Functional brain networks in Developmental Topographical Disorientation.

Despite a decade-long study on Developmental Topographical Disorientation, the underlying mechanism behind this neurological condition remains unknown. This lifelong selective inability in orientation, which causes these individuals to get lost even in familiar surroundings, is present in the absence of any other neurological disorder or acquired brain damage. Herein, we report an analysis of the functional brain network of individuals with Developmental Topographical Disorientation ($n = 19$) compared against that of healthy controls ($n = 21$), all of whom underwent resting-state functional magnetic resonance imaging, to identify if and how their underlying functional brain network is altered. While the established resting-state networks (RSNs) are confirmed in both groups, there is, on average, a greater connectivity and connectivity strength, in addition to increased global and local efficiency in the overall functional network of the Developmental Topographical Disorientation group. In particular, there is an enhanced connectivity between some RSNs facilitated through indirect functional paths. We identify a handful of nodes that encode part of these differences. Overall, our findings provide strong evidence that the brain networks of individuals suffering from Developmental Topographical Disorientation are modified by compensatory mechanisms, which might open the door for new diagnostic tools.

A neural circuit for spatial orientation derived from brain lesions.

There is disagreement regarding the major components of the brain network supporting spatial cognition. To address this issue, we applied a lesion mapping approach to the clinical phenomenon of topographical disorientation. Topographical disorientation is the inability to maintain accurate knowledge about the physical environment and use it for navigation. A review of published topographical disorientation cases identified 65 different lesion sites. Our lesion mapping analysis yielded a topographical disorientation brain map encompassing the classic regions of the navigation network: medial parietal, medial temporal, and temporo-parietal cortices. We also identified a ventromedial region of the prefrontal cortex, which has been absent from prior descriptions of this network. Moreover, we revealed that the regions mapped are correlated with the Default Mode Network sub-network C. Taken together, this study provides causal evidence for the distribution of the spatial cognitive system, demarking the major components and identifying novel regions.

Anatomical and functional predictors of disorientation after first-ever brain damage.

BACKGROUND AND OBJECTIVES: Disorientation is a frequent consequence of acute brain injury or diffuse disorders, such as confusional states or dementia. Its anatomical correlates are debated. Impaired memory as its commonly assumed mechanism predicts that disorientation is associated with medial temporal damage. The alternative is that disorientation reflects defective orbitofrontal reality filtering (ORFi) - a specific failure to identify whether thoughts or memories refer to present reality or not. The latter is a function of the posterior orbitofrontal cortex and connected structures. This study examined the mechanisms and anatomical basis of disorientation in an unselected group of patients with first-ever subacute brain injury. METHODS: Participants hospitalized for neurorehabilitation were asked to participate in this observational cohort study if they had first-ever organic hemispheric brain dysfunction as evident in a localizable brain lesion or verbal amnesia (often without localizable brain damage). Orientation to time, place, situation and person was tested with a 20-items questionnaire. To identify the mechanisms of disorientation, we determined its correlations with executive tasks, verbal episodic memory, and ORFi in all patients. ORFi was examined with a continuous recognition task, which measures learning and item recognition in the first run, and ORFi as reflected in the increase of false positive responses in the second run (temporal context confusion). Lesions of patients having localizable brain damage were manually delineated and normalized before entering multivariate lesion-symptom-mapping (LSM) to determine anatomical predictors of orientation. RESULTS: Eighty-four patients (61.1 ± 14.4 years, 29 women) were included. Among measures of memory and executive functioning, a step-wise regression retained temporal context confusion (R = -0.71, p < 0.0001), item recognition (R = 0.67, p < 0.0001) and delayed free recall (R = 0.63, p < 0.0001) as significant predictors of orientation. LSM was possible in 67 participants; it revealed an association of disorientation with damage of the right OFC and the bilateral head of the caudate nucleus. CONCLUSION: Disorientation in non-confused, non-demented patients with first-ever brain damage is associated with impaired orbitofrontal reality filtering and memory dysfunction, but not with executive dysfunction. Its main anatomical determinant is damage to the orbitofrontal cortex and its subcortical relay, the head of the caudate.

Non-convulsive status epilepticus possibly induced by a rapid correction of severe hyperkalemia: a case report and literature review.

BACKGROUND: Patients with chronic kidney disease frequently develop neurological complications including confusion and altered consciousness. Non-convulsive status epilepticus, which is characterized by a change in behavior and/or mental process accompanied by epileptiform discharges on electroencephalogram in the absence of convulsive seizures, is one of the overlooked causes of altered consciousness. The incidence and precise pathophysiological mechanism of non-convulsive status epilepticus in patients with kidney disease, and especially in patients with electrolyte disturbances, remains unknown. We recently treated an older patient with chronic kidney disease and severe hyperkalemia in whom non-convulsive status epilepticus developed following a correction of severe hyperkalemia. CASE PRESENTATION: An 82-year-old male was admitted to our hospital at midnight because of weakness of all four limbs (Day 1). He underwent urgent hemodialysis for severe hyperkalemia (9.84 mEq/L) and his serum potassium concentration decreased to 4.97 mEq/L. He regained full consciousness and his limb weakness improved on the morning of Day 2, but he became confused in the evening. Electroencephalogram revealed repeated low-voltage ictal discharges in the right occipital region and a diagnosis of non-convulsive status epilepticus was made. Following medication with fosphenytoin and phenytoin, the patient became fully alert and orientated on Day 8. CONCLUSION: We speculate that a rapid correction of hyperkalemia was the possible cause of non-convulsive status epilepticus development. To our knowledge, this is the first report of non-convulsive status epilepticus from a potassium abnormality. We described a case of this condition in detail and summarized 78 previous case reports of non-convulsive status epilepticus with kidney disease or electrolyte disturbances.

Acute confusional state in HaNDL syndrome.

OBJECTIVE: To assess epidemiological, clinical and neuroimaging features of acute confusional state in the Headache and Neurological Deficits with cerebrospinal fluid Lymphocytosis (HaNDL) syndrome. BACKGROUND: HaNDL is an increasingly recognized syndrome in which migraine-like headache episodes accompanied by hemiparaesthesia and/or hemiparesis and/or dysphasia are associated to CSF lymphocytic pleocytosis. The International Classification of Headache Disorders (ICHD-3) includes HaNDL syndrome in group 7 "headache attributed to non-vascular intracranial disorder" code 7.3.5, and lists the HaNDL-associated signs/symptoms that may be found less frequently. Confusional state is not mentioned in the 7.3.5-ICHD-3 "notes" or "comments" section as part of the HaNDL neurological spectrum. Moreover, the acute confusional state pathogenesis in HaNDL syndrome remains still uncertain and debated. METHODS: Here, we report a 32-year-old male who complained episodes of migraine-like headache and left hemiparaesthesia complicated by confusional state which led to discovering CSF lymphocytosis. Since other workup to determine the cause of his symptoms was otherwise negative, he was diagnosed as having HaNDL syndrome. We also ascertained and reviewed all available reports of HaNDL to assess the significance of confusional state in this syndrome. RESULTS: The search yielded 159 HaNDL cases among single reports and small/large series. Out of 159 patients who fulfilled the inclusion criteria for HaNDL according to the current ICHD at the time of diagnosis, 41 (25.7%) presented with acute confusional state. Among 41 HaNDL patients with confusional state, 16 (66.6%) out of 24 who underwent spinal tap had increased opening pressure. CONCLUSION: We propose that a mention of acute confusional state may be included in the "comments" section of "7.3.5-syndrome of transient headache and neurological deficits with cerebrospinal fluid lymphocytosis (HaNDL)," when ICHD-3 diagnostic criteria will be updated. Moreover, we speculate that intracranial hypertension may play a role in the pathogenesis of the acute confusional state associated to HaNDL syndrome. Larger case series are needed to evaluate this hypothesis.

[Recognizing acute confusional syndrome and neurocognitive disorders in the emergency department]. / Reconnaître un syndrome confusionnel aigu et des troubles neurocognitifs aux urgences.

In the heart of the emergency room, when the nurse takes charge of the patient, he/she must be able to distinguish between an acute confusional syndrome and psychobehavioral symptoms related to neurocognitive disorders. Indeed, early identification of the confusional syndrome is essential to accelerate the implementation of non-drug measures by the nurse in order to reduce its duration and the induced complications.

Severe developmental topographical disorientation associated with ADHD and dyscalculia: A case report.

We report the clinical case of AB, a right-handed 19-year-old woman who presents severe developmental topographical disorientation, a relatively rare syndrome, leading to difficulties in navigating in familiar (and novel) environments. This symptomatology appears without acquired cerebral damage (MRI described as normal) nor more global cognitive disability (high degree of education achieved). An extensive assessment of spatial cognition with different aspects of underlying cognitive processes is first presented. Second, the patient's preserved cognitive abilities and her major difficulties in calculation, as well as her attention deficit, as seen in a detailed neuropsychological assessment, are reported. For the first time to our knowledge, we show that developmental topographical disorientation can be associated with other developmental cognitive disorders affecting number processing (dyscalculia) and attention (Attention Deficit-Hyperactivity Disorder (ADHD)). We discuss the links between these different cognitive processes in relation to visuo-spatial working memory and magnitude representation, which could represent common denominators for all these syndromes. This case report highlights the importance of thoroughly assessing potentially associated neurocognitive disorders in developmental topographical disorientation. In addition, it highlights the necessity to keep in mind the prevalence of spatial difficulties in the assessment of children and adolescents with other neurodevelopmental syndromes. Finally, this case study raises a new question about the nosology of developmental disorders affecting the visuo-spatial and spatial domains.

A man in his forties with acute confusion. / En mann i 40-årene med akutt forvirring.

Rapid and thorough assessment of acute neuropsychiatric symptoms is essential for effective treatment. Here we describe a patient with a distinctive but relatively rare disease.