Electrodiagnostic methods to verify Guillain-Barré syndrome subtypes in Istanbul: A prospective multicenter study.

BACKGROUND AND AIMS: This study aimed to identify the clinical characteristics and electrodiagnostic subtypes of Guillain-Barré syndrome (GBS) in Istanbul. METHODS: Patients with GBS were prospectively recruited between April 2019 and March 2022 and two electrodiagnostic examinations were performed on each patient. The criteria of Ho et al., Hadden et al., Rajabally et al., and Uncini et al. were compared for the differentiation of demyelinating and axonal subtypes, and their relations with anti-ganglioside antibodies were analyzed. RESULTS: One hundred seventy-seven patients were included, 69 before the coronavirus disease 2019 pandemic (April 2019-February 2020) and 108 during the pandemic (March 2020-March 2022), without substantial changes in monthly frequencies. As compared with the criteria of Uncini et al., demyelinating GBS subtype diagnosis was more frequent according to the Ho et al. and Hadden et al. criteria (95/162, 58.6% vs. 110/174, 63.2% and 121/174, 69.5%, respectively), and less frequent according to Rajabally et al.'s criteria (76/174, 43.7%). Fourteen patients' diagnoses made using Rajabally et al.'s criteria were shifted to the other subtype with the second electrodiagnostic examination. Of the 106 analyzed patients, 22 had immunoglobulin G anti-ganglioside antibodies (14 with the axonal subtype). They had less frequent sensory symptoms (54.5% vs. 83.1%, p = 0.009), a more frequent history of previous gastroenteritis (54.5% vs. 22.9%, p = 0.007), and a more severe disease as compared with those without antibodies. INTERPRETATION: Serial electrodiagnostic examinations are more helpful for accurate subtype diagnosis of GBS because of the dynamic pathophysiology of the disease. We observed no significant increase in GBS frequency during the pandemic in this metropolis.

Corneal nerve fiber involvement in chronic inflammatory demyelinating polyneuropathy.

BACKGROUND: Despite the primary myelin-related pathophysiology, small fiber neuropathy (SFN) and axonal degeneration are also considered to be involved and associated with disabling symptoms and impaired quality of life in chronic inflammatory demyelinating polyneuropathy (CIDP). Demonstration of SFN usually requires complex or invasive investigations. OBJECTS: In vivo corneal confocal microscopy (IVCCM) has evolved as a non-invasive, easily applied method for quantification of small fiber involvement in peripheral nerve disorders. We aimed to investigate the potential role of IVCCM in CIDP. METHODS: In this cross-sectional study, 15 patients with CIDP underwent assessment with clinical disability scales, neuropathic pain (NP) and autonomic symptom questionnaires, nerve conduction studies, and IVCCM. IVCCM parameters were analyzed and compared to those from 32 healthy controls. RESULTS: Corneal nerve fiber density (CNFD) and corneal nerve fiber length (CNFL) were significantly decreased in the CIDP group, compared to those in controls (p = 0.03 and p = 0.024, respectively). Langerhans cells and fiber tortuosity were increased in CIDP patients (p = 0.005 and p = 0.001, respectively). IVCCM parameters were significantly lower in patients with NP compared to those in patients without NP. CONCLUSION: IVCCM shows promise as a non-invasive complementary biomarker in the assessment of demyelinating polyneuropathies, providing insights into the potential pathophysiology of these non-length-dependent neuropathies.

Reference jitter values for the sternocleidomastoid muscle with concentric needle electrodes.

BACKGROUND: The aim of this study was to establish reference jitter values for the voluntary activated sternocleidomastoid (SCM) muscle using a concentric needle electrode (CNE). METHODS: The study included 39 healthy participants (20 female and 19 male) aged 18-77 y. Jitter was expressed as the mean consecutive difference (MCD) of 80-100 consecutive discharges. Filters were set at 1 and 10 kHz. The mean MCDs for all participants were pooled, and the mean value +2.5 SD was accepted as the upper limit for the mean MCD. The upper limit for individual MCD was calculated using +2.5 SD of the upper 10th percentile MCD for individual participants. RESULTS: Mean age of the participants was 45 ± 14.5 y. Mean MCD was 16.20 ± 2.23 µs (range: 12-21 µs), and the upper limit of normal for mean MCD was 21.8 µs. The mean value for 823 individual jitters was 23.3 ± 4.61 µs (range: 6.6-36.9 µs), and the upper limit of normal for each individual jitter was 34.6 µs. CONCLUSIONS: The present findings indicate that upper normal limit for mean MCD is 22 µs and for individual data it is 35 µs.

Revisiting the complex architecture of ALS in Turkey: Expanding genotypes, shared phenotypes, molecular networks, and a public variant database.

The last decade has proven that amyotrophic lateral sclerosis (ALS) is clinically and genetically heterogeneous, and that the genetic component in sporadic cases might be stronger than expected. This study investigates 1,200 patients to revisit ALS in the ethnically heterogeneous yet inbred Turkish population. Familial ALS (fALS) accounts for 20% of our cases. The rates of consanguinity are 30% in fALS and 23% in sporadic ALS (sALS). Major ALS genes explained the disease cause in only 35% of fALS, as compared with ~70% in Europe and North America. Whole exome sequencing resulted in a discovery rate of 42% (53/127). Whole genome analyses in 623 sALS cases and 142 population controls, sequenced within Project MinE, revealed well-established fALS gene variants, solidifying the concept of incomplete penetrance in ALS. Genome-wide association studies (GWAS) with whole genome sequencing data did not indicate a new risk locus. Coupling GWAS with a coexpression network of disease-associated candidates, points to a significant enrichment for cell cycle- and division-related genes. Within this network, literature text-mining highlights DECR1, ATL1, HDAC2, GEMIN4, and HNRNPA3 as important genes. Finally, information on ALS-related gene variants in the Turkish cohort sequenced within Project MinE was compiled in the GeNDAL variant browser (www.gendal.org).

Cutaneous silent period in myofascial pain syndrome.

INTRODUCTION: An increased response to painful stimuli without spontaneous pain suggests a role of central hyperexcitability of pain pathways in the pathogenesis of myofascial pain syndrome (MPS). In this study we aimed to test the hypothesis that spinal pain pathways are affected in MPS. We used cutaneous silent period (CSP) parameters to demonstrate the hyperexcitability of spinal pain pathways in MPS. METHODS: Twenty-nine patients diagnosed with MPS and 30 healthy volunteers were included in the study. The CSP recordings were performed in the right upper and left lower extremities. RESULTS: In both upper and lower extremities, patients had prolonged CSP latencies (P = 0.034 and P = 0.049 respectively) and shortened CSP durations (P = 0.009 and P = 0.008, respectively). DISCUSSION: Delayed and shortened CSP in MPS patients implies dysfunction in the inhibitory mechanism of the spinal/supraspinal pain pathways, suggesting central sensitization in the pathogenesis of MPS and supporting our research hypothesis. Muscle Nerve 57: E24-E28, 2018.

Ulnar nerve entrapment at elbow in obstructive sleep apnea patients: a randomized controlled trial.

PURPOSE: Obstructive sleep apnea (OSA) is a highly prevalent disease. For diagnostic and therapeutic purposes, OSA has been divided into several subgroups. Positional OSA (POSA), the most frequent subgroup (56 %), is described as overall apnea hypopnea index (AHI) ≥5 and supine AHI at least twice as high when compared to non-supine AHI. We aimed to investigate the frequency of ulnar nerve entrapment neuropathy at the elbow (UNEE) in OSA patients without clinical signs and symptoms of ulnar neuropathy and intended to find if sleeping position in OSA had an impact on UNEE development. METHODS: Fifty POSA, 48 non-positional OSA (NPOSA) patients, and 45 healthy controls without diabetes mellitus, hypothyroidism, rheumatic diseases, and cervical radiculopathy underwent nerve conduction studies. RESULTS: We found that UNEE was highly frequent in OSA patients (42.9 %) and significantly more frequent in moderate to severe POSA patients than mild POSA patients (65.4 vs. 33.3 %, p < 0.05). Furthermore, when compared to non-positional ones, UNEE was significantly more frequent in moderate to severe POSA patients (65.4 vs. 36.4 %, p < 0.05). CONCLUSIONS: Our results showed that the severity of OSA in positional patients was correlated with increased frequency of UNEE. OSA patients should be informed about the predisposition of UNEE and questioned for the symptoms in periodical controls. POSA patients should be alerted about the additional effect of sleeping position on UNEE and the necessity of OSA treatment should be emphasized.

Somatosensory evoked potentials as a screening tool for diagnosis of spinal pathologies in children with treatment refractory overactive bladder.

PURPOSE: To evaluate the usefulness of somatosensory evoked potential as a screening tool for spinal pathologies in patients with treatment refractory overactive bladder. METHODS: This prospective study was performed between January 2011 and January 2014. Children >5 years old with treatment refractory overactive bladder were enrolled after exclusion of anatomical and neurological causes of incontinence. All patients underwent urodynamic studies, spinal MRI, and somatosensory evoked potential (SEP). Sensitivity, specificity, PPV, and NPV were calculated for SEP. RESULTS: Thirty-one children (average age 8.3 ± 2.9 years) were included in the study. SEP was abnormal in 13 (41.9%), and MRI was abnormal in 8 (25.8%) patients. SEP was found to have a sensitivity of 87.5%, a specificity of 73.9%, positive predictive value of 53.85%, and negative predictive value (NPV) of 94.4%. CONCLUSION: In patients with treatment refractory OAB, SEP is an important tool for the screening of tethered cord/spinal pathologies. Our results suggest that a child with a normal SEP study in this group of patients may not require further investigation with MRI.

Medial plantar-to-radial amplitude ratio: does it have electrodiagnostic utility in distal sensory polyneuropathy?

PURPOSE OF THE STUDY: We proposed a new electrophysiological parameter medial plantar (MP)-to-radial amplitude ratio (MPRAR), similar to sural-to-radial amplitude ratio (SRAR), in the diagnosis of distal sensory polyneuropathy (DSP), based on the concept that distal nerves are affected more and earlier than proximal nerves in axonal neuropathies. We aimed to investigate the diagnostic sensitivity of this parameter in diabetic DSP, together with sensitivities of SRAR and MP nerve action potential (NAP) amplitude. MATERIALS AND METHODS: In 124 healthy controls and 87 diabetic patients with clinically defined DSP and normal sural responses, we prospectively performed sensory nerve conduction studies (NCS), and evaluated the MP NAP amplitude, MPRAR and SRAR values. We determined the lower limits of normal (LLN) of these parameters in the healthy controls and calculated their sensitivities and specificities in detecting DSP in diabetic patients. RESULTS: MP nerve amplitude and MPRAR values were significantly lower in the patient group, compared to controls. However, SRAR values did not differ significantly between the two groups. The LLN of MP NAP amplitude was found to be 4.1 µV. The cutoff values for SRAR and MPRAR were determined as 0.24 and 0.16, respectively. MPRAR was abnormal in 21.8% of patients. However, the most sensitive parameter in detection of DSP was MP NAP amplitude, which showed a sensitivity of 31% and a specificity of 100%. CONCLUSIONS: Although MPRAR is more sensitive than SRAR in detecting DSP, it does not provide additional diagnostic yield to the assessment of MP NCS alone in diabetic DSP patients with normal sural responses.

Exome sequencing reveals homozygous TRIM2 mutation in a patient with early onset CMT and bilateral vocal cord paralysis.

Charcot-Marie-Tooth disease is a heterogeneous group of inherited distal symmetric polyneuropathies associated with mutations in genes encoding components essential for normal functioning of the Schwann cell and axon. TRIM2, encoding a ligase that ubiquitinates the neurofilament light chain, was recently associated with early-onset neuropathy in a single patient. We report a TRIM2 homozygous missense mutation (c.2000A>C; p.D667A) in a patient with peripheral neuropathy and bilateral vocal cord paralysis, allowing for further delineation of the associated phenotypic spectrum.