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.

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.

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.

The reliability of medial and lateral plantar nerve recordings in healthy elderly individuals.

The aim of this study was to investigate the reliability of medial plantar (MP) and lateral plantar (LP) nerve conduction studies (NCS) in healthy individuals aged >65 years, and to obtain reference values for this age group. The study included 81 healthy subjects. MP response was absent in only 2 subjects, but LP response could not be obtained bilaterally in 43 of the 81 subjects. Regression analysis showed that MP NCS could be reliably performed in those aged ≤ 72 years and normal values for MP nerve in individuals aged 66-72 years would be strongly against a large-fiber neuropathy. However, LP response was absent in 53.1 % of the healthy elderly subjects; therefore, we think it is unreliable to study the LP nerve in this age group.

Palmar cutaneous nerve conduction in patients with carpal tunnel syndrome.

OBJECTIVE: This study aimed to assess palmar cutaneous branch of the median nerve (PCBm) conduction in patients with clinically diagnosed carpal tunnel syndrome (CTS), to compare PCBm conduction with that of the median and ulnar nerves, and to determine the PCBm conduction abnormality rate in patients with CTS. MATERIALS AND METHODS: The study included 99 hands of 60 patients with clinical CTS and 38 hands of 38 healthy controls. Sensory nerve conduction study (NCS) was performed on the median nerve, ulnar nerve, and PCBm, and onset latency, conduction velocity and amplitude were recorded. Additionally, differences in latency and velocity between the median nerve and PCBm, and the difference in latency between the median and ulnar nerves were calculated. RESULTS: In all, 56% of the patients with CTS had abnormal PCBm conduction. Additionally, in 7 of 8 hands with abnormal sensation--both in the thenar eminence and abnormal sensory distribution along the main branch--NCS of the PCBm was also abnormal. CONCLUSIONS: The PCBm is not ideal as a comparator nerve for the neurophysiological diagnosis of CTS. The frequency of PCBm abnormality in CTS patients may be related to the concomitant damage in both of these nerves. Additionally, the present findings may help explain, at least in part, why patients with CTS often exhibit sensory involvement beyond the classical median nerve sensory borders.

Motor nerve impairment in diabetic patients with symmetrical distal sensory polyneuropathy: a single nerve fiber conduction velocity study.

INTRODUCTION: In this study we investigated the clinical utility of single fiber conduction velocity (SF-CV) testing in the evaluation of motor nerve function in diabetic patients with signs and symptoms of symmetrical distal sensory polyneuropathy (DSP). SF-CV findings were compared with conventional nerve conduction studies (NCS). METHODS: Twenty-eight consecutive type 2 diabetic patients with clinically diagnosed DSP were studied. RESULTS: SF-CV testing of the tibial nerve was abnormal in 16 (57.1%) patients. Twelve patients with normal conventional motor NCS had abnormal findings by tibial SF-CV. SF-CV testing of the tibial nerve was significantly superior to all other motor NCS. CONCLUSIONS: SF-CV testing of the tibial nerve often demonstrates motor nerve impairment in diabetic patients with sensory DSP when conventional NCS are normal.

Physical and mental fatigue in myasthenia gravis and its correlation with other symptoms.

INTRODUCTION: Muscle weakness and easy fatigability are the clinical hallmarks of myasthenia gravis (MG). However, fatigue perception, which can be seen quite often in myasthenic patients, and its effect on the quality of life, irrespective of motor deficit, has not been elucidated yet. The aim is to evaluate the frequency of fatigue in myasthenic patients with nearly full muscle strength and the effect of fatigue on quality of life by assessing its correlation with other symptoms. METHODS: Fifty-three patients with ocular or mild generalized MG in remission or minimal manifestations completed the questionnaires measuring the severity of MG and quality of life (MG Composite Scale and MG-Activities of Daily Living Profile). Both patient group and control group (53 healthy volunteers)completed the scales assessing fatigue [Fatigue Assessment Scale (FAS) and Fatigue Impact Scale (FIS)], depression [Beck Depression Inventory (BDI)] and sleep (Epworth Sleepiness Scale). Disease severity was assessed using MG Foundation of America (MGFA) and MGFA Post-Intervention Status classifications. RESULTS: FAS, FIS physical and BDI scores were significantly higher in patients compared to the control group (p = 0.003, p = 0.001, and p = 0.003, respectively) and fatigue was associated with depression and daytime sleepiness. Inpatient group, depressive symptoms and daytime sleepiness were higher in females (p = 0.019 and p = 0.013). The mean values of FIS total and cognitive scores were higher in patients with generalized MG (p = 0.033 and p = 0.045). Fatigue scores correlated with motor signs. DISCUSSION: Fatigue can be seen in MG independently from muscle weakness and is an important symptom worsening the quality of life.

Assessment of symptomatic diabetic patients with normal nerve conduction studies: utility of cutaneous silent periods and autonomic tests.

Established electrophysiological methods have limited clinical utility in the diagnosis of small-fiber neuropathy (SFN). In this study, diabetic patients with clinically diagnosed SFN were evaluated with autonomic tests and cutaneous silent periods (CSPs). Thirty-one diabetic patients with clinically suspected SFN and normal nerve conduction studies were compared with 30 controls. In the upper extremities (UE), the CSP parameters did not differ statistically between the patient and control groups, whereas, in the lower extremities (LE), patients had prolonged CSP latencies (P = 0.018) and shortened CSP durations (P < 0.001). The sensitivity of the CSP duration was 32.6%, and the specificity was 96.7%. The expiration-to-inspiration ratios and amplitudes of the sympathetic skin responses in the lower extremities were also reduced. Our findings indicate that the diagnostic utility of CSPs was higher than that of the autonomic tests to support the clinically suspected diagnosis of SFN.

Where is the core of the volcano? The undetermined origin of primary restless legs syndrome.

An association between small fiber neuropathy and primary Restless Legs Syndrome (RLS) is suggested since both of them share common characteristics. Our aim was to investigate the existence of autonomic neuropathy on the basis of autonomic tests. The patients and the age-matched controls were evaluated with Neuropathy Symptom Profile and Autonomic Symptom Profile, nerve conduction studies (NCS), and autonomic tests. Patients suffered from neuropathic and autonomic complaints obviously. There was no significant difference for NCS, heart rate variability tests, and sympathetic skin responses (SSRs) among patients and controls. Since both the NCSs and the autonomic tests were within normal, the complaints were considered to be the consequences of the problem in sensory integration due to the dysfunction of the caudal diencephalic A11 group, rather than a neuropathic process. The cardiac autonomic imbalance possibly emerges as a consequence of arousal periods prior to or during the Periodic Leg Movements (PLM) episodes during sleep, but not due to autonomic neuropathy.

Clinical utility of F wave parameters in unilateral S1 radiculopathy.

OBJECTIVE: To investigate the F wave parameters (F duration, F minimum latency, F maximum latency, F mean latency, F chronodispersion, and F persistence) of the tibial nerve with unilateral S1 radiculopathy. We evaluated the differences of these parameters between the affected and unaffected sides and also with the control group. METHODS: The study was performed from September 2007 to January 2008 in the Electrophysiology Laboratory of Marmara University Medical Faculty, Istanbul, Turkey. Bilateral tibial F waves were obtained from 20 normal control subjects (control group) and 20 patients with unilateral S1 radiculopathy (patient group). Minimum, maximum, and mean F latency values were corrected by the subject`s height (F min/H, F max/H, F mean/H). Needle electromyography was performed in the patient group. The patients with a history of diabetes, alcoholism, or other abnormality known to affect peripheral nerves were excluded. RESULTS: In the control group, no significant differences were found in any of the F-wave parameters between the 2 sides. In the patient group, there were significant prolongations of F duration, F min/H, F max/H, F mean/H, and F chronodispersion on the lesion side. Patients` F durations of the affected and unaffected side were significantly longer than the control group. The F chronodispersion also showed significant prolongation on the affected side in the patient group compared with the control group. Among 20 patients, 15 had evidence of denervation or polyphasic potentials on needle electromyography. CONCLUSION: The F wave study can be clinically useful in the evaluation of S1 radiculopathies, especially in patients with mild and early stage of the disease. Both F duration and F chronodispersion have a higher diagnostic value as compared to F min in the diagnosis of lumbosacral radiculopathy, especially in cases with normal findings on needle electromyography.

Madras motor neuron disease in Turkey.

We present a 19-year-old female patient complaining of hoarseness and eyelid drooping. The neurological examination and laboratory investigations including genetic, radiological and electrophysiological evaluations were consistent with a juvenile-onset, predominantly bulbar, motor neuron disease with sensorineural hearing loss. The syndrome fulfilled the diagnostic criteria of Madras Motor Neuron Disease (MMND). Very few cases with MMND have been reported to date, and the majority are from south-eastern Asia. This is the first case reported from Turkey and indicates that the disease is not only regional but may also occur on the basis of rare de novo mutations.

Medial plantar and dorsal sural nerve conduction studies increase the sensitivity in the detection of neuropathy in diabetic patients.

OBJECTIVE: Clinical utility of nerve conduction studies (NCS) of the medial plantar and dorsal sural nerves in the early detection of polyneuropathy have already been shown separately. However, at present, there is no data about the combined assessment of these two nerves in distal sensory neuropathy. In the present study, we aimed to evaluate the medial plantar and dorsal sural NCS in a group of diabetic patients with distal sensory neuropathy (DSN) and in healthy controls. METHODS: Thirty healthy and 30 diabetic adult patients were included. In all subjects, peripheral motor and sensory NCS were performed bilaterally with surface electrodes on the lower limbs including medial plantar and dorsal sural nerves. In addition, motor and sensory nerves were studied unilaterally on the upper limb. RESULTS: In all patients, nerve action potential (NAP) amplitudes of sural and superficial peroneal nerves were within normal ranges, but in the patient group mean value was significantly lower than in the controls. Among clinically defined 30 DSN patients, medial plantar NAP amplitude was abnormal in 18 (60%) and dorsal sural nerve amplitude was abnormal in 13 (40%) of the patients bilaterally. Additionally, the onset NCV of the dorsal sural nerve was significantly slower in patients than controls (P=0.038). Evaluation of both of these nerves increased the sensitivity up to 70% in the detection of neuropathy. CONCLUSIONS: Bilateral NCS assessment of both of the medial plantar and dorsal sural nerves together increases the rate of diagnosis of diabetic distal sensory neuropathy compared to assessment of either of these nerves. SIGNIFICANCE: Assessment of medial plantar in addition to dorsal sural NCS together increases the sensitivity in the detection of neuropathy and allows earlier diagnosis, especially when routine NCS are normal.

Brainstem Reflexes in Systemic Lupus Erythematosus Patients Without Clinical Neurological Manifestations.

INTRODUCTION: We aimed to assess central and peripheral nervous system involvement in systemic lupus erythematosus (SLE) patients without any neurological signs and symptoms by performing electrophysiological investigations. METHODS: Thirty-eight SLE patients and 35 healthy volunteers participated in this study. Peripheral nerve conduction and brainstem reflexes were evaluated by performing nerve conduction studies (NCSs) and blink reflex (BR) and masseter inhibitory reflex (MIR) recordings. RESULTS: Eleven patients (29%) had an abnormality in at least 1 NCS parameter, and 1 (2.6%) patient was diagnosed with polyneuropathy. The number of patients with abnormal BR and MIR was 23 (60.5%) and 14 (37%), respectively. The contralateral R2 latency of BR and the silent period 1 (SP1) latency of MIR were significantly prolonged in the patients compared with the controls (p=0.015 and p<0.001, respectively). CONCLUSION: This study showed that irrespective of peripheral nervous system involvement, brainstem reflexes could be affected in SLE patients even without clinical neurological findings. Brainstem reflex abnormalities suggested that the functional integrity of the inhibitory or excitatory interneurons in the lateral caudal pons and lateral medulla is disturbed in SLE patients.

Topiramate and accommodation: Does topiramate cause accommodative dysfunction?

OBJECTIVE: To investigate the accommodation function in topiramate users. DESIGN: Case-control clinical study. PARTICIPANTS: The participants included 16 controls and 22 patients using 100 mg/kg topiramate who were diagnosed with migraine according to the International Classification of Headache Disorders, second edition criteria. METHODS: One-minute dynamic measurements of refraction with accommodation stimuli of 0 D, 2 D, 2.5 D, 3 D, 4 D, and 5 D were obtained using the open field refractometer WAM-5500 in. RESULTS: In most of the accommodation stimuli ranges (0 D, 2.5 D, 3 D, and 5 D), topiramate users had a significantly higher accommodative lag compared with controls (p = 0.028, p = 0.014, p = 0.011, and p = 0.011, respectively). The most important causes of accommodative lag were found to be accommodation stimulus and inclusion in the topiramate group (p < 0.001, R2 = 0.32, 95% CI 0.22-0.37 and 0.42-0.91, respectively). Multivariate linear regression analysis revealed that the 2 most important predictors of accommodative lag were accommodation stimulus and age (p < 0.001, r = 0.51, 95% CI 0.31-0.32 and 0.67-0.69, respectively) CONCLUSIONS: Even after adjustment for age, accommodative lag is greater across several accommodative stimulus levels in patients using topiramate, which may be related to visual symptoms in topiramate users.

Motor-Unit Number Estimation Is Sensitive in Detecting Motor Nerve Involvement in Patients with Carpal Tunnel Syndrome.

BACKGROUND AND PURPOSE: We compared the motor-unit number estimation (MUNE) findings in patients who presented with signs and/or findings associated with carpal tunnel syndrome (CTS) and healthy controls, with the aim of determining if motor-unit loss occurs during the clinically silent period and if there is a correlation between clinical and MUNE findings in CTS patients. METHODS: The study investigated 60 hands of 35 patients with clinical CTS and 60 hands of 34 healthy controls. Routine median and ulnar nerve conduction studies and MUNE analysis according to the multipoint stimulation method were performed. RESULTS: The most common electrophysiological abnormality was reduced conduction velocity in the median sensory nerve (100% of the hands). The MUNE value was significantly lower for the patient group than for the control group (p=0.0001). ROC analysis showed that a MUNE value of 121 was the optimal cutoff for differentiating between patients and controls, with a sensitivity of 63.3% and a specificity of 68.3%. MUNE values were lower in patients with complaints of numbness, pain, and weakness in the median nerve territory (p<0.05, for all comparisons), and lower in patients with hypoesthesia than in patients with normal neurological findings (p=0.023). CONCLUSIONS: The MUNE technique is sensitive in detecting motor nerve involvement in CTS patients who present with sensorial findings, and it may be useful in detecting the loss of motor units during the early stages of CTS. Larger-scale prospective clinical trials assessing the effect of early intervention on the outcome of these patients would help in confirming the possible benefit of detecting subclinical motor-unit loss in CTS.

Blink reflex in migraine headache.

OBJECTIVE: Activation of trigeminovascular system is thought to play an important role in migraine pathogenesis. Blink reflex (BR) test is an easy method to study the trigeminal system. Latencies recorded in BR test were evaluated to examine neurophysiological changes that occur in migraine patients. METHODS: A total of 40 patients diagnosed with migraine (9 with aura and 31 without aura) according to the International Headache Society (IHS) International Classification of Headache Disorders, 2nd edition, and 30 healthy control subjects were assessed using BR test. Supraorbital nerve was stimulated on each side, and unilateral early component (R1), and bilateral late component (R2) latencies were evaluated. RESULTS: Significantly longer latency values were recorded on both right and left sides (RR1 and LR1) as well as both ipsilateral and contralateral R2 on the left side (LR2i and LR2c) in the migraine group compared to the control group. Longer RR1 and LR1 latencies were found in patients with migraine who had an attack at the time of study (p<0.01). There was no statistically significant correlation between the location of pain and latencies in the interictal period (p>0.05). But significantly longer R1 and R2i latencies were found at the symptomatic side of patients examined during the headache attack (p=0.037 and p=0.028 respectively). There was no statistically significant correlation between the recorded latencies and gender, attack duration, attack frequency and migraine type (p>0.05). CONCLUSION: Results of BR test in the present study are thought to point to a dysfunction in brainstem and trigeminovascular connections of patients with migraine headache and support the trigeminovascular theory of migraine.

A neurophysiological approach to the complex organisation of the spine: F-wave duration and the cutaneous silent period in restless legs syndrome.

OBJECTIVE: It is generally accepted that F-wave duration (FWD) and the cutaneous silent period (CSP) are influenced by diminished central inhibition. The aim of this study was to diagnose patients of restless legs syndrome (RLS) with the help of FWD and/or CSP parameters. METHODS: In all, 24 patients with primary RLS were compared with 31 age- and sex-matched controls. The participants were evaluated based on nerve conduction study (NCS), F-wave parameters (minimum, maximum and mean latency; chronodispersion, persistence and duration; and the ratio of the mean FWD to compound muscle action potential (CMAP) duration), CSP (latency, duration and the ratio of lower-extremity (LE) to upper-extremity (UE) duration that is, silent period ratio (SPR)), the expiration to inspiration ratio (E/I) and sympathetic skin response (SSR). RESULTS: There were not any significant differences in NCS, E/I or SSR between the patients and controls. However, FWD was prolonged (P<0.0001 for UE and LE) and FWD/CMAP duration was increased in upper and lower extremities (P<0.001 for UE and P<0.0001 for LE). Further, CSP latencies in UE (P=0.030) and LE (P<0.001) were prolonged, and CSP duration and SPR were significantly reduced in the patient group (P<0.0001). CONCLUSIONS: As both NCS and autonomic test results were in the normal range, abnormalities in FWD and CSP parameters were attributed to the dysfunction of different interneuron groups in the spine. SIGNIFICANCE: The use of FWD and CSP could aid in the diagnosis of RLS patients in whom conventional electrophysiological procedures are ineffective.