Transient topographical disorientation due to right‐sided hippocampal hemorrhage

Abstract

IntroductionTopographical disorientation is defined as the inability to recognize familiar or unfamiliar environments. While its slowly progressive development is a common feature of neurodegenerative processes like Alzheimer's dementia, acute presentations are less frequent and mostly caused by strategic lesions within the cerebral navigation network. Depending on the lesion site, topographical disorientation can originate from deficits in landmark recognition and utilization for route planning (egocentric navigation deficit), or disturbance of an overarching cognitive map of the spatial environment (allocentric navigation deficit). However, objective measurements of spatial navigation performance over time are largely missing in patients with topographical disorientation.MethodsWe here report a 55‐year‐old patient with acute topographical disorientation as the single symptom of right‐sided hippocampal hemorrhage and present quantitative gaze‐monitoring head camera‐based analyses of his path‐finding strategy and visual exploration behavior in a real space navigation paradigm.ResultsThe patient exhibited severe allocentric and also egocentric navigation deficits during the acute phase, shown by higher error rates at finding target items. In addition, he showed a more extensive use of search saccades toward, and fixations on, landmarks that could potentially serve as spatial cues. These deficits had been completely compensated for after four months, when the patient performed unremarkably in the real space navigation task, and used even more strongly allocentric path optimization strategies than age‐matched controls.ConclusionsThis case report highlights the integral function and right‐sided dominance of the hippocampal formation in the cerebral navigation network in humans. It shows that the cognitive map can be restored completely despite a residual hippocampal lesion, which illustrates the enormous plasticity of the cerebral navigation network in humans.

The neural correlates of topographical disorientation—a lesion analysis study

“…The right PHG has been repeatedly linked to topographical disorientation 14,15 . It has been suggested that the PHG plays an important role in egocentric and allocentric orientation.…”

“…The right PHG has been repeatedly linked to topographical disorientation. 14 , 15 It has been suggested that the PHG plays an important role in egocentric and allocentric orientation. For example, patients with right‐sided posterior PHG lesions are impaired on a task involving allocentric orientation, for example, a virtual maze acquisition task.…”

Functional neuroanatomy of the vestibular cortex and vestibular stimulation methods for neuroimaging studies

“…Vestibular symptoms such as dizziness are among the most common symptoms accompanying transient global amnesia and transient topographical disorientation due to hippocampal lesions. 41,42 CalORIC vesTIbUlaR sTImUlaTION CVS as developed by the otologist Robert Bárány revolutionized clinical vestibular research. 43 This has recently become a popular research tool again, especially for studying the vestibular cortex.…”

A bedside application-based assessment of spatial orientation and memory: approaches and lessons learned

“…These tests cannot distinguish between deficits due to general cognitive and memory impairments, and specific deficits from sensorimotor degradation that then impact the establishment of the mental models or cognitive maps necessary for orientation in space. Clinical tests involving navigation in real environments have detected differential navigational deficits in allocentric and egocentric space [6]. However, these tests are not widely available and we just beginning to understand the systematic read-out parameters that can be extracted in real navigation paradigms [7].…”