Occipital lobe dysfunction revealed by functional brain imaging in a patient with traumatic visual field loss

We report a patient with visual field loss due to closed head trauma who was imaged with anatomic and functional brain imaging. The findings of ophthalmologic examination were normal except for a complete homonymous hemianopia on the right, an incongruous homonymous hemianopia on the left, and right oculomotor palsy. The results of anatomic brain imaging, computed tomography, and magnetic resonance imaging (MRI) were unremarkable. However, single-photon emission computed tomography (SPECT) scan revealed marked hypoperfusion of the left occipital lobe and functional MRI showed a corresponding strikingly reduced response to visual stimuli in the left occipital lobe. Therefore, this patient is thought to have had dysfunction of the left occipital lobe. Functional brain imaging techniques, such as SPECT and functional MRI, can be helpful in the localization of the responsible lesions even when conventional neuro-imagings are nondiagnostic.     

Cerebral polyopia after recovery of homonymous hemianopia resulting from occipital lobe infarction

A 48-year-old man suffering from right occipital lobe infarction had left homonymous hemianopia. Six months later, his visual defect had recovered almost completely. He started to complain of diplopia. On ocular examination, he had intermittent bilateral monocular diplopia. The diplopia could not be eliminated with a pinhole goggle. There was no ocular abnormality that may have caused his diplopia. MR imaging showed encephalomalasia over the extrastriate visual cortex and intact primary visual cortex. Although rare, cerebral polyopia of occipital lobe lesion should be considered in the differential diagnosis of monocular diplopia.     

Occipital lobe infarction following cardiac ablation

A 60-year-old man presented with the chief complaint of seeing a blurred area just up and to the left of the center of his vision. The patient noted this visual field defect immediately after he awoke from a cardiac electrophysiologic study with a catheter ablation procedure. On neuro-ophthalmologic testing, a small scotoma was present superior and left of fixation in both eyes. MRI showed a small irregular area of abnormal signal in the right occipital lobe consistent with an ischemic lesion. To the best of our knowledge, this represents the first case report of a homonymous visual field defect secondary to an occipital lobe infarction following a cardiac catheter ablation procedure.     

Occipital lobe infarction following cardiac ablation

A 60-year-old man presented with the chief complaint of seeing a blurred area just up and to the left of the center of his vision. The patient noted this visual field defect immediately after he awoke from a cardiac electrophysiologic study with a catheter ablation procedure. On neuro-ophthalmologic testing, a small scotoma was present superior and left of fixation in both eyes. MRI showed a small irregular area of abnormal signal in the right occipital lobe consistent with an ischemic lesion. To the best of our knowledge, this represents the first case report of a homonymous visual field defect secondary to an occipital lobe infarction following a cardiac catheter ablation procedure.     

【In Press】Altered intrinsic functional connectivity of the primary visual cortex in youth patients with comitant exotropia: a resting state fMRI study

Comitant exotropia (CE) is often associated with impaired fusion and stereoscopic vision. Many previous studies demonstrated that the strabismus patients showed abnormalities of the function and morphology in whole brain. However, the understanding of the dysfunction in primary visual cortex in patients with comitant exotropia is limited. Our study aimed to evaluate the differences in the functional connectivity (FC) of the primary visual cortex (V1) between the youth CE patients and health subjects using resting functional MRI data. The CE patients showed significantly less FC in the left BA17 and left lingual gyrus /cerebellum posterior lobe, right middle occipital gyrus, left precentral gyrus/postcentral gyrus and right inferior parietal lobule/ postcentral gyrus. Our findings showed that comitant exotropia involves abnormal FC in primary visual cortex in many regions, which may underlie the pathologic mechanism of impaired fusion and stereoscopic vision in CEs.     

Bilateral Superior Altitudinal Hemianopia due to Bilateral Occipital Lobe Infarction

ABSTRACT

We report a 77-year-old man showing bilateral superior altitudinal hemianopia (BSAH) caused by bilateral occipital lobe infarction. The lesions existed into the lingual gyri and involved V1, V2 and V3 in the visual cortex on both sides. The location of the lesions correlated well with visual field defects in our patient. There have been 8 case reports of BSAH caused by occipital lobe lesions, however, the extent of the lesions inside the visual cortex was not evaluated in the previously reported patients. The analysis in our patient showed a close clinico-radiological correlation of BSAH.     

视觉刺激功能磁共振成像在枕叶病变患者中的初步应用

目的 观察枕叶病变患者患侧与健侧的功能磁共振成像（fMRI）特点，评价fMRI在视觉中枢功能性病变检查、枕叶肿瘤定位、手术入路选择以及切除范围方面的临床应用价值。设计 病例系列。研究对象 伴有同侧偏盲的视觉中枢功能性病变及单侧枕叶肿瘤患者各1例。方法 对上述2例患者应用自行设计的双眼棋盘格刺激（5Hz）行脑fMRI检查。所得数据应用SPM软件处理（P〈0．01），与Goldmann视野计检查结果相比较，验证视野损害与其大脑皮层投影改变的一致性。主要指标 统计参数图，脑激活图，激活脑区信号变化的时间曲线，与标准化T1像叠加的脑激活图。结果 在视觉刺激on时，枕叶视功能区激活；off时无信号；2例患者fMRI检查右侧视功能区激活明确，左侧视功能区无信号与视野检查双眼右半视野缺损相一致。结论 视觉刺激程序能够很好地引出视觉中枢fMRI；fMRI的检查结果与视野结果一致性较好；fMRI在视觉中枢功能性检查、枕叶肿瘤范围定位的确定方面有良好的临床应用前景。     

Visual areas and spatial summation in human visual cortex

Functional MRI measurements can securely partition the human posterior occipital lobe into retinotopically organized visual areas (V1, V2 and V3) with experiments that last only 30 min. Methods for identifying functional areas in the dorsal and ventral aspect of the human occipital cortex, however, have not achieved this level of precision; in fact, different laboratories have produced inconsistent reports concerning the visual areas in dorsal and ventral occipital lobe. We report four findings concerning the visual representation in dorsal regions of occipital cortex. First, cortex near area V3A contains a central field representation that is distinct from the foveal representation at the confluence of areas V1, V2 and V3. Second, adjacent to V3A there is a second visual area, V3B, which represents both the upper and lower quadrants. The central representation in V3B appears to merge with that of V3A, much as the central representations of V1/2/3 come together on the lateral margin of the posterior pole. Third, there is yet another dorsal representation of the central visual field. This representation falls in area V7, which includes a representation of both the upper and lower quadrants of the visual field. Fourth, based on visual field and spatial summation measurements, it appears that the receptive field properties of neurons in area V7 differ from those in areas V3A and V3B.     

Neuroimaging analysis of a case with left homonymous hemianopia and left hemispatial neglect

PURPOSE: To correlate the neuro-ophthalmological observations with the magnetic resonance images (MRI) and positron emission tomographic (PET) findings in a case with left homonymous hemianopia and left hemispatial neglect. CASE: A 57-year-old woman underwent surgery for a ruptured anterior communicating artery aneurysm. After she recovered consciousness, it was found that she had left homonymous hemianopia and left hemispatial neglect. Although the hemispatial neglect slowly improved, the homonymous hemianopia persisted. MRI and measurements of cerebral glucose metabolism by 2-fluoro-2-deoxy-D-glucose(FDG)-PET were performed 1 year later. RESULTS: MRI revealed infarctions on the medial surface of the frontal lobe, on the right medial surface of the occipital lobe, and global atrophy of the right cortical hemisphere. FDG-PET disclosed severe glucose hypometabolism in the entire right hemisphere. Glucose metabolism in the right occipital cortex was 61.1% of that in the homologous region on the left side, 62.8% in the right anterior cingulate gyrus, and 93.8% in the temporal-parietal-occipital junction. CONCLUSIONS: The low glucose metabolism in the right visual cortex explains the persistent left hemianopia, and that in the right anterior cingulate gyrus and the right temporal-parietal-occipital junction may be responsible for the left hemispatial neglect. The relatively mild damage in the right temporal-parietal-occipital junction explained the recovery of the neglect symptom. Measurements of regional cerebral glucose metabolism by PET are useful for determining the cause of cerebral visual dysfunction and its prognosis after a cerebral lesion.     

Visual Loss Secondary to Bioccipital Calcifications Associated with Coeliac Disease

ABSTRACT

The purpose of this paper was to present a case report of permanent visual loss secondary to occipital lobe calcifications in coeliac disease. A 58-year-old grave digger was referred by his work place occupational health and safety department for vision assessment. His past medical history included coeliac disease (CD) diagnosed 20 years previously, as well as an over 40-year history of poor vision that had not been investigated. Examination showed bilaterally decreased visual acuity of <6/60 and a right homonymous inferior quadrantanopia confirmed on automated perimetry. The optic discs appeared normal with no pallor or neuroretinal rim loss. Computed tomography (CT) and magnetic resonance imaging (MRI) scans revealed bilateral occipital calcifications. Diffusion tensor imaging showed reduced anisotropy and difficulty tracing the optic radiations to the occipital lobes. This is the first described case of visual loss secondary to occipital lobe calcifications in coeliac disease.     

Occipital lobe infarction after open heart surgery

The most common permanent neuro-ophthalmologic complication of cardiopulmonary bypass surgery is visual loss. Bilateral lower altitudinal visual field defects were documented in a patient who noted blurred vision following open heart surgery. A difference of opinion existed as to whether the field defects were due to retina-optic nerve or occipital lobe lesions. Two points are emphasized in this report: 1) the field defects were much easier to define on the tangent screen than on Goldman perimetry, and 2) occipital coronal high resolution CT scan confirmed bilateral upper bank calcarine cortex infarctions in this patient. Occipital coronal, thin-section, high-resolution computed tomographic scans are helpful in studying patients with occipital lobe visual field defects.     

Palinopsia Accompanied with Migraine Attack After Having Occipital Brain Abscess

Palinopsia is defined as persistence of recurrent visual images after the stimulus has been removed. A 55-year-old male patient with long-standing migraine history developed brain abscess in the right occipital lobe. The patient developed episodes of palinopsia accompanied with migraine attack after healing of occipital lesion. The phenomenon cannot be sufficiently explained with single risk factor, although occipital lesion and migraine are both known to cause palinopsia. We speculated that migrainous brain is not always symptomatic but may drive cortex sensitive for second insult, such as occipital brain lesion. The predisposition may contribute to appearance of palinopsia.     

儿童屈光参差性弱视立体视觉中枢区激活的fMRI研究

目的 利用血氧水平依赖性功能性磁共振成像(BOLD-fMRI)技术评价屈光参差性弱视儿童在规范弱视训练后,立体觉映射的脑皮层功能区的恢复情况.方法 自身前后对照研究.选择11例屈光参差性弱视初诊患儿,行任务态组块式(Blocks)设计的fMRI实验,在弱视治疗后1周、2周及4周时复查BOLD-fMRI.采用基于Matlab 7.12.0.635的SPM8软件包进行图像后处理,采用随机效应法分别获得各组脑皮层激活的矩阵数据,利用假设驱动法对各治疗阶段结果进行自身前后配对t 检验,获得治疗前后各组视皮层激活的差异数据.立体图像为计算机生成的随机点立体视觉检查图,通过配戴红蓝眼镜观察立体视图像,当识别立体视图像后迅速点按反馈键.结果 弱视训练至4周时,左侧枕叶(BA18)、枕中回(BA19)、边缘叶(BA19)及右侧枕叶舌回(BA17)和双侧顶上小叶(BA7)激活范围不同程度扩大,与治疗前的平均激活强度差异t值分别是1.636、1.902、1.727、1.350与1.777(P＜0.01),但增进幅度偏小,且与随机点立体视图的恢复不平行.结论 儿童屈光参差性弱视对立体觉映射的脑皮层功能损害严重、短期恢复困难.     

Altered intrinsic functional connectivity of the primary visual cortex in youth patients with comitant exotropia: a resting state fMRI study

AIM: To evaluate the differences in the functional connectivity (FC) of the primary visual cortex (V1) between the youth comitant exotropia (CE) patients and health subjects using resting functional magnetic resonance imaging (fMRI) data. METHODS: Totally, 32 CEs (25 males and 7 females) and 32 healthy control subjects (HCs) (25 males and 7 females) were enrolled in the study and underwent the MRI scanning. Two-sample t-test was used to examine differences in FC maps between the CE patients and HCs. RESULTS: The CE patients showed significantly less FC between the left brodmann area (BA17) and left lingual gyrus/cerebellum posterior lobe, right middle occipital gyrus, left precentral gyrus/postcentral gyrus and right inferior parietal lobule/postcentral gyrus. Meanwhile, CE patients showed significantly less FC between right BA17 and right middle occipital gyrus (BA19, 37). CONCLUSION: Our findings show that CE involves abnormal FC in primary visual cortex in many regions, which may underlie the pathologic mechanism of impaired fusion and stereoscopic vision in CEs.     

Achiasmia and unilateral optic nerve hypoplasia in an otherwise healthy infant

An 18-month-old white boy, observed by his parents at 1-2 months age to have poor visual attentiveness and nystagmus, underwent an ophthalmological evaluation. The patient also underwent unsedated 5-channel flash visual evoked potentials (VEP) and sedated electroretinogram (ERG) testing as well as magnetic resonance imaging (MRI) of the brain and orbits. The VEP in response to monocular stimulation demonstrated occipital asymmetry and was clearly suggestive of crossed asymmetry and also showed right optic nerve hypoplasia. The MRI and fundoscopic examinations supported the findings of achiasmia and probable optic nerve hypoplasia. The patient also had decreased Teller card visual acuity, nystagmus and a variable right esotropia. Neurological examination was normal. The ophthalmological and MRI findings in this 18-month-old male patient support the diagnosis of isolated non-decussating retinal-fugal fibre syndrome as well as hypoplasia of the optic nerve.     

Recovery of Visual Field Defect via Corpus Callosum in a Patient with Cerebral Infarct

Recovery mechanism of visual field defect in stroke patients has not been clearly elucidated. In this study, we report on a patient with a cerebral infarct who showed recovery of visual field defect via the corpus callosum, using diffusion tensor tractography (DTT) for optic radiation (OR). A 57-year-old male patient underwent conservative management for a cerebral infarct in the subcortical white matter of the right temporal lobe. Left homonymous hemianopsia was detected on the 2-week Humphrey visual field test. However, the patient showed improvement of hemianopsia with time; consequently, a left lower peripheral visual defect with the resolution of the upper and medial portions of the initial left hemianopia was observed on the 11-month Humphrey visual field test. Both 2-week and 11-month DTTs for the right OR showed a discontinuation between the right lateral geniculate nucleus (LGN) and the right OR. On 2-week DTT, the left OR was connected to the transcallosal fibres, and on 11-month DTT, these transcallosal fibres were elongated to the right primary visual cortex via the right posterior OR. The visual field defect in this patient appears to have recovered by the neural pathway originating from the left OR and terminating in the primary visual cortex via the transcallosal fibres and right distal OR. We believe that the results of this study may suggest one of the mechanisms for recovery of visual field defect following injury of OR in stroke patients.     

视路疾病患者脑功能性磁共振成像初步观察

目的 观察视路疾病患者视网膜拓扑投射的分布及脑功能性磁共振成像(fMRI)与视野检查结果的关系.方法 3例经病理检查确诊为垂体瘤和颅咽管瘤的鞍区占位患者(患者组)6只眼以及年龄24～30岁的3名健康志愿者纳入研究.患者组6只眼最佳矫正视力无光感～1.0;健康志愿者矫正视力1.0,除近视外无其他眼疾.受检者均无fMRI检查禁忌.常规行最佳矫正视力、直接和(或)间接检眼镜眼底检查,Octopus101电脑全自动视野计32程序策略趋势导向检查法行中心静态视野检查.fMRI检查采用GE signa VH/I 3.0T扫描机.视觉刺激占据12°视角,采用对比度接近100%的黑白棋盘格,背景为棋盘格的平均亮度,包括周期性扩张或收缩的环形刺激和顺时针或逆时针旋转的楔形刺激两种模式.功能图像采用梯度回波的平面同波序列的血氧水平依赖扫描序列,垂直于距状裂冠状位扫描,三维采集方式的扰相梯度回波序列矢状位采集高分辨率解剖结构数据.数据分析采用AFNI软件,并且应用Freesurfer进行皮层的分割、膨胀处理.结果 6只患眼中,视野颢侧缺损3只眼,颞上方缺损2只眼,不能完成检查1只眼.环形刺激的功能图像显示,枕叶视觉皮层产生了时相对应的激活图像,枕叶后极沿距状裂向前迁移对应黄斑中心区向周边视野的迁移.楔形刺激的功能图像显示,初级视觉皮层的极角拓扑投射的空间序列与视野相反.距状裂下方的视皮层主要对应对侧上方视野,距状裂上方主要对应对侧下方视野.刺激患眼不能诱导出与相应视野缺损相关的初级视觉皮层的激活,存在相应视觉皮层反应的减少.结论 fMRI检查结果与常规视野计检查的结果有很好的对应关系,可以反映视路疾病患者的视野缺损对应的皮层反应.     

Homonymous quadrantanopsia in a case of disproportional hydrocephalus caused by pneumocephalus

A 29-year-old man with a posterior fossa arachnoid cyst presented with headache. A shunt revision was performed following the diagnosis of a malfunction of a previously inserted cyst-peritoneal shunt. Four days later, he developed right lower homonymous quadrantanopsia with sparing of the temporal crescent of the right eye. MRI revealed pneumocephalus and disproportional hydrocephalus, with enlargement of the occipital horn of the left lateral ventricle. This ventricular enlargement had stretched the optic radiation and caused the visual field defect. Of the fibers associated with right vision passing along the left lateral ventricle, those for peripheral vision of the right eye were located medially. The perimetry of the patient corresponded to the characteristic sparing of the visual field defect when the superior wall of the occipital horn was selectively stretched. The mechanism of enlargement of the occipital horn was thought to be air disturbance of CSF outflow and amplified pulsation of the brain.     

Recurrent scintillating scotoma and homonymous hemianopia due to metastatic melanoma

Acute left homonymous hemianopia and recurrent scintillating scotoma occurred in a 43-year-old woman due to metastases from a cutaneous malignant melanoma that had been resected 5 years previously. Computed tomography initially demonstrated small, probably embolic, areas of occipital lobe infarction. Five months after the onset of her visual symptoms, massive cerebral hemorrhage occurred from a large right occipital lobe tumor that had not been present initially. Autopsy demonstrated malignant melanoma. Visual symptoms related to tumor embolization and/or cerebral hemorrhage may be the presenting features of metastatic cutaneous malignant melanoma.     

Peripheral homonymous scotomas from a cavernous angioma affecting fibers subserving the intermediate region of the striate cortex

PURPOSE: To report the case of a pure peripheral homonymous visual field defect and to delineate the representation of the visual field on the striate cortex. METHODS: Observational case report. Neuro-ophthalmologic and neuroimaging assessment of a patient with a cavernous angioma of the right parieto-occipital lobe. RESULTS: The patient had left homonymous scotomas located 40 degrees to 60 degrees from the vertical meridian. Neuroimaging indicated that the lesion was affecting the optic radiations at their termination in the intermediate portion of the striate cortex or the striate cortex itself. CONCLUSION: Homonymous field defects are typically located within 10 degrees of fixation. This patient had a peripheral homonymous field defect from damage to the intermediate striate cortex. Correlation of the neuroimaging findings in this case with the most commonly used maps of the representation of the visual field on the striate cortex suggests that none of the maps correctly predicts the location or extent of lesions that affect the intermediate portion of the cortex.