G C Claussen

University of Alabama at Birmingham, Birmingham, Alabama, United States

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Publications (48)124.52 Total impact

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    ABSTRACT: Objective To identify molecular signatures in muscle from patients with amyotrophic lateral sclerosis (ALS) that could provide insight into the disease process and serve as biomarkers.MethodsRNA sequencing was performed on ALS and control muscle samples to identify Smad family members as potential markers of disease. Validation studies were performed in a cohort of 27 ALS patients and 33 controls. The markers were assessed in the G93A superoxide dismutase (SOD)1 mouse at different stages of disease and in a model of sciatic nerve injury.ResultsSmad8, and to a lesser extent Smad1 and 5, mRNAs were significantly elevated in human ALS muscle samples. The markers displayed a remarkably similar pattern in the G93A SOD1 mouse model of ALS with increases detected at preclinical stages. Expression at the RNA and protein levels as well as protein activation (phosphorylation) significantly increased with disease progression in the mouse. The markers were also elevated to a lesser degree in gastrocnemius muscle following sciatic nerve injury, but then reverted to baseline during the muscle reinnervation phase.InterpretationThese data indicate that Smad1, 5, 8 mRNA and protein levels, as well as Smad phosphorylation, are elevated in ALS muscle and could potentially serve as markers of disease progression or regression.
    Annals of Clinical and Translational Neurology. 09/2014;
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    ABSTRACT: INTRODUCTION: METHODS: We compared the problems or complications associated with electrodiagnostic testing in 77 patients with implanted cardiac devices. Thirty tests were performed after magnet placement, and 47 were performed without magnet application. RESULTS: All electrodiagnostic tests were performed safely in all patients without any serious effect on the implanted cardiac devices with or without magnet placement. A significantly higher number of patient symptoms and procedure changes were reported in the magnet group (P < 0.013). No statistical difference was found in the testing difficulty or ECG changes. CONCLUSION: The magnet group patients had an approximately 11-fold greater risk of symptoms than those in the control group. Our data do not support a recommendation that magnet placement is necessary for routine electrodiagnostic testing in patients with implanted cardiac devices, as long as our general and specific guidelines are followed. Muscle Nerve, 2012.
    Muscle & Nerve 06/2012; · 2.31 Impact Factor
  • G.C. Claussen, M. Ohira, M. Alsharabati, S.J. Oh
    Clinical Neurophysiology. 06/2012; 123(6):e38.
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    ABSTRACT: In this investigation we report on the clinical utility of sensory nerve conduction studies of the medial femoral cutaneous (MFC) nerve. Sensory nerve conduction of the MFC nerve was assessed in 22 patients for whom this test was considered clinically necessary. MFC nerve conduction was abnormal in 4 cases of MFC neuropathy. The most common cause was iatrogenic in 14 femoral neuropathy cases. MFC nerve conduction showed absent or low-amplitude sensory nerve action potential (SNAP) in 13 cases, with femoral motor nerve conduction abnormal in 5 cases. In 2 cases with acute lumbar plexopathy, the MFC SNAP was absent unilaterally. MFC nerve conduction was normal in 1 case with diabetic lumbar radiculopathy and in another case with postpolio syndrome. Assessment of MFC nerve conduction is extremely useful in the diagnosis of femoral neuropathy, medial femoral cutaneous neuropathy, and lumbar plexopathy.
    Muscle & Nerve 02/2012; 45(2):195-9. · 2.31 Impact Factor
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    ABSTRACT: The diagnostic usefulness of the accessory nerve repetitive nerve stimulation (RNS) test was evaluated in 100 patients with myasthenia gravis (MG). The test was easy to perform and reliable at the low rates of stimulation. A higher diagnostic sensitivity was found in the accessory nerve RNS test than in the ulnar nerve RNS test on either the abductor digiti quinti or flexor carpi ulnaris muscles, especially in mild generalized MG. Diagnostic sensitivity was significantly increased when RNS test results for three muscles were combined, especially in mild generalized MG and sero-positive MG. In a small number of cases only the ulnar or accessory nerve RNS test was abnormal. There was a good correlation between electrophysiological and clinical severity of MG in the accessory nerve RNS test Thus, we conclude that the accessory nerve RNS test is a valuable second-line test and its greatest usefulness is in cases of mild generalized MG.
    European Journal of Neurology 01/2011; 2(5):492 - 497. · 4.16 Impact Factor
  • S. Oh, G. Claussen, M. B. Morgan, L. Lu, A. Young
    Clinical Neurophysiology - CLIN NEUROPHYSIOL. 01/2009; 120(2).
  • Clinical Neurophysiology - CLIN NEUROPHYSIOL. 01/2008; 119(3).
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    ABSTRACT: The nerve conduction findings in interdigital neuropathy of the foot (IDN; Morton's neuroma) have rarely been reported. We analyzed the nerve conduction data in 23 patients with suspected IDN studied between 1982 and 2002. Diagnosis of IDN was made on the basis of clinical features. All patients underwent routine nerve conduction studies and a near-nerve needle sensory nerve conduction study of the interdigital nerves by Oh's method in the symptomatic foot. Of the 23 patients, the diagnosis of definite IDN was made in 13 cases and of possible NDN in the others cases. Nineteen were females. Twenty two patients had only one nerve affected. One patient had two nerves affected. The III-IV interdigital nerve was affected in 17 cases and the II-III interdigital nerve in 7 cases. The near-nerve needle nerve conduction showed abnormality in the affected interdigital nerves in all definite IDN cases and confirmed the diagnosis of IDN in 10 cases by the abnormal dip phenomenon (a selective decrease of 50% or more in the sensory CNAP amplitude of the affected nerve compared with that of the preceding interdigital nerve). In 11 possible IDN cases, IDN was identified by the abnormal dip phenomenon. The near-nerve needle sensory nerve conduction of the interdigital nerves is a highly sensitive diagnostic test, and abnormal dip phenomenon is the most characteristic electrophysiological marker for the diagnosis of IDN.
    Arquivos de Neuro-Psiquiatria 10/2007; 65(3B):771-8. · 0.83 Impact Factor
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    ABSTRACT: In order to determine whether there is any difference between voltage-gated calcium-channel antibody (VGCC-Ab)-positive and -negative groups in Lambert-Eaton myasthenic syndrome (LEMS), we compared the clinical and electrophysiological features between 13 patients with VGCC-Ab and 6 VGCC-Ab-negative patients. No obvious difference was observed in the various clinical features or findings on single-fiber electromyography between seropositive and seronegative cases. In seropositive cases, the compound muscle action potential (CMAP) amplitude was lower but the increment on post-exercise facilitation (PEF) and high-rate stimulation (HRS) was significantly higher than in the seronegative group, indicating that the repetitive nerve stimulation (RNS) test in the seropositive group is more typical of LEMS and more severe. A 100% increment as the diagnostic criterion in the routine RNS test was satisfied in all seropositive cases but in only three seronegative cases, whereas a 60% increment as the diagnostic criterion was found in all seronegative cases. The classic triad (low CMAP amplitude, decrement at low rate of stimulation, and increment at PEF or HRS) of RNS is rare, adding to the difficulty in diagnosing LEMS in the seronegative group, and making a 60% increment criterion more critical for the diagnosis of this disorder.
    Muscle & Nerve 03/2007; 35(2):178-83. · 2.31 Impact Factor
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    ABSTRACT: To better define electrophysiological abnormalities in myasthenia gravis (MG) patients with muscle-specific tyrosine kinase (MuSK) antibodies (Ab), we compared electrophysiological features of 14 MuSK Ab-positive, 73 acetylcholine receptor antibody (AChR Ab)-positive, and 22 MuSK and AChR Ab-negative (seronegative) patients with generalized disease. Repetitive nerve stimulation (RNS) abnormalities were observed in 86% of MuSK Ab-positive and 82% of AChR Ab-positive patients but in only 55% of seronegative patients. RNS decrements in the orbicularis oculi were more common and severe in the MuSK Ab-positive patients than the other two groups. Single-fiber electromyography (SFEMG) of the extensor digitorum communis was abnormal in 90% of MuSK Ab-positive patients. The high frequency of RNS abnormalities in facial muscles in the MuSK Ab-positive population reflects the propensity for facial muscle involvement in this form of MG and emphasizes the importance of including facial muscles in RNS protocols when evaluating these patients.
    Muscle & Nerve 05/2006; 33(4):500-4. · 2.31 Impact Factor
  • Y. Hatanaka, G. C. Claussen
    Clinical Neurophysiology - CLIN NEUROPHYSIOL. 01/2006; 117:124-124.
  • Neurology 12/2005; 65(9):1508-9. · 8.25 Impact Factor
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    ABSTRACT: Various parameters of the repetitive nerve stimulation (RNS) test of the abductor digiti quinti muscle were analyzed statistically in 34 patients with Lambert-Eaton myasthenic syndrome (LEMS). The sensitivity and specificity of the increments after exercise and after 50-HZ stimulation for the diagnosis of LEMS were compared with reference values in 40 normal subjects and data from 538 tests in patients with myasthenia gravis (MG). When we used a 100% increment (the "gold standard") as the normal limit for the postexercise facilitation (PEF) or the high-rate stimulation (HRS) test, the diagnosis of LEMS was confirmed in 29 (85%) cases. When a 60% increment was used as the normal limit, the diagnosis of LEMS was made in 97% of cases. In MG, a 60% increment was observed in only 4 of 538 cases by HRS and in none by the exercise test. Thus, the use of a 60% increment showed a sensitivity of 97% for the diagnosis of LEMS and a specificity of 99% in excluding MG. A 60% increment in either the PEF or HRS test for the diagnosis of LEMS is a desirable alternative to the 100% increment previously considered to be the gold standard for this diagnosis.
    Muscle & Nerve 11/2005; 32(4):515-20. · 2.31 Impact Factor
  • J-H Seo, H F Ryan, G C Claussen, T D Thomas, S J Oh
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    ABSTRACT: Vasculitis is not usually considered as a cause of symmetric sensory neuropathy. To present the clinical, pathologic, and electrophysiologic features of 17 (16%) cases of sensory neuropathy in vasculitis (SNV) among 106 cases with histologically proven vasculitic neuropathy that were collected over the last 30 years. In 41% of cases, SNV was found as systemic vasculitic neuropathy in association with primary vasculitic disease. The most common clinical presentation was symmetric polyneuropathy, seen in 53% of cases. The most common nerve conduction pattern was diffuse neuropathy pattern of axonal degeneration. Sural nerve biopsy was diagnostic in 88% of cases. In two cases, muscle biopsy was necessary for the definite diagnosis of vasculitis. Non-systemic SNV is usually benign. Of 11 patients followed for longer than 2 years, none developed motor weakness due to neuropathy. Sensory neuropathy, regardless of symmetry, can be due to vasculitis.
    Neurology 10/2004; 63(5):874-8. · 8.25 Impact Factor
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    ABSTRACT: To report the clinical, electrophysiologic, and histologic characteristics of subacute inflammatory demyelinating polyneuropathy (SIDP) and to present the diagnostic criteria of this disease. For a diagnosis of "definite SIDP," there were four mandatory criteria: 1) progressive motor and/or sensory dysfunction consistent with neuropathy in more than one limb with time to nadir between 4 and 8 weeks, 2) electrophysiologic evidence of demyelination in at least two nerves, 3) no other etiology of neuropathy, and 4) no relapse on adequate follow-up. Supportive criteria included high spinal fluid protein level (>55 mg/dL) and inflammatory cells in the nerve biopsy. A diagnosis of "probable SIDP" required progression of demyelinating neuropathy over a 4- to 8-week period. Sixteen definite SIDP patients were identified among 29 probable SIDP patients. An antecedent infection was found in 38% of cases. The two most common neuropathy types were a symmetric motor-sensory neuropathy and a pure motor neuropathy. Cranial nerve deficits and respiratory failure were rare. Spinal fluid protein was high in 93% of cases. Demyelination was documented by the motor nerve conduction in 88% of cases and by the near-nerve needle sensory nerve conduction in two cases. Almost all patients were treated with prednisone and some with additional immunotherapies. Complete recovery was achieved in 69% of cases and partial recovery in others. Definite SIDP had all the characteristics of CIDP with three exceptions: a higher rate of antecedent infection, no relapse rate, and a high rate of recovery to normal. Subacute inflammatory demyelinating polyneuropathy is a definite entity bridging the gap between Guillain-Barré syndrome and chronic inflammatory demyelinating polyneuropathy.
    Neurology 01/2004; 61(11):1507-12. · 8.25 Impact Factor
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    ABSTRACT: A young woman presented with facial myokymia in association with dermatomyositis. There was no evidence of peripheral neuropathy. Needle electromyography showed prominent myokymic discharges and brief neuromyotonic discharges in addition to many small-amplitude, short-duration motor unit potentials. Myokymia and dermatomyositis both responded to immunosuppressive treatment. The presence of antibodies to voltage-gated potassium channels and the association with dermatomyositis indicated an autoimmune cause for myokymia, which may have been due to reversible peripheral nerve hyperexcitability. Muscle Nerve 27: 757–760, 2003
    Muscle & Nerve 05/2003; 27(6):757 - 760. · 2.31 Impact Factor
  • Anna Tseng, Gwen C Claussen, Shin J Oh
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    ABSTRACT: There have been a few reports in the literature documenting the effects of calcium-channel blockers in Lambert-Eaton myasthenic syndrome (LEMS). We report a case of a patient with LEMS who developed respiratory failure after administration of diltiazem and verapamil. A patient with LEMS, associated with small-cell carcinoma in remission, developed multifocal atrial tachycardia, necessitating the use of diltiazem and verapamil, which led to respiratory failure and intubation 5 days after admission. The patient was taken off all calcium-channel blockers and weaned off the respirator after 6 days. Oral time-release diltiazem was restarted without further exacerbation of LEMS. Most likely the combined use of two different calcium-channel blockers, verapamil and diltiazem, was responsible for this patient's respiratory failure. To date, 5 cases (2 patients with LEMS and 3 with myasthenia gravis) in which cardiac calcium-channel blockers had a definite detrimental effect have been reported.
    Journal of clinical neuromuscular disease 01/2003; 4(2):60-3.
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    ABSTRACT: Postexercise facilitation (PEF) with clinical reflexes, H-reflex, and T-reflexes at the ankle and knee was systematically studied in 16 patients with Lambert-Eaton myasthenic syndrome (LEMS). PEF was observed in ankle and knee deep tendon reflexes in five patients, in H-reflex in three patients, and in T-reflexes in six patients. When all reflex tests were combined, 7 (43.7%) of 16 patients showed PEF by at least one test. The authors conclude that the PEF of reflexes, the most helpful diagnostic clinical marker for LEMS, is not common.
    Neurology 11/2002; 59(7):1085-7. · 8.25 Impact Factor
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    ABSTRACT: Near-nerve needle sensory nerve conduction of plantar nerves in 100 patients with distal sensory neuropathy with normal routine nerve conduction (DSN-NNC) found the definite neuropathy pattern (abnormality in more than three of six tested nerves) in 65%, axonal neuropathy in 35%, and the known cause in 37% of patients. Absent or diminished reflexes were a reliable indicator for large fiber neuropathy (LFN). This near-nerve needle plantar nerve study provides useful and unequivocal evidence of its value in identifying neuropathy in DSN-NNC by finding LFN in 65% of patients.
    Neurology 07/2001; 56(11):1570-2. · 8.25 Impact Factor
  • S J Oh, M Demirci, B Dajani, A C Melo, G C Claussen
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    ABSTRACT: The superficial peroneal nerve subserves sensation on the entire surface of the dorsum of the foot, except in small areas. All previously reported techniques for evaluating nerve conduction along this nerve tested a proximal portion of the nerve. We report a new method for evaluating sensory nerve conduction of the four branches of the distal superficial peroneal nerve. Two branches to the second and third toes of the medial dorsal cutaneous nerve and two branches to the fourth and fifth toes of the intermediate dorsal cutaneous nerve were studied orthodromically and antidromically in 37 feet of 21 normal volunteers using surface stimulating and recording electrodes and with a distance of 10 cm between the stimulating and recording electrodes. Maximum nerve conduction velocities (NCV) ranged from 41.8 to 46.9 m/s, and mean response amplitude ranged from 6.5 to 7.6 microV with the orthodromic technique. Values for NCV were almost identical when elicited by antidromic and orthodromic techniques, but response amplitudes were higher with the antidromic technique. Mean amplitudes of the distal superficial peroneal nerve were about 50% of the proximal superficial peroneal, and the conduction velocity in the distal superficial peroneal was slower than that in the proximal superficial peroneal nerve, by 8-14 m/s. In seven cases, distal superficial peroneal neuropathy was confirmed with this technique: two with proper digital neuropathy, two with medial dorsal cutaneous neuropathy, and three with intermediate dorsal cutaneous neuropathy.
    Muscle & Nerve 06/2001; 24(5):689-94. · 2.31 Impact Factor

Publication Stats

464 Citations
124.52 Total Impact Points

Institutions

  • 1993–2014
    • University of Alabama at Birmingham
      • Department of Neurology
      Birmingham, Alabama, United States
  • 2004
    • Chonbuk National University
      • School of Medicine
      Seoul, Seoul, South Korea