Evoked potentials. With special reference to the diagnostic value in multiple sclerosis

Macular ganglion cell-inner plexiform layer defect patterns in multiple sclerosis patients without optic neuritis: A Spectral-Domain-Optical Coherence Tomography Cross-Sectional, Case-Control, Pilot Study

PURPOSE

Spectral-domain optical coherence tomography (SD-OCT) was used to evaluate, in patients with multiple sclerosis without a history of optic neuritis (MSNON), the proportion of the different macular ganglion cell-inner plexiform layer complex (mGCIP) defect patterns. The results were compared with those of healthy controls (HCs).

METHODS

In this cross-sectional case-control study, 34 eyes of 34 individuals, 17 with MSNON and 17 HCs, were evaluated. All participants underwent mGCIP thickness measurement using SD-OCT (Zeiss Cirrus HD-OCT 4000, macular cube protocol). The mGCIP defect patterns were classified in nine types (minimal, inner, outer, diffuse mild, diffuse severe inferior confined, inferior dominant, superior confined, and superior dominant), according to the shape derived by the deviation map of the instrument, and the proportion of each type was assessed.

RESULTS

A mGCIP defect pattern was detected in 70.5% of MSNON eyes, with an inner type as the most frequent pattern (47%), followed by the outer type (11.7%) and the inferior confined type (11.7%). No defect was found in Hcs.

CONCLUSIONS

A significant thinning of the mGCIP with the frequent presence of an inner defect was seen in MSNON patients. The presence of this defect may serve as a biomarker of subclinical optic nerve involvement in MS patients.

Pattern Visually Evoked Potentials in Japanese Girl With Optic Neuritis and Seropositive to Anti-myelin Oligodendrocyte Glycoprotein (MOG) Antibody

Purpose: To describe a Japanese girl with unilateral optic neuritis who was seropositive for the anti-myelin-oligodendrocyte glycoprotein (MOG). Serial recordings of the pattern visual evoked potentials (pVEPs) were made to follow the dynamic changes of the disease activity.

Observations: A 5-year-old girl developed a sudden reduction of vision and deep ocular pain in her right eye. On examination at our university hospital, the best-corrected visual acuity (BCVA) was light perception, and a swelling of the optic disc and tortuous vessels at the posterior pole of the right eye were observed. MRI demonstrated that her right optic nerve was hyperintense on short TI inversion recovery (STIR) sequence. A diagnosis of right papillitis was made, and she was treated with steroid pulse therapy followed by a gradual tapering of oral prednisolone. The visual acuity decreased to no light perception and plasmapheresis combined with high-dose intravenous immunoglobulin therapy was performed. The decimal visual acuity rapidly improved and recovered to 1.2, and no recurrence was observed for at least 1 year. On day 19, she was found to be anti-MOG antibody positive and anti-Aquaporin 4 antibody negative. pVEPs were recorded during the course of the disease process which showed the dynamic changes of the physiology of the visual pathways. The implicit times of the N75 and P100 components were prolonged in the right eye in the acute phase. The right visual acuity remained at 1.2 for at least 1 year, but the implicit times of the N75 and P100 components of the pVEPs of the right eye were still prolonged compared to left eye.

Conclusion: Our findings indicate a positive relationship between the anti-MOG antibodies-positivity and the prolonged pVEPs. Further analyses of the pVEPs and other clinical findings of the optic neuritis are needed to establish the clinical significance of the anti-MOG antibodies positivity and optic neuritis for the diagnosis, treatment, and prognosis for this disease.

Changes in oxygen saturation and the retinal nerve fibre layer in patients with optic neuritis - a pilot study

PURPOSE

Assessment of retinal oxygen saturation, thickness of a retinal nerve fibre layer (RNFL) and functional changes in the optic nerve during optic neuritis (ON) in patients with multiple sclerosis (MS).

METHODS

Thirty-two patients with ON due to MS within 3 months of onset of symptoms were enrolled [22 females, 10 males, age 34 ± 9 years, median 32.5 years, 22 patients with the clinically isolated syndrome (CIS), 10 patients with relapsing-remitting from of MS (RRMS)]. All patients were examined using optical coherence tomography (OCT model 4000, Carl Zeiss Meditec, Dublin, CA, USA), automatic optical oximetry (Oxymap ehf, Reykjavik, Iceland) and using visual evoked potentials (VEP) (Metronic Keypoint^® , Minneapolis, MN, USA).

RESULTS

Arterio-venous difference (AVD) was increased in patients ON affected eye compared to patients' unaffected eye (PUE) [34.2 ± 4.7 versus 31.3 ± 4.6, p = 0.044 (mean ± standard deviation)]. No statistically significant difference was found in vessel oxygen saturation as well as in RNFL thickness in ON affected eyes when compared to unaffected MS eyes and healthy individuals. Significantly lower optic nerve conduction velocity was found in the affected eye when compared to unaffected MS eye and healthy (p < 0.0001 for both comparisons). No correlation between oxygen saturation values and VEP was observed in patients with MS.

CONCLUSION

The AVD in oxygen saturation is altered in patients with acute ON. In the early stage of ON, AVD could reflect inflammatory and metabolic changes in the affected eye. Therefore, oximetry could be used as another diagnostic method in MS patients in suspicion of ON. This result would be promising for future investigation in this field.

Conventional Perimetry, Short-Wavelength Automated Perimetry, Frequency-Doubling Technology, and Visual Evoked Potentials in the Assessment of Patients with Multiple Sclerosis

PURPOSE

To evaluate the diagnostic power of conventional, achromatic, automated perimetry (CAP), short-wavelength automated perimetry (SWAP), frequency-doubling technology (FDT) perimetry, and visual evoked potentials (VEP) in a group of patients with multiple sclerosis (MS) with or without a history of optic neuritis.

METHODS

Thirty eyes of 15 patients (5 male, 10 female, average age 38+/-7 years) with confirmed diagnosis of MS underwent CAP, SWAP (Humphrey 750-II VFA, program central 30-2, full-threshold strategy), FDT perimetry (program N-30), and pattern VEPs. Sixteen eyes (53.3%) had no history of ocular involvement and a negative ophthalmologic examination. They were matched with a control group of 10 healthy volunteers (4 male, 6 female, average age 31+/-10 years). The mean deviation (MD) and the pattern standard deviation (PSD) of the two groups were compared (t-test). Fourteen eyes (46.7%) had, on the contrary, a history of optic neuritis. Inside this group, the MD and the PSD of the three techniques were correlated (Spearman's rank test), in order to investigate whether any significant differences might be revealed by these techniques in pointing out the total amount of visual field damage.

RESULTS

When comparing MS patients without signs or symptoms of ocular involvement and a control group, no significant differences were found for CAP MD, CAP PSD, and FDT PSD. Significant differences were found, on the contrary, for SWAP MD (p=0.0014), SWAP PSD (p=0.0001), and FDT MD (p=0.0001). When considering the MD and the PSD of the three techniques in the group of MS patients who had a history of optic neuritis, a significant correlation was found only between CAP MD and SWAP MD (r=0.0057), with a tendency by SWAP to reveal a higher rate of visual field loss. The other correlations were not significant. According to predefined criteria, the group of asymptomatic subjects had abnormal CAP in 1 eye (6.25%), abnormal SWAP in 9 (56.2%), abnormal FDT in 11 (68.7%), and abnormal VEPs in 7 (43.7%). The combined use of all techniques allowed us to identify silent optic nerve impairment in 15 (93.7%) eyes.

CONCLUSIONS

Short-wavelength automated perimetry and FDT perimetry are two non-conventional perimetric techniques that were mainly developed for the early detection of glaucomatous damage. The results of this study demonstrate their efficacy also in detecting early visual field deficits in MS patients without clinical signs of optic neuropathy. Frequency doubling perimetry, in particular, proved to be an easy, fast, and sensitive technique in the assessment of patients with MS. Our results also suggest that subclinical visual involvement in MS can be better diagnosed using multiple (neurophysiologic and psychophysical) tests.

Electrophysiological and clinical correlates of corpus callosum atrophy in patients with multiple sclerosis

Multiple sclerosis (MS) is an idiopathic inflammatory demyelinating disorder of the central nervous system (CNS) characterized by demyelination and axonal degeneration. Corpus callosum (CC) is commonly involved during the disease process leading to atrophy (93%). Currently, there are no established markers of disease progression and the interplay of processes leading to brain atrophy in MS remains unknown. The primary aim of this study was to assess the frequency of CC atrophy in MS patients. Furthermore, the relationship between expanded disability status scale (EDSS) and transcranial magnetic stimulation (TMS) evoked motor potentials (MEP) were assessed to capture disease effects by independent parameters. Seventy-nine MS patients and 50 controls were included and their CC volumes were assessed. Out of 79 patients, 31 patients (39·2%) had CC atrophy. The distribution of EDSS scores among the group with CC atrophy [13 (32%) patients with EDSS 0-2; 11 (58%) patients with EDSS 2-4; 19 (24%) patients with EDSS ≥4] was not statistically significant (p>0·05). MEP latency was abnormal in 34 (43%) patients, 67 (85%) patients had abnormal MEP amplitude and CMCT was abnormal in 32 (41%) patients. The relation between EDSS and MEP was statistically significant among the patient population including the subgroup of patients with CC atrophy (p<0.05). Our results lacked to provide an association between disability and CC atrophy, but there was a correlation between CC atrophy and TMS evoked motor potentials. Early evolution of axonal degeneration and brain atrophy should be considered in terms of follow-up measures to provide long-term efficiency impacting disability, progression and brain atrophy.

Predictive role of evoked potential examinations in patients with clinically isolated optic neuritis in light of the revised McDonald criteria

To analyse the sensitivity and role of somatosensory and motor evoked potentials (EP) in patients with a first episode of clinically isolated optic neuritis (ON) in predicting the development and course of multiple sclerosis (MS), 27 patients with ON underwent EP and magnetic resonance imaging (MRI) examinations at presentation. Follow-up MRI scans were also performed (mean: 20, range: 4-48 months). It was found that 2/27 patients did not fulfill the MRI (McDonald) and clinical criteria of MS upon follow-up and also had normal EP results. Abnormal EP results were found in 6/27 patients and all of them had follow-up MRI results fulfilling the revised McDonald criteria of MS; 4/6 patients in this group were also diagnosed as clinically definitive MS. The majority, 19/27 patients had normal EP results, but went on to develop MS based on follow-up MRI results and McDonald criteria. Of these patients, however, only 3/19 converted to clinically definitive MS as well. The baseline MRI was abnormal in similar proportions (4/6 and 12/19) in these last two groups of patients. Thus, abnormal EP examinations at the first episode of ON can be considered as a predictive factor only for the earlier clinical conversion to MS - in this respect, however, being more sensitive than the initial MRI - and as such they may contribute to the delineation of the patient group who may benefit from early immunomodulatory treatment. They do not however have a predictive value for the development of MS itself as diagnosed by the McDonald criteria.

Escalating morphine exposures followed by withdrawal in feline immunodeficiency virus-infected cats: a model for HIV infection in chronic opiate abusers

Opiate abuse is a risk factor for human immunodeficiency virus (HIV) infection. Because the direct effects of opiates on HIV infection are difficult to determine epidemiologically, animal models of lentivirus infection are relied upon to study the effects of opiates in the absence of confounding factors. Morphine, the predominant metabolite of heroin, is used in most experimental systems examining heroin abuse. In this study, morphine treatment of feline immunodeficiency virus (FIV)-infected cats modeled a typical pattern of escalating drug use interspersed with withdrawals. Plasma cortisol levels were measured for evidence of stress associated with morphine withdrawal. In the morphine-treated cats, cortisol levels peaked at time points corresponding to morphine withdrawal and returned to baseline levels during treatment and several weeks after the final withdrawal. Morphine-treated cats displayed clear behavioral and physical signs of opiate exposure and evidence of withdrawal when the drug was stopped. Morphine-exposed cats did not experience enhanced severity of FIV-related disease; in fact, morphine demonstrated a protective effect on FIV-associated changes in brainstem auditory evoked potentials. Our research suggests that opiate exposure is unlikely to adversely affect the progression of acute lentivirus infection and might be beneficial in controlling associated neurological disease.

A comparison of clinical and evoked potential (VEP and median nerve SEP) evolution in patients with MS and potentially related conditions

A clinical and electrophysiological (VEP and median nerve SEP) follow-up was performed in 27 subjects selected among 200 consecutive patients previously examined by multimodality evoked potentials because of MS or potentially related conditions. The mean interval between the examinations was 20 months. There was a concordance between the clinical and electrophysiological evolution for the majority of examined pathways. However, alterations were more frequent for evoked potentials than for clinical symptomatology: six VEPs and 16 SEPs were changed compared to the initial recordings whereas clinical alterations occurred in one eye and 11 arms. Definitely contradictory evolutions were observed in only two arms (in one of the MS patients). Significant deteriorations between examinations occurred for two VEPs and two SEPs, although the recordings remained within normal limits. We conclude that evoked potential recordings are valuable for monitoring and that serial recordings may increase the number of abnormal findings.

Latency and amplitude abnormalities of the scalp far-field P14 to median nerve stimulation in multiple sclerosis. A SEP study of 122 patients recorded with a non-cephalic reference montage

The frequency and characteristics of P14 abnormalities were investigated in 122 patients with probable (68), or definite (54) multiple sclerosis by recording SEPs to median nerve stimulation with a non-cephalic reference montage. The most frequent SEP abnormality found in our series (62% of abnormal results) combined latency increase and amplitude reduction of P14. Interindividual variability, inherent in absolute amplitude measurements, was by-passed by calculating the ratio between the amplitudes of far-field P9 and P14 components, which proved to be normally distributed in controls. In spite of the strong association (P much less than 0.001) between the P9-P14 interpeak interval (IPL) and the P9/P14 amplitude ratio in MS patients, the latter parameter was found to be the only abnormality in 12 patients whose P9-P14 and P14-N20 IPLs were normal. Also IPLs were increased in 12 patients with normal P14 amplitudes. These results suggest that adding the P9/P14 amplitude criterion to standard IPL data might be useful to detect conduction troubles in MS patients.

Multiple sclerosis presenting at 4 years of age: clinical and MRI correlations

The authors present a patient with multiple sclerosis (MS) whose onset of illness was at 4 years of age. Three separate and distinct episodes of central nervous system (CNS) dysfunction associated with cerebrospinal fluid (CSF) pleocytosis, electroencephalographic (EEG) abnormalities, and extensive CNS white matter demyelination on both computerized tomography (CT) and magnetic resonance imaging (MRI) characterized her clinical course. Two episodes responded well to prednisone therapy.

Magnetic resonance imaging and clinical relationships in multiple sclerosis

Magnetic resonance imaging (MRI) was done in 109 patients with suspected demyelinating disease (56 with clinical multiple sclerosis [MS] and 53 without). Of those with clinical MS, 43 (77%) had multifocal lesions of the white matter detected on MRI; 12 of the 43 also had confluent periventricular signaling. Nine patients (17%) without clinical MS had similar findings. Of the 56 patients with MS, 35 underwent both computed tomography (CT) and MRI. In this group, 80% of MRI scans showed multiple demyelinating lesions compatible with MS, as compared with 29% of the CT scans. A CT scan was "positive" more often if obtained within 1 month after an attack of MS than later. In contrast, the sensitivity of MRI or the number of lesions detected by MRI did not increase in patients with recent exacerbations. MRI was "positive" in patients with clinical MS more often than was any single evoked response study. In statistical analyses, both the sensitivity of MRI and the number of lesions were associated with the duration of MS. A pattern of confluent periventricular signaling around the lateral ventricle was associated with greater duration of MS and patient disability.

Cerebral evoked potentials in multiple sclerosis

Multimodal evoked potentials were analyzed from 58 possible, 62 probable and 100 definite (total 220) multiple sclerosis (MS) patients. Visual evoked potentials (VEP) were most frequently abnormal yielding 39%, 69%, 84% in the three diagnostic groups respectively. Median nerve sensory evoked potentials (SEP) yielded abnormalities in 26%, 65%, 79% respectively. Brainstem auditory evoked responses (BAER) were abnormal in 17%, 39%, 66% respectively. We measured the combined amplitude (CA) of waves III, IV, V in the BAER of these patients as an objective measure of amplitude asymmetry. The CA was considered abnormal if it was 1SD below the lowest CA value in the control group. The CA was abnormal in 9.2% of BAER with normal central conduction time. The BAER diagnostic yield in MS patients increased 11% by using CA analysis.

Recurrent transverse myelitis associated with collagen disease

A 43-year-old woman who had four recurrences of acute transverse myelitis (ATM) at the fifth thoracic vertebral level in 7 years is reported. Her haematological and immunological abnormalities included antibodies to DNA and nRNP and markedly reduced serum complement during the course of the disease. These findings suggest systemic lupus erythematosus although she had no symptoms other than those of ATM. Methylprednisolone and prednisolone were effective in treating the ATM.

Some comments on the clinical use of evoked potentials

In this survey we describe the uses of somatosensory, visual, and auditory evoked potentials (EPs), adding some critical comments on the values and pitfalls of these methods. It must be stressed that the application of EPs is most valuable when combined with a thorough neurological examination. There is general agreement that EP measurement is one of the best techniques for objective, noninvasive study of brain function in humans.

Electrophysiological disorders in multiple sclerosis and optic neuritis

Visual evoked response (VER), auditory brainstem evoked response (ABER), somatosensory evoked response (SSER), blink reflex and electronystagmographic (ENG) investigative methods were applied to a group of 89 patients with Multiple Sclerosis (MS) and Optic Neuritis (ON). The MS patients were classified as definite (n = 31), probable (n = 31) and possible (n = 27). The aim of this study was to determine the diagnostic value of the five electrophysiological tests in MS. VER and ABER recordings were found to reveal the highest number of asymptomatic abnormalities (33 and 31 percent respectively). The combination of VER, ABER and ENG revealed all possible electrophysiological disorders. As these tests are completely non-invasive it is proposed, that a combination of two of these three tests is useful for the detection of a second silent lesion in patients with suspected MS showing purely spinal signs (VER, ENG, ABER) and/or a history of uncomplicated ON (ABER, ENG).

Multiple sclerosis in childhood: a new look

Five patients (four female, one male) with multiple sclerosis were managed at the Hospital for Sick Children, London, between January 1978 and June 1983. The age at which first symptoms occurred varied from three to 14 years. Focal seizures occurred in three cases and an encephalopathic process in three cases, and there was evidence of progressive intellectual deterioration in all five children. Computed tomography showed low-density lesions in the white matter of all five. Electroencephalograms were abnormal in all cases, and in two the disturbance was severe. Oligoclonal bands were present in the cerebrospinal fluid of two children. Four of the five children had abnormal responses to pattern-reversal stimulus.

The blink reflex and somatosensory evoked potential in optic neuritis in south India

Optic Neuritis (ON) proceeds to multiple sclerosis (MS) in a considerable number of patients. The blink reflex (BR) and somatosensory evoked potential (SSEP) are useful non-invasive tests that can detect silent lesions in the central nervous system in patients with clinically suspect MS. In the present study, the BR and SSEP were done in 20 healthy controls and 20 patients with ON. Abnormalities of the SSEP were seen in 20%, and of the BR in 30% of the patients with ON. On combining the results of SSEP and BR studies, 45% of the ON patients were seen to have abnormalities. Over a short period of follow-up, 2 of the 20 ON patients developed clinical MS and both of them had had abnormalities of the BR. These findings suggest that ON proceeding to MS in India may be more common than suspected at present.

Multiple sclerosis: incorporation of results of laboratory techniques in the diagnosis

In a retrospective study of 100 multiple sclerosis patients we compared the diagnostic classification according to the Schumacher/Rose criteria and the newest criteria, proposed by Poser et al. It is clear that by incorporating the results of laboratory investigations in the diagnostic criteria a firm diagnosis of multiple sclerosis can be reached more often and at an earlier stage of the disease. Evaluating abnormal laboratory findings, we found that it was possible to detect more than 90% of diagnostically important findings, i.e. findings effecting a change in diagnostic classification (from possible multiple sclerosis to probable or definite, from probable to definite), using only two of the laboratory tests: cerebrospinal fluid analysis and visual evoked response. Because the results of laboratory tests contributing to diagnostic classification are not specific for multiple sclerosis, the importance of evaluating the complete differential diagnosis of diseases that can be confused with multiple sclerosis is stressed.

Brain-stem auditory evoked responses (BAERs) in patients with chronic renal failure

Brain-stem auditory evoked responses have been investigated in 28 patients suffering from chronic renal failure (17 on diet, 11 on chronic dialysis) during monaural stimulation with 70 dB HL clicks. These responses were abnormal in 32.15% of cases. In 13 out of 15 years with altered BAERs a normal response morphology was present, with progressively more significant latency delays involving all peaks following wave I, while in the remaining two ears some of the components always found in healthy controls were not identifiable. The most prominent abnormality in patients with symptoms referable to peripheral neuropathy was the presence of a prolonged I-II interpeak latency, while in those without symptomatology the I-V and III-V interpeak times and the peak V latency were the most strikingly altered parameters. The incidence of altered BAERs was higher in the group of patients treated with diet than in the dialysed group. When BAERs were followed-up in the hours preceding and following the first dialysis in two patients not included in the previous group, the I-V interpeak time significantly decreased after 26 h from the end of dialysis.

Central nervous system involvement in optic neuritis

Thirty patients with clinically uncomplicated optic neuritis were subjected to a battery of electrophysiological tests, including visual evoked response (VER), auditory brainstem evoked response (ABER) and somatosensory evoked response (SSER). Blink reflex, electronystagmography (ENG), and computed tomography examinations were also carried out on all patients. These non-invasive tests indicated that in 11 of the 30 patients (37%), the optic neuritis was a symptom of subclinical multiple sclerosis, and that another five patients showed signs of mild central nervous system (CNS) involvement which may develop into multiple sclerosis later. This was confirmed by cerebrospinal fluid (CSF) analysis, using isoelectric focusing, showing oligoclonal extra bands in 11 out of these sixteen. A new classification of optic neuritis is proposed on the basis of these findings.

CT findings in acute MS

In 5 patients with definite or highly probable MS, unusually large hypodense plaques are seen by computerized tomography (CT scan). The active plaques all show enhancement after i.v. contrast medium injection, suggestive of blood-brain-barrier-damage, and differ from the well-known CT findings in chronic MS patients, causing diagnostic difficulties between glioma and infarction.