Alexia without agraphia in multiple sclerosis: case report with magnetic resonance imaging localization

The syndrome of alexia without agraphia occurs rarely in multiple sclerosis (MS). We report a patient with right homonymous hemianopsia and alexia without agraphia as his initial manifestations of relapsing-remitting MS. Magnetic resonance imaging (MRI) demonstrated a hyperintense lesion in the left occipital subcortical white matter (WM) and an enhancing lesion in the splenium of the corpus callosum. The clinical presentation and MRI findings were consistent with disconnection of the functional right occipital visual cortex from structures responsible for language comprehension in the left hemisphere. The diagnosis of MS was confirmed by subsequent development of additional periventricular WM lesions.

Treatment for Alexia With Agraphia Following Left Ventral Occipito-Temporal Damage: Strengthening Orthographic Representations Common to Reading and Spelling

PURPOSE

Damage to left ventral occipito-temporal cortex can give rise to written language impairment characterized by pure alexia/letter-by-letter (LBL) reading, as well as surface alexia and agraphia. The purpose of this study was to examine the therapeutic effects of a combined treatment approach to address concurrent LBL reading with surface alexia/agraphia.

METHOD

Simultaneous treatment to address slow reading and errorful spelling was administered to 3 individuals with reading and spelling impairments after left ventral occipito-temporal damage due to posterior cerebral artery stroke. Single-word reading/spelling accuracy, reading latencies, and text reading were monitored as outcome measures for the combined effects of multiple oral re-reading treatment and interactive spelling treatment.

RESULTS

After treatment, participants demonstrated faster and more accurate single-word reading and improved text-reading rates. Spelling accuracy also improved, particularly for untrained irregular words, demonstrating generalization of the trained interactive spelling strategy.

CONCLUSION

This case series characterizes concomitant LBL with surface alexia/agraphia and demonstrates a successful treatment approach to address both the reading and spelling impairment.

How low can you go: spatial frequency sensitivity in a patient with pure alexia

Pure alexia is a selective deficit in reading, following lesions to the posterior left hemisphere. Writing and other language functions remain intact in these patients. Whether pure alexia is caused by a primary problem in visual perception is highly debated. A recent hypothesis suggests that a low level deficit - reduced sensitivity to particular spatial frequencies - is the underlying cause. We tested this hypothesis in a pure alexic patient (LK), using a sensitive psychophysical paradigm to examine her performance with simple patterns of different spatial frequency. We find that both in a detection and a classification task, LK's contrast sensitivity is comparable to normal controls for all spatial frequencies. Thus, reduced spatial frequency sensitivity does not constitute a general explanation for pure alexia, suggesting that the core deficit in this disorder is at a higher level in the visual processing stream.

[Alexia without agraphia; not being able to read what you have just written]

BACKGROUND

Alexia without agraphia is a neurological syndrome that is caused by a specific lesion in the left (or the dominant) cerebral hemisphere. It is characterised by a severe reading disorder with writing ability intact.

CASE DESCRIPTION

We describe a patient who, after a fall from a staircase, could no longer read, even that which he had written shortly before. Initially, he also had problems with orientation and facial recognition. Two months after the accident, alexia without agraphia was still manifest while the other symptoms had disappeared. His ability to read showed a slow improvement; complete recovery occurred after two years. The absence of concomitant disorders was exceptional.

CONCLUSION

The disorder alexia without agraphia seems improbable, but deserves serious attention to prevent diagnostic delay.

Alexia without agraphia

Alexia without agraphia (also called pure alexia or word blindness) was the first of the disconnection syndromes (syndromes caused by disconnection of the right from the left cerebral hemisphere through interruption of the communication pathways between them) to be described. Déjerine in 1892 reported a patient who developed this syndrome after an infarct of the left occipital lobe and splenium of the corpus callosum. We describe a patient who developed alexia without agraphia due to an embolic left occipital lobe infarct extending to the posterior commissure and splenium of the corpus callosum.

[Development of pure alexia due to a lesion in the left fusiform gyrus in a patient with hypertrophic pachymeningitis]

We present the case of a patient with pure alexia due to a restricted lesion in the left fusiform gyrus. A 59-year-old right-handed female, with a 7-year history of rheumatoid hypertrophic pachymeningitis suddenly developed reading and writing difficulties. Neuropsychological examinations revealed the presence of alexia for both Japanese kanji (morphograms) and kana (phonograms); mild agraphia predominantly for kanji; and word-finding difficulty. Brain magnetic resonance imaging (MRI) revealed a high signal intensity lesion in the left fusiform gyrus on fluid attenuated inversion recovery (FLAIR) images in addition to marked thickness of the left cerebellar tentorium on contrast-enhanced T1-weighted images. The abnormal intensity lesion in the left fusiform gyrus was recognized as representing a cerebral edematous change due to venous insufficiency associated with dural thickness. After high-dose methyl-prednisolone therapy, there was a rapid improvement in the reading and writing abilities of the patient, and 5 days later all the symptoms had disappeared. Three months later, a repeat MRI showed that the abnormal intensity lesion in the left fusiform gyrus had disappeared completely. The present case suggests that damage to the left fusiform gyrus alone can cause pure alexia and mild agraphia. Furthermore, this case raises the possibility that the fusiform gyrus is a part of the writing center.

Large Acute Cerebral Hemorrhage Presenting With Pure Alexia

Alexia (the acquired inability to read) is an uncommon presenting complaint in the emergency department (ED). It is usually associated with a lesion in the brain located within the dominant hemisphere near the parieto-occipital junction, with some involvement of the splenium of the corpus callosum. Our review of the literature revealed multiple distinct causes for the finding of alexia, and a majority of the cases uncovered also involved agraphia (the acquired inability to write) and frequently visual field defects. We present the case of an otherwise healthy 35-year-old white man who arrived at our ED with the chief complaint of having difficulty reading. He was, however, able to write, and he exhibited no defects in his visual fields on gross testing in our ED. The patient was found to have a large, acute, intraparenchymal hemorrhage in the right posterior/inferior parietal cortex, very near the occipital lobe. We present this case, followed by a brief discussion, to heighten awareness of the complaint of alexia with or without agraphia as a possible presenting symptom of intracranial hemorrhage, or ischemic cerebrovascular accident.

Temporal processing deficits in letter-by-letter reading

Theories of the cognitive impairment underlying letter-by-letter reading vary widely, including prelexical and lexical level deficits. One prominent prelexical account proposes that the disorder results from difficulty in processing multiple letters simultaneously. We investigated whether this deficit extends to letters presented in rapid temporal succession. A letter-by-letter reader, G.M., was administered a rapid serial visual presentation task that has been used widely to study the temporal processing characteristics of the normal visual system. Comparisons were made to a control group of 6 brain-damaged individuals without reading deficits. Two target letters were embedded at varying temporal positions in a stream of rapidly presented single digits. After each stream, the identities of the two letters were reported. G.M. required an extended period of time after he had processed one letter before he was able to reliably identify a second letter, relative to the controls. In addition, G.M.'s report of the second letter was most impaired when it immediately followed the first letter, a pattern not seen in the controls, indicating that G.M. had difficulty processing the two items together. These data suggest that a letter-by-letter reading strategy may be adopted to help compensate for a deficit in the temporal processing of letters.

Structural anatomy of pure and hemianopic alexia

BACKGROUND

The two most common types of acquired reading disorder resulting from damage to the territory of the dominant posterior cerebral artery are hemianopic and pure alexia. Patients with pronounced hemianopic alexia have a right homonymous hemianopia that encroaches into central or parafoveal vision; they read individual words well, but generate inefficient reading saccades when reading along a line of text. Patients with pure alexia also often have a hemianopia but are more disabled, making frequent errors on individual words; they have sustained damage to a brain region that supports efficient word identification.

OBJECTIVE

To investigate the differences in lesion site between hemianopic alexia and pure alexia groups, as rehabilitative techniques differ between the two conditions.

METHODS

High-resolution magnetic resonance images were obtained from seven patients with hemianopic alexia and from six patients with pure alexia caused by a left occipital stroke. The boundary of each lesion was defined and lesion volumes were then transformed into a standard stereotactic space so that regional comparisons could be made.

RESULTS

The two patient groups did not differ in terms of damage to the medial left occipital lobe, but those with pure alexia had additional lateral damage to the posterior fusiform gyrus and adjacent tissue.

CONCLUSIONS

Clinicians will be able to predict the type of reading disorder patients with left occipital lesions have from simple tests of reading speed and the distribution of damage to the left occipital lobe on brain imaging. This information will aid management decisions, including recommendations for reading rehabilitation.

Fusiform type alexia: Pure alexia for words in contrast to posterior occipital type pure alexia for letters

OBJECTIVE

To clarify the behavioral differences between patients with pure alexia from different lesions.

METHODS

Two patients with pure alexia caused by damage to the fusiform or posterior occipital gyri were given reading and writing tests including kanji (Japanese morphograms) and kana (Japanese phonetic writing).

RESULTS

Patient 1 (pure alexia from a fusiform gyrus lesion) had difficulty reading both kanji and kana, with kanji reading more impaired, and imageability and visual complexity effects (imageable or less complex words/characters were read better than nonimageable or more complex words/characters), whereas patient 2 (pure alexia from a posterior occipital gyri lesion) showed selective impairment of kana reading.

CONCLUSION

Pure alexia for kanji (and kana; fusiform type) is characterized by impairments of both whole-word reading, as represented in kanji reading, and letter identification, and is different from pure alexia for kana (posterior occipital type) in which letter identification is primarily impaired. Thus, fusiform type pure alexia should be designated pure alexia for words, whereas posterior occipital type pure alexia should be designated pure alexia for letters.

[Pure alexia secondary to progressive multifocal leukoencephalopathy as first manifestation of HIV infection]

INTRODUCTION

Pure alexia, or alexia without agraphia, is usually caused by disconnection between the gyrus angularis and visual areas of both hemispheres. Cerebrovascular disease is the most frequent cause of this syndrome.

CLINICAL CASE

We report the first case of a patient with pure alexia secondary to progressive multifocal leukoencephalopathy (PML) as the first manifestation of Human Immunodeficiency Virus (HIV) infection. Polymerase chain reaction in cerebrospinal fluid was positive for JC virus. Despite favorable immunological and virological response to highly active antiretroviral therapy, neurological symptoms and demyelinating lesions progressed during the first months, and right homonyous hemianopsia, acalculia, and color anomia were noted. In magnetic resonance imaging (MRI) demyelinating lesions involved white matter of both occipital lobes, with left predominance, forceps major and splenium of the corpus callosum, together with white matter of the left temporal lobe and both hippocampal regions. During the following months, coinciding cidofovir treatment, the patient had partial clinical improvement, but neurological deficits persisted. The size of MRI lesions significantly improved.

CONCLUSIONS

PML is frequently the first manifestation of AIDS (acquired immunodeficiency syndrome). It should be considered as a possible diagnosis of pure alexia.

Alexia without agraphia following cerebral venous thrombosis associated with protein C and protein S deficiency

A 26-year-old right handed female was admitted to hospital with right homonymous hemianopia associated with alexia without agraphia. Her cranial magnetic resonance imaging and magnetic resonance angiography revealed a left occipital venous infarction due to thrombosis of the left transverse, sigmoid sinuses and the left internal jugulary vein. The underlying conditions were protein C and protein S deficiency associated with the use of oral contraceptives. To our knowledge, alexia without agraphia has never been described due to a venous infarction associated with hereditary thrombophilia in the literature.

Transitory alexia without agraphia: a disconnection syndrome due to neurocysticercosis

We describe a 65-year-old male who presented with acute onset inability to read, without any difficulty in writing. A clinical diagnosis of alexia without agraphia was made and the patient was subjected to routine investigations including contrast MRI. MRI showed a ring-enhancing lesion in left occipital area, suggestive of neurocysticercosis supported by quantitative enzyme-linked immunosorbant assay from purified cell fraction of taenia solium cysticerci (PCF-ELISA). Patient was treated with albendazole and prednisolone for one week. The clinical manifestation as well as the radiological finding resolved after treatment.

Alexia without agraphia following biopsy of a left thalamic tumor

Alexia without agraphia is a rare disconnection syndrome characterized by the loss of reading ability with retention of writing and verbal comprehension. We report a patient who developed alexia without agraphia after undergoing a biopsy for a malignant glioma involving the left thalamus. A 15-year-old right-handed male presented with 3 days of severe headache, and vomiting, and 1 month of blurry vision in his right visual field. Magnetic resonance imaging of the brain disclosed a large exophytic mass originating in the left thalamus, with mass effect and hydrocephalus. The patient underwent biopsy of the left thalamic mass via a transcallosal approach. Postoperatively, the patient complained of inability to read or identify letters. Examination revealed alexia without agraphia. The syndrome of alexia without agraphia can be rarely caused after surgery. A transcallosal procedure through the splenium of the corpus callosum may disrupt the visual association fibers traveling from the right occipital cortex to the left angular gyrus. In our case the syndrome occurred because of a preexisting right homonymous hemianopia resulting from a left thalamic tumor.

The functional anatomy of single-word reading in patients with hemianopic and pure alexia

We investigated single-word reading in normal subjects and patients with alexia following a left occipital infarct, using PET. The most posterior brain region to show a lateralized response was at the left occipitotemporal junction, in the inferior temporal gyrus. This region was activated when normal subjects, patients with hemianopic alexia and patients with an incomplete right homonymous hemianopia, but no reading deficit, viewed single words presented at increasing rates. This same area was damaged in a patient with pure alexia ("alexia without agraphia") and no hemianopia, who read words slowly using a letter-by-letter strategy. Although the exact level of the functional deficit is controversial, pure alexia is the result of an inability to map a percept of all the letters in a familiar letter string on to the mental representation of the whole word form. However, the commonest deficit associated with "pure" alexia is a right homonymous field defect; an impairment that may, by itself, interfere with single-word reading because of inability to see the letters towards the end of a word. The relative contributions of pure and hemianopic alexia in individual patients needs to be assessed, as the latter has been shown to respond well to specific rehabilitation programmes.