An exploratory study of delayed flash visual evoked potential P2 wave latency in subcortical arteriosclerotic encephalopathy.

BACKGROUND: Patients with cognitive dysfunction may present with significantly prolonged the P2 wave latency of flash visual evoked potential. However, no studies have been reported on whether the P2 wave latency of flash visual evoked potential is prolonged in patients with subcortical arteriosclerotic encephalopathy (SAE). OBJECTIVE: To examine the relationship between flash visual evoked potential P2 wave latency (FVEP-P2 wave latency) and cognitive impairment in patients with SAE. METHODS: Overall, we recruited 38 SAE patients as the observation cohort (OC) and 34 healthy volunteers as the control cohort (CC). We measured the FVEP-P2 wave latency for both groups. The SAE patients' cognitive abilities were evaluated via mini-mental state examination (MMSE) and the association between the latency of FVEP-P2 and MMSE score was explored by Pearsons´s correlation test. RESULTS: There is no significant difference between OC (21 males and 17 females; 68.6 ± 6.7 years of age and 9.6 ± 2.8 years of education) and CC (19 males and 15 females; 65.3 ± 5.9 years of age and 10.1 ± 2.6 years of education) in gender and age composition and education level. The FVEP-P2 wave latency of the CC group was (108.80 ± 16.70) ms and the OC FVEP-P2 wave latency was (152.31 ± 20.70) ms. The OC FVEP-P2 wave latency was significantly longer than the CC (P < 0.05). In terms of MMSE scores, the MMSE scores of CC was (28.41 ± 2.34), and that of OC was (9.08 ± 4.39). Compared to the CC, the OC MMSE score was significantly lower (P < 0.05). In addition, the FVEP-P2 wave latency was inversely related to the MMSE (r = -0.4465, P < 0.05) in SAE patients. CONCLUSION: The FVEP-P2 wave latency wave latency was significantly prolonged in SAE patients and strongly associated with the degree of cognitive dysfunction.

Single-fiber F waves compared with conventional surface F waves, and their utility in detecting early diabetic neuropathy.

INTRODUCTION: The single-fiber F-wave (SFF-wave) technique assesses the entire length of single motor fibers using a concentric needle. Herein we investigated the utility of this approach in the detection of early diabetes-related neuropathy, and compared it with the use of conventional surface F waves (CF waves). METHODS: Sixteen patients with diabetes and either no neuropathy or mild neuropathy were assessed and compared with 16 age- and height-matched control participants. RESULTS: Both CF and SFF waves were abnormal in all 5 patients who had mild neuropathy. However, SFF waves demonstrated subclinical abnormalities in 7 of 11 patients (64%) with no neuropathy, whereas only 2 of these patients (18%) had prolonged CF waves. Minimum F-wave latency was comparable between techniques, but maximum SFF-wave latency was more frequently prolonged, as these delayed motor units were better isolated, rather than buried among summated CF-wave responses. DISCUSSION: SFF waves highlight the segmental involvement in diabetic neuropathy, and use of the SFF-wave technique detects more abnormalities than with CF waves. Muscle Nerve 58: 665-670, 2018.

Auditory brainstem response (ABR) waveform analysis program.

Auditory brainstem responses (ABR) are a high-throughput assessment of auditory function. Many studies determine changes to the threshold at frequencies that span the normal hearing range of their test subjects, but fewer studies evaluate changes in waveform morphology. The goal of developing this program was to make a user-friendly semiautomatic peak-detection algorithm to encourage widespread analysis of the amplitudes and latencies of the ABR, which may yield informative details about the integrity of the auditory system with development, aging, genetic manipulations, or damaging conditions. This method incorporates automated peak detection with manual override and inter-rater validation to calculate the amplitude and latency for waves 1-5, as well as interpeak latencies and amplitude ratios between waves. The output includes raw data and calculations in a format compatible with graphical and statistical software.•The method yields a high-throughput peak-detection algorithm with manual override and inter-rater capabilities to streamline ABR waveform analysis.•Data output includes amplitudes, latencies, amplitude ratios, and interpeak latencies for generation of input-output curves.•While complete automation of peak detection with this tool is dependent on good signal-to-noise ratios, relevant amplitude and latency calculations are fully automated, and manual spot-checking is simplified to significantly reduce the time to analyze waveforms.

Bone Conduction Cervical Vestibular Evoked Myogenic Potentials as an Alternative in Children with Middle Ear Effusion.

OBJECTIVE: To compare the amplitude ratio and P-wave latency of cervical vestibular evoked myogenic potentials (c-VEMPs) for bone conduction (BC) and air conduction (AC) stimulation in children with otitis media with effusion (OME). MATERIAL AND METHODS: This is an observational study of a cohort of 27 children and 46 ears with OME. The c-VEMP amplitude ratio and P-wave latency were compared between BC and AC in children with OME and healthy age-matched children. RESULTS: The c-VEMP response rate in children with OME was 100% when using BC stimulation and 11% when using AC stimulation. The amplitude ratio for BC was significantly higher in the OME group than the age-matched healthy control group (p = 0.004). When focusing on ears with an AC c-VEMP response (n = 5), there was a significant difference in the amplitude ratio between the AC and BC stimulation modes, but there was no significant difference in the AC results between the OME group and the age-matched control group. CONCLUSIONS: BC stimulation allows for reliable vestibular otolith testing in children with middle ear effusion. Given the high prevalence of OME in children, clinicians should be aware that recording c-VEMPs with AC stimulation may lead to misinterpretation of otolith dysfunction in pediatric settings.

F-wave parameters and body mass index in carpal tunnel syndrome.

BACKGROUND: Severe carpal tunnel syndrome (CTS) readily lends itself to both clinical and electrophysiological recognition. The uncertainty sometimes is in identifying and quantifying motor involvement in mild and, perhaps, in moderate CTS. Our study aimed to evaluate F responses in mild and moderate CTS and determine the contribution of BMI to the F-wave parameters. METHODS: A retrospective review of the clinical and electrophysiological data of patients with CTS seen at the clinical neurophysiology laboratory of Aga Khan Hospital, Dar es Salaam, between 1 August 2017 and 31 July 2019 was retrieved. Carpal tunnel syndrome was graded according to the electrophysiological criteria of Padua. The F-wave parameters of patients with mild-to-moderate CTS were analyzed and compared with asymptomatic controls. RESULT: We studied 91 hands. Twenty-two hands were asymptomatic controls, 30 hands had mild CTS, and 39 hands had moderate CTS. Patients with moderate CTS were more obese (p =.011), had more females (p =.044), and were older (p= <0.001). F-wave parameters were not convincingly different between mild and moderate CTS. F-wave chronodispersion (p =.035) and F-wave persistence (0.019) were significantly different between nonobese control and mild and moderate CTS. Median-ulnar F-wave latency difference (FWLD) was significant between obese patients with mild CTS and moderate CTS scores (p =.017). CONCLUSION: Although a clear difference exists between F-wave parameters in asymptomatic controls and those with CTS, the F-wave study is inadequate in distinguishing mild and moderate CTS even in the context of BMI. Median-ulnar F-wave latency difference (FWLD) appeared to be a promising discriminant parameter between obese patients with mild CTS and those with moderate CTS.

Effect of Umbilical Cord Ferritin Level on Auditory Brainstem Response Threshold in Newborns.

INTRODUCTION: Iron plays an important role in myelination. Ferritin is a reliable indicator of the tissue iron store and umbilical cord ferritin level reflects the in utero iron stores. Objective is to study the effect of the umbilical cord ferritin level on the ABR recording in the newborn. MATERIALS AND METHODS: The study was conducted in a tertiary care hospital in India with a sample of 250. The study group was divided into Group A (with umbilical cord ferritin level of ≤ 75ng/ml) and Group B (umbilical cord ferritin level > 75ng/ml). Correlation analysis was carried out to study the relation between ferritin level and latency of wave I,III and V. Two sample t test was done between the two groups to study the significance of latency and amplitude of various ABR waves. RESULTS: There was no correlation between the ferritin and ABR threshold as well as latency and amplitude of ABR waves. A significant prolongation of the absolute latency of wave V and the interwave latency of III - V and I -V of both the ears was found in Group A. The amplitude of the ABR waves did not show any statistical difference between the two groups. CONCLUSION: Ferritin levels effect the latency of wave V of ABR and this may be attributed to slow conduction time secondary to altered myelination. Measurement of serum ferritin may be considered as a routine protocol in newborn babies after delivery or before discharge from hospital.

Ontogeny of auditory brainstem responses in the bat, Phyllostomus discolor.

Hearing is the primary sensory modality in bats, but its development is poorly studied. For newborns, hearing appears essential in maintaining contact with their mothers and to develop echolocation abilities. Here we measured auditory brainstem responses (ABRs) to clicks and narrowband tone pips covering a large frequency range (5-90 kHz) in juveniles (p7 to p200) and adults of the bat, Phyllostomus discolor. Tone-pip audiograms show that juveniles at p7 are already quite responsive, not only below 20 kHz but up to 90 kHz. Hearing sensitivity increases further until about p14 and is then refined, possibly correlated with growth and differentiation of the animals' outer ears. ABR amplitudes decrease within the first 3-4 months, inversely correlated with the bat weight and forearm length. ABR Wave I latency decreases with increasing stimulation level. ABR duration (measured between Waves I and V) is longer in juveniles and shortens with age which may reflect temporal refinement of auditory brainstem neurons to accommodate the exceptional temporal precision required for effective echolocation. Overall our data show that P. discolor bats have good hearing very early in life. The current method represents a fast and minimally invasive way of characterizing basic hearing in bats.

Terminal Latency Index, Residual Latency, and Median-Ulnar F-Wave Latency Difference in Carpal Tunnel Syndrome.

INTRODUCTION: Carpal tunnel syndrome (CTS) is the most common entrapment neuropathy, but no electrodiagnostic test alone shows sufficient sensitivity for CTS. We aimed to investigate the value of median motor terminal latency index (mTLI), median motor residual latency (mRL), and median-ulnar F-wave latency difference (FdifMU) as additional tests to nerve conduction studies which are performed traditionally in electromyography laboratories. METHODS: This is a retrospective study. The results of electrodiagnostic studies performed on patients with CTS were examined. We divided the enrolled hands of the patients diagnosed with CTS into two groups: affected hands with abnormal electroneuromyographic parameters indicating CTS diagnosis (CTS group) and hands with normal electroneuromyographic parameters (control group). Then, we analyzed the results of these completed electrodiagnostic studies. RESULTS: A total of 320 hands of 160 patients were studied. FdifMU and mRL were found to be significantly higher in CTS group compared with the control group (P < 0.001). mTLIs were found to be significantly higher in control group compared with the CTS group (P < 0.001). Given that, the area under the curve is more than 70% for mTLI and mRL, but not for FdifMU. CONCLUSION: When combined with mMDL, both mTLI and mRL have excellent specificity for the diagnosis of mild and moderate CTS. However, the sensitivities for both parameters were lower. In suspected patients, FdifMU can be an additional tool for the diagnosis of CTS also, but alone it is not valuable.

Impact of hematopoietic stem cell transplant on VEP and ABR values of the patients with malignant infantile osteopetrosis.

OBJECTIVES: Malignant Infantile Osteopetrosis (MIOP) is a rare inherited disorder with neurological complications, notably visual impairment and decrease of hearing level. Although Hematopoietic Stem Cell Transplantation (HSCT) has been approved as the only curative treatment for these patients, the exact impact of it on visual and hearing level is still unclear. STUDY DESIGN: We analyzed the P2 latency and amplitude from Visual Evoked Potentials (VEP) of 10 patients (20 eyes) and the threshold of wave V from Auditory Brainstem Response (ABR) of 15 patients (30 ears) with MIOP before, 6 and 12 months after HSCT. RESULTS: Before the HSCT, 10/30 ears demonstrated some degree of hearing loss; while only 3/20 eyes had P2 wave latencies in normal range for age. Using GEE models, it was shown that 12 months after HSCT, wave V threshold of ABR of the patients was significantly lower compared to its value from before the transplant (p value: 0.04). The analysis of latency and amplitude of P2 wave of VEPs showed no significant difference between before and after the transplant. CONCLUSION: This study clearly showed that HSCT can improve the hearing level of the patients in terms of ABR threshold. Although HSCT made no significant improvement in latency of P2 in VEP of the patients, it can be concluded that transplant can halt visual regression in these patients. Early diagnosis of MIOP with this objective tools and subsequently early HSCT in these patients can decrease the rate of neurological complications of MIOP and improve the quality of life in them.

Brainstem auditory evoked potential abnormalities in type 2 diabetes mellitus.

BACKGROUND: Diabetes mellitus represents a syndrome complex in which multiple organ systems, including the central nervous system, are affected. AIM: The study was conducted to determine the changes in the brainstem auditory evoked potentials in type 2 diabetes mellitus. MATERIALS AND METHODS: A cross sectional study was conducted on 126 diabetic males, aged 35-50 years, and 106 age-matched, healthy male volunteers. Brainstem auditory evoked potentials were recorded and the results were analyzed statistically using student's unpaired t-test. The data consisted of wave latencies I, II, III, IV, V and interpeak latencies I-III, III-V and I-V, separately for both ears. RESULTS: The latency of wave IV was significantly delayed only in the right ear, while the latency of waves III, V and interpeak latencies III-V, I-V showed a significant delay bilaterally in diabetic males. However, no significant difference was found between diabetic and control subjects as regards to the latency of wave IV unilaterally in the left ear and the latencies of waves I, II and interpeak latency I-III bilaterally. CONCLUSION: Diabetes patients have an early involvement of central auditory pathway, which can be detected with fair accuracy with auditory evoked potential studies.

Auditory evoked potential in handled and non-handled iron-deficient rats

Iron deficiency alters metabolism, neurotransmission, glial integrity and the cortical myelin layer, besides increasing myelinization time. Environmental stimulation (handling) improves morphological, biochemical, electrophysiological and behavioral aspects of both well-nourished and malnourished animals. The objective of the present study was to determine the effects of an irondeficient diet and of handling on the brainstem auditory evoked potential (BAEP) of rats during development. Ninety-six male rats were divided since birth into Well-nourished (W, 35 mg iron/kg) and Anemic (A, 4 mg iron/kg) groups, and subdivided into Handling (H) and No Handling (NH). Body weight, hemoglobin (Hb), hematocrit (Ht), latencies of waves I, II, III IV, I-IV interpeak interval, and response threshold to auditory stimuli were evaluated at 18, 22, and 32 days. W animals presented higher Hb and Ht levels than A animals at 18, 22 and 32 days. The animals presented longer latencies of waves I, II, III and IV and I-IV interpeak interval of BAEP at 18 than at 22 and 32 days, and AH18 rats presented longer latencies of waves I and II than AH22 and AH32 rats, and longer wave I latency than WH18 animals. Iron deficiency increased the latencies of BAEP waves, suggesting damage to the myelin layer, especially during the early development, and the effects of handling were more evident along time in anemic animals.