP patients and 265 healthy controls underwent clinical [neurological examination, Medical Research Council Score, DN4 Questionnaire] and electrophysiological [motor root conduction time (MRCT), compound muscle action potentials (CMAP), sensory nerve action potentials (SNAP) and CSP
Abstracts of Poster Presentations / Clinical Neurophysiology 125, Supplement 1 (2014) S1–S339
P622 Lumbar spinal stenosis: an underestimated diagnosis? L. Teunissen 1 , F. Verheul 2 , S. Tromp 1 , J. Kelder 3 , M. van der Meulen 2 1 Clinical Neurophysiology, 2 Neurology, 3 St Antonius Hospital, Cardiology, St Antonius Hospital, Nieuwegein, Netherlands
Figure 2
nerves SNAPs were absent. Sural sensory responses are low in amplitude. She walked home unaided after three weeks stay in the hospital. Follow up EMGs were done nine weeks and 17 months later. Motor NCS were consistently normal in all four tests. SNAPs remained unobtainable from all upper limbs sensory nerves and peroneal nerves even after 17 months later. Sural sensory potentials remained low in amplitude. Clinically she feels back to normal however reflexes remained hyporeflexic. Conclusion: Ganglionopathy is a rare condition. Idiopathic, acute onset and monophasic course is presented. NCS obtained during acute illness revealed a different length dependent nature of neuropathy. Clinical recovery is not matched by routine NCS findings.
P621 A case of acquired neuromyotonia. Slow potassium channel dysfunction and the effect of voluntary contraction 1
2
3
1
M. Ballegaard , P. Born , M. Moldovan , C. Krarup 1 Rigshospitalet, Clinical Neurophysiology NF3063, Copenhagen, Denmark; 2 Rigshospitalet, Pediatrics, Copenhagen, Denmark; 3 University of Copenhagen, Neuroscience and Pharmacology, Copenhagen, Denmark Question: Prior nerve membrane excitability studies using QTRACK in acquired neuromyotonia were reported as normal. A 15y-old girl had a 6 month history of progressive generalized muscle cramps initiated by movements and preceded by flu-like illness. She had no family history. Methods: Electromyography was used to show myotonia. Nerve conduction studies were performed at rest and after a short and a long exercise test. QTRACK (Trond protocol) examined excitability properties of motor and sensory nerve membrane. Results: Electromyography (EMG) revealed 2-60 seconds 200Hz myotonic discharges. Recruitment pattern was normal. Motor unit potentials were normal without diplets, triplets or multiplets. Motor and sensory nerve conduction studies were normal and showed no decrement of the compound motor action potentials on 3 Hz repetitive stimuli. A short exercise test induced a 56% decrement. Subsequent 3Hz repetitive stimuli increased the decrement to 90%. A long exercise test was without decrement. A median nerve motor excitability study revealed an abnormal membrane accommodation (phase s2) after polarization and a reduced late subexcitability after a supramaximal stimulus. Sensory nerve excitability study was normal. Excitability studies in both parents and a sister and a brother were normal. She had no significant autoantibodies directed towards the voltage gated potassium channel. A test for intron point mutations in KCQN2 and KCQN3 was normal. We did not perform gene sequencing. A genetic test for congenital myotonia was normal. Conclusion: In this rare case of neuromyotonia both standard nerve conduction studies and QTRACK were abnormal. The excitability study supported the suspicion of an abnormal accommodation in this patient, and pointed to an abnormal function of the slow potassium channel responsible for the s2 phase. We suggest the abnormality in slowly inactivating potassium current as causative in a subgroup of patients with neuromyotonia.
Introduction: With overlapping symptoms and signs it can be difficult to differentiate lumbar spinal stenosis (LSS) from polyneuropathy (PNP). LSS is potentially treatable while PNP is often not. We assessed the prevalence of LSS in patients with symptoms of the legs and evaluated the value of history, neurological examination and electrophysiological investigation in recognising patients with LSS. Methods: Patients with sensory symptoms and/or weakness of both legs were included from June 2011 to March 2012. Patients with a history of typical neurogenic claudication or with symptoms of the hands were excluded. Every patient was seen by a neurologist and underwent nerve conduction studies, needle electromyography and an MRI of the lumbar spine. Patients were divided between a group with absolute LSS and a group without absolute LSS. Results: 59 patients were included, of whom 20 (34%) had an absolute LSS. Older age was a predictor for LSS (mean 75 versus 67 years, p=0.021). Patients with LSS significantly more often reported to experience cramps in the legs (6% versus 31%, p=0.049). Nerve conduction studies and needle electromyography could not differentiate patients with LSS from patients without LSS. Conclusions: LSS might be an underestimated diagnosis in patients with symptoms of the lower legs. Electrophysiological examination is not a potent tool to discriminate between PNP and LSS. It might warrant starting the work-up with an MRI of the lumbar spine to differentiate between PNP and LSS.
P623 Added value of the blink reflex in the evaluation of diabetic neuropathies E. Sisak County Hospital St. George, Neurology, Sfantul Gheorghe, Romania Question: Is there a correlation between the blink reflex (BR) and the electroneurography (ENG) in diabetic patients? Methods: The BR has been recorded in 35 diabetic patients, together with the ENG on motor and sensory peripheral nerves. The BR was obtained by stimulating separately the left and right supraorbital branch of the trigeminal nerve and recording each time the response in both orbicularis oculi muscles. The measures contained the latency of R1 and R2 responses, as well as the difference between sides. The ENG testing included the ulnar motor, median motor, radial sensitive, peroneal motor, tibial motor and sural nerves bilaterally. The following parameters were considered: distal latency, conduction velocity and amplitude of the CMAP and SNAP. Results: In the majority of patients (97%) both R1 and R2 latencies were prolonged with respect to normal values from the literature. These values did not correlate with the diabetes type, but showed a linear relationship with the time from the onset of the disease. The latency differences between sides were not statistically significant. ENG measures displayed the most prominent modifications in the sensory nerves of the inferior limbs, more axonal than demyelinating, then in the sensory nerves of the upper limbs, and finally the least affected being the motor nerves. The sural nerve was often unexcitable and in such instances it proved even more valuable to find an altered BR. The best correlation between BR and ENG was obtained when the R1 and R2 latency on the one hand, and the amplitude of the SNAP on the other hand were considered. Conclusions: Although a multitude of tests (mainly BR and ENG) allow a more reliable diagnosis, our study suggests that the BR can solely be a reliable determinant of a diabetic neuropathy in cases where the sural nerve cannot be excited.
P624 Ultrasound evidence of concomitant traumatic nerve lesions far from the trauma site C. Erra, P. De Franco, D. Coraci, G. Granata, I. Paolasso, L. Padua Università del Sacro Cuore, Roma, Roma, Italy Question: High-resolution ultrasound (US) of peripheral nerves is a valuable
Abstracts of Poster Presentations / Clinical Neurophysiology 125, Supplement 1 (2014) S1–S339
tool in the assessment of traumatic nerve lesions. Sometimes in traumatic nerve lesions multiple site damages can be observed. To identify cases of traumatic double site radial nerve involvement assessed through US. Methods: We retrospectively evaluated 36 patients admitted to our neurophysiology lab from January 2010 to March 2013 for traumatic radial nerve lesions following humeral fractures. All those patients underwent clinical, electrodiagnostic and sonographic evaluation. Results: In 14 patients a double site involvement of radial and posterior interosseous nerve was observed through US. Conclusions: Multiple site nerve lesions following a trauma can be suspected based on clinical evaluation (presence of non homogeneous motor or sensory deficit) but are difficult to demonstrate through electrodiagnostic assessment. US can help to detect unexpected nerve impairment and can help identify multiple site traumatic nerve lesions showing that they are often more frequent than we can diagnose with neurophysiology alone.
P625 Multimodal assessment of small fiber neuropathy: laser evoked potentials or skin biopsy? C. Créac’h 1,2 , J.-P. Camdessanche 3 , F. Robert 3 , J.-C. Antoine 3 , R. Peyron 1,2 , P. Convers 2,3 1 CHU Saint-Etienne, Pain Center, Saint-Etienne, France; 2 Inserm 1028-Central Integration of Pain Lab, Centre for Neurosciences, Lyon & Saint-Etienne, France; 3 CHU Saint-Etienne, Neurology, Saint-Etienne, France Question: Laser Evoked Potentials (LEPs) and Skin Biopsy (SB) are both considered as reliable methods for assessing a diagnosis of Small Fiber Neuropathy (SFN). The issue is whether these two methods are redundant or not. Methods: We selected 67 patients (42F, 25M; 54±14 years) with probable pure painful SFN including the feet. All of them had thermo-algesic hypesthesia (either observed clinically or confirmed by quantitative sensory testing). LEPs was considered as abnormal if N2P2 was abnormal on at least 2 areas out of the 8 explored (third cervical dermatoma, hands, thighs, feet). SB was considered as abnormal if the density of intra-epidermal nerve fibers (IENFD) was abnormal either on proximal (thighs) or distal (leg) areas. We compared the sensitivity of these techniques and explored clinical factors that may predict these results. Results: Only 58% of patients had abnormal IENFD while 79% of patients had abnormal LEPs. The concordancy between SB and LEPs was 55% on proximal areas and 51% on distal areas. There was 2.5 fold more patients with abnormal LEPs and normal SB than patients with normal LEPs and abnormal SB (23 vs 9 patients). These results were not explained by the length-dependent characteristics of SFN nor by the duration of pain evolution. Burning pain was the only clinical factor predicting abnormal SB (OR=4.1; p=0.024). Conclusions: The discrepancies between LEPs and SB may provide in part from differential lesions of A delta and C fibers. In practice we may recommend to record LEPs in a first approach in case of expected painful pure SFN.
P627 Is precautionary neurophysiological monitoring useful for beta-thalassemia patients? P. Nemtsas 1 , V. Perifanis 2 , E. Koutsouraki 1 , A. Orologas 1 , M. Arnaoutoglou 1 1 University General Hospital of Thessaloniki AHEPA, 1st Department of Neurology, Thessaloniki, Greece; 2 University General Hospital of Thessaloniki AHEPA, First Propedeutic Department of Internal Medicine, Thessaloniki, Greece The thalassemias are the most common single gene disorder in the world. Over the last years, a limited number of studies, mainly in children, have demonstrated a mild peripheral neuropathy in b-thalassemia patients. Chronic hypoxia, iron overload, desferrioxamine (DFO) neurotoxicity and bone marrow expansion are implicated, but sufficient explanatory evidence and biomarkers development is envisaged. We perform motor conduction studies of the median, ulnar, peroneal and tibial nerves, as well as sensory conduction studies of the median, ulnar, peroneal and sural nerves in adults. For the first time to our knowledge, we use extended EMG studies (brachioradialis, abductor digiti quinti (hand), extensors carpi radialis, anterior tibialis, quadriceps rectus femoris) to reveal and better analyze peripheral neuropathy in these patients. Our findings are correlated with the history, the laboratory findings and the medication followed. As life expectancy
S219
for b-thalassemia patients extends, we support the use of neurophysiologic monitoring in order to achieve the appropriate management and as a result a better life quality for this patient group.
P628 Electrophysiological data of DSMA1 patients in the Netherlands X. Stalpers 1 , A. Verrips 1 , B.-T. Poll-The 2 , J.M. Cobben 3 , I. Snoeck 4 , I. de Coo 5 , A. Brooks 6 , S. Bulk 7 , R. Gooskens 8 , A. Fock 9 , C. Verschuuren-Bemelmans 10 , R. Sinke 10 , M. de Visser 11 , H. Lemmink 10 1 Canisius Wilhelmina Hospital, Neurology, Nijmegen, Netherlands; 2 Emma Children’s Hospital, Academic Medical Center, Pediatric Neurology, Amsterdam, Netherlands; 3 Emma Children’s Hospital, Academic Medical Center, Pediatric Genetics, Amsterdam, Netherlands; 4 Juliana Children’s Hospital, Pediatrics, The Hague, Netherlands; 5 Erasmus Medical Center, Neurology, Rotterdam, Netherlands; 6 Erasmus Medical Center, Clinical Genetics, Rotterdam, Netherlands; 7 Wilhelmina Children’s Hospital, University Medical Center Utrecht, Medical Genetics, Utrecht, Netherlands; 8 Wilhelmina Children’s Hospital, University Medical Center Utrecht, Neurology, Utrecht, Netherlands; 9 University Medical Center Groningen, Neurology, Groningen, Netherlands; 10 University Medical Center Groningen, Genetics, Groningen, Netherlands; 11 Academic Medical Center, Neurology, Amsterdam, Netherlands Question: What are characteristic electrophysiological findings in DSMA1 patients? Background: Distal spinal muscular atrophy type 1 (DSMA1) is a rare disorder with distal muscle weakness, hypotonia and early respiratory difficulties as most striking symptoms. The pathophysiology is unknown. Some think the anterior horn cell is primarily affected, followed by degeneration of axons, others think it is vice versa. The former is supported by spinal cord autopsy data and findings in the animal model, the latter is supported by sural nerve biopsies and the early and severe changes in nerve conduction studies. Methods: We collected electrophysiological data of 10 Dutch DSMA1 patients. Results: Electrophysiological findings showed mostly reduced or absent compound muscle action potential (CMAP) and sensory nerve action potential (SNAP) amplitudes. Nerve conduction velocities are markedly reduced and could be in the demyelinating range. Distal motor latency (DML) was generally not in the demyelinating range, considering CMAP amplitudes below 1mV being less trustworthy. None of the patients showed evidence for conduction block. Electromyography could be normal or show spontaneous muscle fiber activity and reinnervation. Electrodiagnostic findings best fit an axonal neuropathy (Table 1, see p. S220). Conclusions: In these 10 Dutch DSMA1 patients, electrodiagnostic findings suggest a severe axonal neuropathy. Our findings make the anterior horn cell as the primary site of the disorder less likely. References: Diers A, Kaczinski M, Grohmann K, et al. The ultrastructure of peripheral nerve, motor-end plate and skeletal muscle in patients suffering from spinal muscular atrophy with respiratory distress type 1 (SMARD1). Acta Neuropathol 2005;110;289-97.
P629 A neurophysiological study of A-delta fibres in demyelinating and axonal polyneuropathies through cutaneous silent period recordings D. Lopergolo 1 , B. Isak 1,2 , M. Gabriele 1 , E. Onesti 1 , G. Tartaglia 1 , A. Biasiotta 1 , S. La Cesa 1 , G. Di Stefano 1 , A. Truini 1 , M. Inghilleri 1 1 “Sapienza” University of Rome, Department of Neurology and Psychiatry, Rome, Italy; 2 Marmara University, Istanbul, Turkey Introduction: Cutaneous silent period (CSP) is a brief pause in voluntary muscle contraction following noxious cutaneous nerve stimulation which allows to study small myelinated fibres. We investigated CSP in patients with demyelinating or axonal polyneuropathy (PNP) in order to evaluate the involvement of A-delta fibres. Furthermore we estimated the correlation of CSP parameters with presence of neuropathic pain in these group of patients. Materials and methods: Eighty demyelinating PNP patients, 178 axonal PNP patients and 265 healthy controls underwent clinical [neurological examination, Medical Research Council Score, DN4 Questionnaire] and electrophysiological [motor root conduction time (MRCT), compound muscle action potentials (CMAP), sensory nerve action potentials (SNAP) and CSP