A sequential study of visual evoked potential in patients with vitamin B12 deficiency neurological syndrome.

OBJECTIVE: Visual pathways are vulnerable to vitamin B(12) deficiency but there is paucity of studies evaluating visual evoked potential (VEP) changes following vitamin B(12) supplementation. Our aim was to evaluate the visual evoked potential changes in patients with vitamin B(12) deficiency neurological syndrome and their changes after vitamin B(12) therapy. METHODS: Seventeen patients with vitamin B(12) deficiency neurological syndromes diagnosed on the basis of megaloblastic bone marrow or low serum vitamin B(12) level or both were subjected to testing of visual acuity, field of vision, colour vision and neurological examination. Cranial magnetic resonance imaging was done in 9 patients and pattern reversal VEP was carried out on admission. P(100) latency and amplitude were measured. Visual function and VEP studies were repeated at 3 and 6 months after vitamin B(12) therapy. RESULTS: The patients' age ranged between 17 and 69 years; 7 were females and 16 were lactovegetarians. The duration of symptoms ranged between 10 days and 10 years. Visual acuity, colour vision, field of vision and fundus oculi were normal. VEP revealed prolongation of P(100) latency in 10 patients (17 eyes) which was mild in 2, moderate in 10 and marked in 5 eyes. Six months after treatment, P(100) latency improved to normal in all except 4 eyes. VEP abnormality was related to duration of illness and antiparietal cell antibodies. CONCLUSIONS: VEP is frequently prolonged in patients with vitamin B(12) deficiency neurological syndrome although asymptomatic. It usually returns to normal after treatment.     

Serial pattern evoked potential recording in a case of toxic optic neuropathy due to ethambutol

Visual evoked potentials (VEPs) were studied in a patient who developed visual impairment during ethambutol treatment. The ERG and the flash VEP were normal at the time of maximal visual loss, whereas pattern reversal VEPs 2 and 5 months after onset revealed evidence of severe bilateral optic nerve involvement, especially affecting macular fibres. Seven months after onset paramacular PNP complexes with a late positivity (scotomatous response) were recorded after pattern reversal and half-field stimulation, suggesting involvement of fibres subserving central vision. At the time when visual acuity was normal there was still electrophysiological evidence of a mild involvement of the anterior visual pathway. The papillomacular bundle seems to be especially involved in ethambutol eye toxicity.     

Perimetry, visual evoked potentials and visual evoked spectrum array in homonymous hemianopsia

Confrontation field examination, perimetry, visual evoked potentials (VEPs) to pattern hemi-field stimulation and visual evoked spectrum array to flash stimulation were compared in 50 patients with homonymous hemianopsia. Visual field could be examined by confrontation in all patients and demonstrated the field defect in 96% of cases. Goldmann perimetry could only be performed in 60% of patients, but always quantitatively defined the margins of the defect. VEPs could only be tested in 77% of patients and demonstrated an abnormality in 79% of cases. VEPs were absent to stimulation of the affected hemifield in every case of homonymous field defects with macular splitting. Visual evoked spectrum array could be tested in 95% of patients and revealed abnormalities in 67% of cases. The relative value of each test is discussed.     

Evoked potentials during recovery from blindness recorded serially from an infant and his normally sighted twin

Visual evoked potentials (VEPs) elicited by diffuse field flashes wee recorded from a behaviourally blind infant with his twin as control. The patient was tested at ages 4, 5, 6, 8, 10 and 15 months. In spite of his behavioural blindness, clear VEPs were recorded from the patient at age 4 months, although the wave form was monophasic as contrasted with the multiphasic wave form recorded from his twin at the same age. Latency to first deflection and to first peak were considerably longer for the patient. The patient's VEP wave forM grew progressively more complex with age, paralleling recovery of useful vision. However, the VEP development anticipated behavioural recovery.     

Subclinical visual field defects in multiple sclerosis

Summary Fourteen patients with definite but inactive multiple sclerosis (MS) and 17 normal controls were examined with the automated perimeter octopus. Most of the patients had subclinical visual field defects, typically consisting of patchy, shallow scotomata located mostly in an area of between 15° and 30° eccentricity. In 8 patients, more than 15% of the tested visual field of at least one eye was abnormal. The severity and extent of the defects was unrelated to a history of optic neuritis. When visually evoked potentials (VEPs) of these subjects were examined using a reversing pattern, no correlation was found in the MS patients between prolonged VEP latencies and the location, depth or extent of visual field defects. Since subclinical visual field defects may be found in MS patients with normal VEP latencies, automated perimetry can be helpful in diagnosing some cases.Supported in part by Geigy Jubilaeumsstiftung, Basel     

Optic neuritis: a prospective study

We studied 20 patients with acute optic neuritis prospectively for 12 months. Visual fields, color vision, and VEPs to 15' checks were initially abnormal in all patients. Visual acuity was abnormal in 90% and contrast sensitivity in 95% of patients. We devised a graded visual impairment scale (GVIS) to include all visual functions tested. Complete recovery of visual function occurred in 65% of cases. Recovery in the majority of patients was rapid and complete within the first 2 months. In some patients, improvement continued over 6 months. The initial classification on the GVIS was significantly correlated with the final outcome. Patients initially classified as having moderate visual impairment recovered completely or improved to near normal vision. Sixty percent of patients initially classified as total or severe blindness had permanent visual impairment. VEP latency remained prolonged in 19 patients, even when their vision had returned to normal, and is a reliable indicator of resolved optic neuritis.     

Usefulness of multifocal VEP in a child requiring perimetry

We examined the reliability of multifocal visual evoked potentials for evaluating visual-field defects in a child with epilepsy and an arachnoid cyst. Multifocal visual evoked potentials were measured both when perimetry was difficult and several years later, when kinetic perimetry became possible in a child with epilepsy and homonymous hemianopia, as suggested by computed tomography of the brain. The peak latency and amplitude of response waves were used for assessment. The recordings of multifocal visual evoked potentials at both times revealed marked decreases in amplitude in the left visual hemifield. This area of decreased amplitude corresponded to the location of the lesion observed with imaging techniques, and was consistent with the left homonymous hemianopia observed via kinetic perimetry. The objective evaluation of visual-field defects through multifocal visual evoked potentials may be useful in children in whom conventional perimetry is difficult.     

应用视觉诱发电位术中监测视觉功能的研究

目的评价视觉诱发电位(VEP)在切除累及视路病灶的手术中监护视觉功能方面的可行性和可靠性。方法回顾分析31例累及视路病变的患者的临床资料,全静脉麻醉后手术,用2.1Hz的闪光二极管刺激患者,通过头皮(29例)或皮层(2例)记录视觉诱发电位,分析术中诱发电位的变化与术后视觉功能变化的关系。结果 25例患者描记出清晰、可重复的波形;VEP异常或消失的患者有7例,术后视力下降2例,视野缺损加重6例;8例术中出现VEP波形的异常,予及时改变手术策略,避免对视路的进一步骚扰后,2min内波形渐趋正常,术后仅有1例出现视野缺损。结论视觉诱发电位是一种能够提供实时视觉功能监测的可靠方法,能及时发现视路损伤。     

Partial recovery from cortical blindness following carbon monoxide intoxication

Patients with carbon monoxide (CO) intoxication may show neurological signs such as headache, seizures, extrapyramidal findings, and coma. However, cortical blindness is rare in these cases. This study describes a woman exhibiting confusion and axial rigidity after CO intoxication. Ten days after intoxication, her pupils were isonormocoric and reactive to light. A fundoscopic examination was normal, but visual acuity was light-perception in both eyes. There were diffuse EEG slow waves. Magnetic resonance imaging (MRI) demonstrated bilateral hyperintensity in the basal ganglia. The P100 latencies of visual evoked potentials (VEP) were increased and dispersed. One year later, the patient's visual acuity was almost normal and VEPs showed mild dispersion in P100 latencies. The authors found this case of interest because cortical blindness due to CO intoxication is only rarely seen with a relatively good outcome.     

Partial Recovery from Cortical Blindness Following Monoxide Intoxication

Patients with carbon monoxide (CO) intoxication may show neurological signs such as headache, seizures, extrapyramidal findings, and coma. However, cortical blindness is rare in these cases. This study describes a woman exhibiting confusion and axial rigidity after CO intoxication. Ten days after intoxication, her pupils were isonormocoric and reactive to light. A fundoscopic examination was normal, but visual acuity was light-perception in both eyes. There were diffuse EEG slow waves. Magnetic resonance imaging (MRI) demonstrated bilateral hyperintensity in the basal ganglia. The P100 latencies of visual evoked potentials (VEP) were increased and dispersed. One year later, the patient's visual acuity was almost normal and VEPs showed mild dispersion in P100 latencies. The authors found this case of interest because cortical blindness due to CO intoxication is only rarely seen with a relatively good outcome.     

Results of static perimetry in subclinical optic neuritis in multiple sclerosis

Static perimetry of the central visual field was performed using Harms apparatus and Friedmann's analyser in 20 M.S. patients with subclinical optic neuritis at least for one eye. Sub-clinical optic neuritis was defined as delayed or absent pattern reversal visual evoked potentials (VEPs) associated with normal routine ophthalmological examination (visual acuity, optic fundi, colour vision, kinetic perimetry). Results in patients were compared to data obtained in 22 control subjects, matched for age. A highly significant loss of mean retinal sensitivity was observed in the 20 central degrees of the visual field of eyes with abnormal VEPs. Central relative scotomata were disclosed in 18 of the 33 eyes with abnormal VEPs. Static perimetry was found to be abnormal, for at least one eye, in 15 in the 20 M.S. patients. Thus abnormal VEPs in M.S. are often associated to a lowered capacity to detect a stationary stimulus in the central visual field. The Friedmann's visual field analyser allows a quick and reliable evaluation of the loss of retinal sensitivity in M.S. patients.     

Visual evoked potentials in Reye's syndrome.

Visual evoked potentials (VEPs) induced by flash stimulation in a child who was recovering from Reye's syndrome with complaints of poor left-eye vision were recorded. Ophthalmological examination disclosed intact visual fields and normal visual acuity. Analysis of VEP's, however, showed a grossly abnormal configuration of wave forms, marked prolongation in latency and reduction in amplitude when the left eye was stimulated. Follow-up observation 3 weeks later showed parallel improvements in VEPs and subjective complaints. Thus, from VEP analysis, it may be possible to detect subtle changes in the visual system that have diagnostic and prognostic value.     

Relation between neurological status, refractive error, and visual acuity in children: a clinical study

The aims of the present study were: (1) to determine the refractive status and visual acuity of a group of 75 neurologically impaired children (5 to 192 months of age); and (2) to investigate the relation between the visual and neurological status of these children. Refractive error was determined using non-cycloplegic near retinoscopy and visual acuity was estimated using acuity cards (Keeler or Cardiff) and pattern-onset visual evoked potentials (VEP). Subjects demonstrated a markedly different distribution of refractive error from that of a neurologically normal age-matched population. Refractive error anomalies were more prevalent in children older than 5 years, suggesting abnormal refractive development. A wide range of visual acuity was found with both tests (acuity cards, 0.07 to 2.08 logMAR; VEP, 0.78 to 2.68 logMAR). Visual acuity and refractive status varied with level and type of physical impairment. Level of intellectual impairment exhibited a weak relation with visual status.     

A child with epilepsy in whom multifocal VEPs facilitated the objective measurement of the visual field

PURPOSE: We investigated whether visual field defects can be objectively evaluated by using multifocal visual evoked potential (multifocal VEP) in children with epilepsy in whom it is difficult to measure the visual field. METHODS: First, to determine normal waves in multifocal VEP, recording was performed by using a VERIS Junior Science (Mayo, Aichi, Japan) in 21 healthy children (21 eyes) consisting of 12 boys and nine girls aged 6 to 15 years (mean age, 11.4 years). Responses from eight sites in each subject were divided into four quadrants (superior and inferior temporal quadrants and superior and inferior nasal quadrants). In each quadrant, two response waves were grouped and averaged; peak latency and amplitude were used for assessment. In a child with epilepsy in whom kinetic or static perimetry was impossible, multifocal VEPs were recorded and compared with the peak latency and amplitude in the healthy subjects. RESULTS: In the 21 healthy children, no significant differences were observed in the peak latency or amplitude among four quadrants by one-way analysis of variance. Multifocal VEPs in the child with epilepsy showed abnormal waves in the right hemivisual field, which corresponded to the lesion observed with magnetic resonance imaging. CONCLUSIONS: The objective evaluation of visual field defects by using multifocal VEP may be useful in children with epilepsy in whom kinetic/static perimetry as a subjective examination is difficult.     

Behavioural and electrophysiological measures of visual functions in children with neurological disorders

The preferential looking (PL) technique, pattern visual evoked potentials (VEPs) and (simple) tests for visual field size were used to assess visual functions in 37 children with neurological disorders, ranging in age from 10 weeks to 15 years. PL acuities were obtained for 23 out of 32 patients tested (70%). Acuity was nearly always lower than normal, which often, but not always, was related to ophthalmological or neurological defects. Pattern VEPs were recorded in 7 patients. In 3 out of 4 patients, VEP 'acuity' was much lower than PL acuity, possibly due to spontaneous eye movements. One of two cortically blind children had positive pattern VEPs. Visual field defects were seen in 21 out of 23 children tested with a simple method using a pair of white balls. In only one-third of these, the field defects could have been predicted by the neurological and/or ophthalmological conditions. In several cases, field size appeared to be affected by spontaneous and/or latent nystagmus. A simplified perimeter has been found very useful with children from the age of 4 years onwards.     

神经内镜经鼻入路手术治疗颅咽管瘤的疗效评价

目的探讨神经内镜经鼻入路手术治疗颅咽管瘤的临床疗效。方法回顾性分析2018年10月至2020年4月首都医科大学附属北京天坛医院神经外科采用神经内镜经鼻入路治疗102例颅咽管瘤患者的临床资料,其中原发肿瘤82例,复发肿瘤20例。术后每3个月门诊随访患者的视力、视野,评估垂体-靶腺轴损伤数量以及有无尿崩症,复查头颅MRI观察肿瘤有无复发、进展。根据术后3个月的头颅MRI结果,评估肿瘤的切除程度结果102例患者中,92例(90.2%)肿瘤全切除,10例(9.8%)次全切除;其中原发肿瘤全切除77例,复发肿瘤全切除15例术后5例患者发生脑脊液漏并行神经内镜经鼻修补术,3例患者发生中枢神经系统感染。无一例患者死亡或出现昏迷。102例患者随访时间的中位数(范围)为12(6~19)个月。至末次随访,96例术前视力、视野受损的患者中,62例视力明显改善,27例稳定,7例恶化;术前视力正常的6例患者中,仅1例术后视力短暂下降,术后3个月复查时视力恢复正常。99例合并尿崩症,其中72例尿崩症持续时间≤3个月,27例持续时间>3个月至末次随访,73例术前存在垂体-靶腺轴功能障碍的患者,垂体-靶腺轴功能均无改善;29例术前垂体-靶腺轴功能正常的患者中,22例出现垂体-靶腺轴功能障碍102例患者随访期间复查头颅MRI均未见肿瘤复发或进展。结论采用神经内镜经鼻入路手术可更充分地观察肿瘤与视神经、垂体柄及下丘脑等结构的界限,为术者提供更清晰的术野,肿瘤全切除率较高,部分患者术后视力、视野改善,但术后尿崩症和垂体-靶腺轴功能障碍发生率较高。     

Blindness following pituitary apoplexy: Timing of surgery and neuro-ophthalmic outcome

The aim of this study is to report the neuro-ophthalmic outcome in patients who underwent transsphenoidal decompression for unilateral or bilateral blindness that was due to pituitary apoplexy. Four patients who were rendered blind (with an absence of light perception) unilaterally or bilaterally as a result of pituitary apoplexy were studied. Neuro-ophthalmic evaluation was performed pre- and post-operatively. Patients underwent CT and MRI pre-operatively and CT post-operatively. All four patients underwent transethmoidal decompression of the pituitary adenoma. One patient underwent a second transcranial procedure to remove the remaining suprasellar component of the tumor. Visual acuity, visual fields and extra-ocular movements were documented during the follow-up period. There were three males and one female. Ages ranged from 40 to 68 years. Three patients had unilateral blindness and one was blind in both eyes. Two of the four patients had associated ophthalmoplegia. All the four patients presented within one week of ictus. One patient underwent surgery within the first week, two patients underwent surgery two and three weeks after ictus and the other patient underwent surgery two months after ictus. The patient who was operated on within the first week recovered from bilateral blindness to a visual acuity of 6/9 and 6/12 with superior quadrantic field defects. The two patients who were operated on two and three weeks after ictus improved to 6/60 in the affected eyes and the patient who was operated on after two months improved to 1/60 in the affected eye. Both the patients with ophthalmoplegia improved completely even though the surgery was delayed by two months for one patient. Although blindness following pituitary apoplexy is rare, visual acuity improves in most patients following transsphenoidal surgery. Early surgery within the first week after ictus leads to excellent visual outcome when compared with surgery that is performed at a later stage. In contrast to visual outcome, ophthalmoplegia improves even if surgical decompression is delayed.     

Visual defects in children after cerebral hypoxia

Visual functions were examined in 18 survivors of perinatal hypoxia/ischemia with mild to severe neurological sequelae, aged between 3 months and 17 years, and in two patients, aged 8 and 13 years, who had suffered postnatal hypoxic events. All but two patients showed clear visual deficits ranging from mild defects in visual acuity, visual field size, and/or optokinetic nystagmus to blindness. In 5 patients, the visual field was restricted to tunnel vision, a finding which appeared to be specifically related to the hypoxic/ischemic nature of the brain damage. The severity of the visual defects after perinatal hypoxia was related to the occurrence of neonatal seizures, later neurological outcome, and gestational age at birth. This is discussed in relation to previous studies of the effects of perinatal hypoxia/ischemia.     

视神经损伤经颅视神经管减压与视觉诱发电位的临床研究

目的探讨视神经损伤患者经颅视神经管减压治疗的临床疗效。方法回顾性分析经颅视神经管减压治疗的视神经损伤患者35例临床资料,3个月后复查视力及视觉诱发电位(VEP)检查。结果经颅神经管减压术后患者视力大部分改善;术前无光感患者术后视力恢复差;术后患者VEP的P100潜伏期延长、波幅降低,无光感患者波幅下降最明显。结论经颅神经管减压治疗有效,术前无光感患者手术效果差,术后VEP异常明显,VEP评价客观有效,与临床一致。     

Visual acuity and pattern of visual field loss at presentation in pituitary adenoma

Our purpose was to analyse the demographics, prevalence and pattern of visual field defects in patients with pituitary adenoma. We prospectively recruited 103 consecutive patients (206 eyes) presenting to a neurosurgical unit with pituitary adenoma. Ophthalmological examination and standard automated perimetry (Humphrey, 24-2 threshold) was performed. Severity of visual field defects was also assessed. The mean population age was 53.9 years (standard deviation = 15). Visual loss was the most common reason for presentation (39%) followed by endocrine abnormality (21%) and headache (15%). Patients with endocrine abnormality on presentation were 10.9 years younger than those presenting with visual loss (p = 0.001). Bitemporal defects were the most prevalent pattern (n = 22, 41%) followed by homonymous defects (n = 7, 13%). Of the patients with visual field loss, 33% had unilateral visual field defects. The mean visual acuity in those with bitemporal defects was 6/7.5 with half of these patients having 6/6 vision in both eyes. In conclusion, the majority of patients with pituitary adenoma have visual acuity better than 6/7.5 despite having visual field defects. While a bitemporal pattern of visual field loss is the most common, a significant proportion of patients had unilateral and altitudinal defects. Assessment of the visual field is essential to rule out chiasmal compression.