Bilateral Cerebral Lesions Research Articles

Tubercular Meningitis Mimicking Acute Disseminated Encephalomyelitis (ADEM)- A Case Report

Tuberculosis remains endemic in India, and its manifestation in the central nervous system (CNS) poses significant challenges in diagnosis and management. We present a rare case of a 65-year-old male with tubercular meningitis exhibiting atypical features of acute disseminated encephalomyelitis (ADEM). The patient presented with a month-long history of fever, severe headache, altered sensorium, and neurological signs including brisk reflexes, neck rigidity, and bilateral motor weakness. Initial investigations revealed elevated inflammatory markers and abnormal cerebrospinal fluid (CSF) findings consistent with tubercular meningitis. Despite negative CSF culture and nucleic acid amplification tests (NAATs) for Mycobacterium tuberculosis, the patient displayed characteristic asymmetrical bilateral cerebral lesions on MRI suggestive of ADEM. Given the diagnostic ambiguity and a high suspicion of CNS tuberculosis with concurrent ADEM, the patient was treated with anti-tubercular therapy (ATT) and a course of intravenous methylprednisolone followed by oral prednisolone. Subsequent clinical improvement prompted gradual tapering of prednisolone, leading to a full recovery at discharge. This case highlights the complexity of diagnosing CNS tuberculosis coexisting with ADEM, emphasizing the importance of a comprehensive clinical assessment and tailored therapeutic interventions in managing such intricate neurological presentations.

Rescue Endovascular Treatment to Prevent Neurological Deterioration in Acute Symptomatic Bilateral Vertebral Artery Occlusion.

Bilateral vertebral artery occlusive disease has been considered as a favorable condition with good collaterals. However, the prognosis of acute ischemic stroke secondary to symptomatic bilateral vertebral artery occlusion (BVAO) and endovascular treatment (EVT) has rarely been reported. We retrospectively selected patients with acute ischemic stroke admitted for symptomatic BVAO between January 2020 and February 2023. All patients with ischemic stroke were evaluated for ischemic lesion and arterial status using brain imaging and angiography. The prognosis of acute stroke with symptomatic BVAO was compared between EVT and conventional treatment. Outcomes were evaluated using modified Rankin Scale (mRS) score at 3 months follow-up. Within the study period, 17 of 2,655 acute ischemic stroke patients were diagnosed with ischemic stroke with symptomatic BVAO. The median age of these patients was 70 (interquartile range 44-89) years, and 13 (76%) were male. Seven patients received emergent EVT with stenting and 10 patients received conventional medical treatment only. Nine of 10 patients with conventional treatment had in-hospital stroke progression and developed new ischemic lesions in the pons and midbrain. Five patients with fetal and hypoplastic posterior communicating artery presented bilateral cerebral peduncular lesions. At 3 months follow-up, 6 patients (35%) had favorable outcomes (mRS 0-2), of which 5 were treated with vertebral artery stenting and 1 received conventional treatment. Ischemic stroke in patients with acute symptomatic BVAO is uncommon. However, stroke progression is common, and the prognosis of most patients is poor. Rescue management such as EVT might be considered for symptomatic BVAO.

Different patterns of failure in two treatment regimens for primary central nervous system lymphoma, a retrospective analysis of 124 cases in Taiwan

To explore prognostic factors and outcomes of primary central nervous system lymphoma (PCNSL) of diffuse large B-cell lymphoma (DLBCL) in Taiwan, 124 PCNSL-DLBCL patients (from 1995 to 2021) were retrospectively analyzed. Mainly, two treatment modalities including sandwich chemoradiotherapy and modified MATRix regimen were employed in these patients. Overall survival (OS) was determined by log-rank test and time-dependent Cox analysis. Median OS of all patients was 27.1 months. 47 (37.9%) patients who underwent sandwich chemoradiotherapy had a complete remission (CR) rate of 87.2%, median OS of 53.9 months, and progression free survival (PFS) of 42.9 months. 11 (8.9%) patients who underwent modified MATRix regimen had CR rate of 72.7%, median OS of 18.9, and PFS of 11.2 months. There are no significant OS differences between treatment groups or addition of Rituximab. Patients treated with the modified MATRix regimen experienced a higher early mortality rate followed by a survival plateau. IELSG low-risk group had significantly improved OS and PFS than IELSG intermediate- or high-risk group. In multivariant analysis, age > 60 years old and bilateral cerebral lesions are associated with significantly inferior OS. Sandwich chemoradiotherapy demonstrated better early survival and reduced treatment-related toxicity for PCNSL patients compared to the modified MATRix regimen. However, the long-term follow-up revealed a higher rate of treatment failure events in the sandwich chemoradiotherapy group. IELSG and MSKCC scores served as reliable risk assessment models. Incorporating bilateral cerebral lesions as a risk factor further improved risk evaluation.

A case of Pathological Laughter in a patient with recurrent stroke

Introduction Stroke survivors frequently deal with neuropsychiatric sequelae - depression, anxiety and apathy being the most common ones. Pathological laughing and crying (PLC) is a post stroke condition characterized by brief, intense uncontrollable crying and/or laughing due to a neurological disorder. Prevalence of PLC post stroke has been reported to be 15-20%. Pathological laughter (PL) is commonly associated with bilateral or diffuse cerebral lesions. Ischemic injury involving the internal capsule and basal ganglia seems to be associated with emotional disorders. Objectives To discuss an uncommon case of pathological laughter developing after recurrent infarct. Methods A 32-year-old male patient presented to the medical emergency for complaints of slurring of speech since 7 hours. On examination, patient was alert, oriented, with blood pressure 150/90 mmHg. He had a history of similar stroke 2 years prior to current complaints and was on treatment for hypertension since then. Baseline investigations were done. MRI brain revealed acute lacunar infarcts in bilateral ganglio-capsular region, chronic small vessel ischaemic changes in B/L periventricular white matter (Fazeka grade 2) and micro-haemorrhages in various brain regions. Patient was managed conservatively (antiplatelets, statins, antihypertensives). Patient was then referred to Psychiatry department for uncontrollable laughing spells, which started few hours after onset of above complaints. These occurred without any provocation, every 1-2 hours, lasting for several seconds to a minute, and relieved spontaneously. Patient was aware of episodes and found them embarrassing socially. Mental status examination revealed no mood features or other abnormalities. Patient was prescribed Escitalopram, but shifted to homeopathic medicine and was lost to follow up. Telephonic interview one year later revealed that while other complaints have remitted, patient still has laughing spells of similar quality and frequency. Results Discussion: In post stroke PLC, pathological crying represents about 80% cases, while Pure Pathological Laughing, as in the present case, is uncommon. It is generally seen in diffuse CNS pathologies (eg. multiple sclerosis) or bilateral – ischaemic or degenerative. In case of strokes, PL may herald symptom onset, or may immediately follow focal deficits. The aetiology of PLC is unknown; monoaminergic neurotransmission may be altered in post stroke PLC. SSRIs are regarded as first choice treatment agents, given their greater tolerability overall. Conclusions Pathological laughter is a comparatively uncommon but recognisable and treatable post stroke sequela, more commonly seen in bilateral lesions. Patients often describe PL as distressing and socially disabling, but awareness about this condition and available treatments is lacking. Disclosure of Interest None Declared

Predictive Factors of Swallowing Disorders and Bronchopneumonia in Acute Ischemic Stroke

Background: In stroke patients, early complications such as swallowing disorders (SD) and bronchopneumonia (BP) are frequent and may worsen outcome. The aim of this study was to evaluate the prevalence of SD in acute ischemic stroke (AIS) and the risk of BP, as well as to identify factors associated with these conditions. Methods: We retrospectively studied all AISs over a 12-month period in a single-center registry. We determined the frequency of SD in the first 7 days and of BP over the entire hospital stay. Associations of SD and BP with patient characteristics, stroke features, dental status, and presence of a feeding tube were analyzed in multivariate analyses. Results: In the 340 consecutive patients, the overall frequency of SD and BP was 23.8% and 11.5%, respectively. The multivariate analyses showed significant associations of SD with NIHSS scores >4, involvement of the medulla oblongata and wearing a dental prosthesis (area under the receiver-operator curve (AUC) of 76%). BP was significantly associated with NIHSS scores >4, male sex, bilateral cerebral lesions, the presence of SD, and the use of an enteral feeding tube (AUC 84%). In unadjusted analysis, unfavorable 12-month outcome and mortality were increased in the presence of SD. Conclusion: In AIS, SD and BP are associated with stroke severity and localization and wearing a dental prosthesis increases the risk of SD. Given that patients with SD have an increased risk of poor outcome and mortality, high-risk patients warrant early interventions, including more randomized trials.

Acute Neurologic Disorder from an Inhibitor of Fatty Acid Amide Hydrolase

BackgroundA decrease in fatty acid amide hydrolase (FAAH) activity increases the levels of endogenous analogues of cannabinoids, or endocannabinoids. FAAH inhibitors have shown analgesic and antiinflammatory activity in animal models, and some have been tested in phase 1 and 2 studies. In a phase 1 study, BIA 10-2474, an orally administered reversible FAAH inhibitor, was given to healthy volunteers to assess safety.MethodsSingle doses (0.25 to 100 mg) and repeated oral doses (2.5 to 20 mg for 10 days) of BIA 10-2474 had been administered to 84 healthy volunteers in sequential cohorts; no severe adverse events had been reported. Another cohort of participants was then assigned to placebo (2 participants) or 50 mg of BIA 10-2474 per day (6 participants). This report focuses on neurologic adverse events in participants in this final cohort. A total of 4 of the 6 participants who received active treatment consented to have their clinical and radiologic data included in this report.ResultsAn acute and rapidly progressive neurologic syndrome developed in three of the four participants starting on the fifth day of drug administration. The main clinical features were headache, a cerebellar syndrome, memory impairment, and altered consciousness. Magnetic resonance imaging showed bilateral and symmetric cerebral lesions, including microhemorrhages and hyperintensities on fluid-attenuated inversion recovery and diffusion-weighted imaging sequences predominantly involving the pons and hippocampi. One patient became brain dead; the condition of two patients subsequently improved, but one patient had residual memory impairment, and the other patient had a residual cerebellar syndrome. One patient remained asymptomatic.ConclusionsAn unanticipated severe neurologic disorder occurred after ingestion of BIA 10-2474 at the highest dose level used in a phase 1 trial. The underlying mechanism of this toxic cerebral syndrome remains unknown.

Acute Postviral Encephalopathy: Pathologic and Radiologic Correlation in an Atypical Case.

The authors report a case of fatal acute encephalopathy following influenza infection, with slightly atypical pathological and imaging findings. A healthy 8-year-old boy with probable recent influenza A/B infection admitted for refractory seizures was placed on phenobarbital coma and later developed hemodynamic instability. Magnetic resonance imaging revealed bilateral cerebral and cerebellar white matter lesions and microhemorrhages. Following his demise, the autopsy revealed a large area of necrosis in the right centrum semiovale with similar lesions in the temporal and cerebellar regions. Microscopically, there was extensive coagulative necrosis, compatible with necrotizing white matter encephalopathy, and neuronal loss suggesting superimposed hypoxic–ischemia. The acute progressive neurologic deterioration was partly reminiscent on acute necrotizing encephalopathy, a condition recently associated with influenza A. In acute necrotizing encephalopathy, typical brain findings are characterized by bilateral thalamic necrosis/petechiae with variable white matter edema. The somewhat atypical findings in our case can relate to superadded cardiovascular collapse and hypoxic–ischemic effects.

Diffusion-weighted MRI for early diagnosis of neonatal herpes simplex encephalitis.

To determine the early changes and evolutions of brain diffusion-weighted imaging (DWI), and analyze prognostic factors of the early changes among patients with neonatal herpes simplex encephalitis (NHSE). We selected patients who developed encephalitis by 28 d after birth; had herpes simplex infection; and who underwent magnetic resonance imaging, including DWI, ⩽7 d of symptom onset. Thirty-two DWI scans between 0 and 28 d after onset in 13 patients and the clinical data were recruited. The distribution, evolution of the lesions, and neurological outcome were analyzed. DWI frequently showed multiple cortical lesions in both hemispheres in the early period and both hemispheres on DWI (8/9 scans at ⩽48 h, 7/7 patients). As time from onset increased, the cortical lesions tended to coincide with subcortical white matter lesions beneath the initial cortical lesions (p<0.01). Lesions from the cortex extended to the subcortical white matter in 7 patients. Deep cerebral lesions, involving basal ganglia, internal capsules, thalamus, were also found in 9 patients ⩽7 d of onset. The distributions of deep cerebral lesions (none/unilateral/bilateral) ⩽7 d of onset showed significant correlations with neurological prognoses (gross motor functions: p<0.01; developmental or intellectual quotient scores: p<0.01). Cortical lesions were main findings of DWI in NHSE in the early period. Bilateral deep cerebral lesions ⩽7 d were highly indicative of poor motor and cognitive outcomes.

Teaching Neuro Images : Conus medullaris involvement in cerebrospinal toxoplasmosis

A 41-year-old woman originally from West Africa presented with a 3-week history of generalized weakness. Clinical examination demonstrated quadriparesis, urinary incontinence, and reduced level of consciousness. The imaging of the neuraxis revealed multiple bilateral cerebral lesions, including basal ganglia and midbrain. Spinal cord imaging showed lesions in the conus medullaris (figure). The HIV test was reactive, with a CD4 count of 10 cells/µL (normal range 700–1,200/µL). CSF PCR for Toxoplasma gondii was positive. CSF cryptococcal antigen, fungal and mycobacterial cultures, Epstein-Barr virus PCR, and Mycobacterium tuberculosis PCR were negative.

Churg-Strauss syndrome mimicking myocardial infarction with cerebral vascular involvement

Churg-Strauss syndrome (CSS) is a rare multisystemic disorder defined by the American Rheumatological Society [1] as an eosinophilic vasculitis plus one or more of the following: asthmatic airway obstruction, [10 % eosinophils, migratory or transient pulmonary infiltrates, sinusitis and monoor poly-neuropathy. In a minority of cases the process involves the central nervous system [2] or the heart [3]. We describe a very rare case of a patient with simultaneous cardiac and encephalic involvement due to ChurgStrauss syndrome. A 59 y.o. male, whose medical history included mild hypertension, asthma, chronic sinusitis, and nasal polyposis, was admitted to the emergency department because of sudden onset of mental confusion. The neurological examination showed psychomotor slowing, mild right hemiparesis, bilateral Babinski sign, increased deep tendon reflexes in the four limbs, and instability in the standing position. An encephalic MRI showed multiple bilateral cerebral and cerebellar small ischemic lesions in diffusionweighted sequences (Fig. 1). Troponin I was markedly elevated (4.380 lg/l, with a further rapid increase to 8.140 lg/l), thus, the patient was transferred to the coronary unit. Coronarography did not show any stenosis (obviously, this could not rule out small vessel cardiac ischemia). A trans-thoracic echocardiogram and several EKGs were also normal, thus, the patient was transferred to our Stroke Unit because of the MRI lesions and of the mild right hemiparesis. Marked hyper-eosinophilia was found (absolute value 2.7 9 10/L, 24.3 % of total leukocytes), with a strong elevation of IgE (368 kU/L; normal range 0–25) and inflammation indexes. Parasites and bone marrow pathologic proliferation were ruled out. A total body CT scan showed pulmonary bilateral diffuse micro-nodular appearance with bilateral pleural effusions. Immunologic tests for vasculitis were normal with the exception of cANCA (positive 1:20). A tentative diagnosis of vasculitis (Churg-Strauss syndrome) was done, and methylprednisone 1 g daily i.v. was started. A dramatic improvement of

Heat stress presenting with encephalopathy and MRI findings of diffuse cerebral injury and hemorrhage

BackgroundHeat stress results in multiorgan failure and CNS injury. There a few case reports in the literature on the neurological consequences of heat stress.Case presentationWe describe a patient with heat stress presenting with encephalopathy and bilateral cerebral, cerebellar, and thalamic lesions and intraventricular hemorrhage on MRI.ConclusionHeat stress should be in the differential diagnosis of patients presenting with encephalopathy and elevated serum inflammatory markers especially if the history suggests a preceding episode of hyperthermia.

Asymmetrical Contribution of Brain Structures to Treatment-Resistant Depression As Illustrated by Effects of Right Subgenual Cingulum Stimulation

Major depressive disorder is one of the most common psychiatric disorders, with a worldwide lifetime prevalence rate of 10%-20% in women and a slightly lower rate in men. While many patients are successfully treated using established therapeutic strategies, a significant percentage of patients fail to respond. This report describes the successful recovery of a previously treatment-resistant patient following right unilateral deep brain stimulation of Brodmann's area 25. Current therapeutic approaches to treatment-resistant patients are reviewed in the context of this case with an emphasis on the role of the right and left hemispheres in mediating disease pathogenesis and clinical recovery.

Constructional ability in two- versus three-dimensions: Relationship to spatial vision and locus of cerebrovascular lesion

Introduction Clinical evaluation and research on constructional ability have come to rely almost exclusively on two-dimensional tasks such as graphomotor copying or mosaic Block Design (BD). A return to the inclusion of a third dimension in constructional tests may increase the spatial demands of the task, and improve understanding of the relationship between visual perception and constructional ability in patients with cerebral disease. Method Subjects were patients ( n = 43) with focal or multifocal cerebrovascular lesions as determined by CT or MRI. Tests of temporal orientation, verbal intelligence, language, object vision and spatial vision were used to determine which factors were predictive of performance on two-dimensional BD and Three-Dimensional Block Construction (3-DBC) tasks. Results Stepwise linear regression indicated that spatial vision predicted BD performance, and was even more strongly predictive of 3-DBC. Other cognitive domains did not account for significant additional variance in performance of either BD or 3-DBC. Bilateral cerebral lesions produced more severe deficits on BD than did unilateral cerebral lesions. The presence of a posterior cerebral lesion was the significant factor in producing deficits in 3-DBC. Conclusions The spatial aspect of a constructional task is enhanced when the patient is required to assemble an object in all three dimensions of space. In the typical patient with cerebrovascular disease, constructional deficits typically occur in the context of a wider syndrome of deficits in spatial vision.

Leukoencephalopathy with intracranial calcifications and cysts in an adult: Case report and review of literature

Leukoencephalopathy, intracranial calcifications, and cysts (LCC) is a very rare cerebral disorder, first described in 3 children in 1996. It has subsequently been reported in adults and children from Europe and America, but has not so far been reported from Asia. We report an adult patient with pathologically proven LCC from a tertiary care hospital in South India. He presented with features of ataxia and raised intracranial pressure. Magnetic resonance imaging of the brain showed multiple bilateral cerebral cystic lesions along with diffuse white matter lesions in the cerebral and cerebellar white matter, and computed tomography of brain showed multiple calcifications in the white matter and basal ganglia. A large right cerebellar cyst causing mass effect was surgically excised. Histopathologic features were consistent with earlier reports of LCC and showed Rosenthal fibers, angiomatous changes, and calcifications. Our report suggests that although it is rare, LCC has a global distribution.

Reversible Hypertensive Encephalopathy in Childhood

Reversible hypertensive encephalopathy (RHE) is clinically characterized by sudden onset of headache, visual changes, altered mental functioning and seizures. Typical MRI features include bilateral cerebral lesions depicted as hyperintense in T2 sequences and iso or hypointense in T1 images. These areas of vasogenic oedema are best visualized by diffusion-weighted imaging (DWI) sequences and apparent diffusion coefficient (ADC) maps. The neuroradiological changes usually resolve completely at follow-up. The pathogenesis of RHE is poorly understood. A number of factors have been implicated including an elevated systemic blood pressure breaking through the autoregulation capacity of the cerebral vascular system, but also immunosuppressant medication like ciclosporine A and tacrolimus as well as interferon alfa. A retrospective study of the five-year period 1999–2004 was undertaken on patients admitted to our Institution with clinical and neuroradiological features compatible with a diagnosis of RHE. Neuroradiological investigation disclosed hypodense areas on CT scan in four out of five cases and hyperintense images in T2 and FLAIR MRI sequences in eight out of eight patients, mainly affecting the unilateral or bilateral occipitoparietal regions. Clinical symptoms and MRI findings had normalized at follow-up in five cases between 2 and 11 weeks, whereas three patients died from complications of the underlying disease. RHE is not an uncommon complication arising in childhood cancer. MRI with DWI sequences is the gold standard for the detection and differential diagnosis of RHE-induced changes allowing adequate treatment and follow-up monitoring.

Impaired trophic interactions between the cerebellum and the cerebrum among preterm infants.

Advanced neuroimaging techniques have brought increasing recognition of cerebellar injury among premature infants. The developmental relationship between early brain injury and effects on the cerebrum and cerebellum remains unclear. To examine whether cerebral parenchymal brain lesions among preterm infants are associated with subsequent decreases in cerebellar volume and, conversely, whether primary cerebellar injury is associated with decreased cerebral brain volumes, with advanced, 3-dimensional, volumetric MRI at term gestational age equivalent. Total cerebellar volumes and cerebellar gray and myelinated white matter volumes were determined through manual outlining for 74 preterm infants with unilateral periventricular hemorrhagic infarction (14 infants), bilateral diffuse periventricular leukomalacia (20 infants), cerebellar hemorrhage (10 infants), or normal term gestational age equivalent MRI findings (30 infants). Total brain and right/left cerebral and cerebellar hemispheric volumes were calculated. Unilateral cerebral brain injury was associated with significantly decreased volume of the contralateral cerebellar hemisphere. Conversely, unilateral primary cerebellar injury was associated with a contralateral decrease in supratentorial brain volume. Cerebellar gray matter and myelinated white matter volumes were reduced significantly not only among preterm infants with primary cerebellar hemorrhage but also among infants with cerebral parenchymal brain injury. These data suggest strongly that both reduction in contralateral cerebellar volume with unilateral cerebral parenchymal injury and reduction in total cerebellar volume with bilateral cerebral lesions are related to trophic transsynaptic effects. Early-life cerebellar injury may contribute importantly to the high rates of cognitive, behavioral, and motor deficits reported for premature infants.

Constructional apraxia in patients with closed head injury

Constructional apraxia is a disorder characterized by an inability to join the elements into a unity. It has not been studied much in patients with closed head injury (CHI). Forty-one patients with CHI were examined, of which 11 (26.83%) were with the right-sided, 12 (29.27%) with the left-sided, and 18 (43.90%) with bilateral lesion using the Wechsler Individual Intelligence Test (VITI) - Serbian version, Rey Complex Figure (RCF) test, Trail Making Test - TMT A and B, and the Wisconsin Card Sorting Test (WCST). Intelligence quotient (IQ) was significantly higher in the patients with the right-sided (95.27) and bilateral cerebral lesions (87.56) than in the left-sided (84.42). RCF scores did not show any significant difference regarding the side of the lesion, but was numerically the lowest scores were in patients with bilateral brain damage. Patients with left-sided lesions had the score of 30.63, right-sided of 28.68, and bilateral of 27.39. TMT B showed a significantly lower result in patients with the left-sided (196.50 seconds) and bilateral lesions (192.07 seconds) compared to the right-sided (140.14 seconds). WCST scores were not significantly different regarding the side of the lesion, but the absolute value of the categories was less than expected. Constructional apraxia was more frequently present in the patients with CHI than it was previously considered. The use of sensitive tests can show the presence of the disorder mainly in bilateral, but also in unilateral lesions.

Thrombose sévère révélant un syndrome des antiphospholipides chez 2 jeunes filles atteintes d’un lupus érythémateux systémique

We report two pediatric patients with unusual, aggressive initial manifestation of antiphospholipid antibody syndrome secondary to systemic lupus erythematosus. The first patient, a 13-year-old girl, presented with bilateral amaurosis and ischemic cerebral lesions. The second, another 13-year-old girl, presented with cerebral venous sinus thrombosis and membranous glomerulonephritis. Both patients improved after treatment with anticoagulants and immunosuppressive drugs, two therapies that are aimed at modulating the immune response or towards preventing thromboembolic events. However, there is no consensus regarding the duration and intensity of oral anticoagulation in children with antiphospholipid antibody syndrome.

Unusual and aggressive thrombotic onset in two children with antiphospholipid-antibody syndrome and systemic lupus erythematosus

We report two pediatric patients with unusual, aggressive initial manifestation of antiphospholipid antibody syndrome secondary to systemic lupus erythematosus. The first patient, a 13-year-old girl, presented with bilateral amaurosis and ischemic cerebral lesions. The second, another 13-year-old girl, presented with cerebral venous sinus thrombosis and membranous glomerulonephritis. Both patients improve after treatment with anticoagulants and immunosuppressive drugs, two therapies that are aimed at modulating the immune response or towards preventing thromboembolic events. However, there is no consensus regarding the duration and intensity of oral anticoagulation in children with antiphospholipid antibody syndrome.

Formant Interaction as a Cue to Vowel Perception: A Case Report

Accumulating evidence indicates that cerebral processing of consonants and vowels is separable. It has been shown that disordered temporal acuity leads to disturbed consonant perception in cases with pure word deafness. In contrast, there has been no clear explanation of how vowel perception is impaired. We examined a patient with auditory agnosia, who showed a differential ability to identify the five Japanese vowels after bilateral cerebral lesions. He correctly identified the vowel [a] in more than 70% of auditory presentations, whereas he identified [i] in only about 30% of presentations. The difference between the first and second formant frequencies “F2–F1” and an artificially defined value “F1–(F2–F1)” for each vowel correlated significantly with the percentage of correct identifications. These findings support the hypothesis that vowel perception is based on formant interactions.