Abstract
BackgroundMacrosomatognosiais the illusory sensation of a substantially enlarged body part. This disorder of the body schema, also called “Alice in wonderland syndrome” is still poorly understood and requires careful documentation and analysis of cases. The patient presented here is unique owing to his unusual macrosomatognosia phenomenology, but also given the unreported localization of his most significant lesion in the right thalamus that allowed consistent anatomo-clinical analysis.Case presentationThis 45-years old man presented mainly with long-lasting and quasi-delusional macrosomatognosia associated to sensory deficits, both involving the left upper-body, in the context of a right thalamic ischemic lesion most presumably located in the ventral posterolateral nucleus. Fine-grained probabilistic and deterministic tractography revealed the most eloquent targets of the lesion projections to be the ipsilateral precuneus, superior parietal lobule,but also the right primary somatosensory cortex and, to a lesser extent, the right primary motor cortex. Under stationary neurorehabilitation, the patient slowly improved his symptoms and could be discharged back home and, later on, partially return to work.ConclusionWe discuss deficient neural processing and integration of sensory inputs within the right ventral posterolateral nucleus lesion as possible mechanisms underlying macrosomatognosia in light of observed anatomo-clinical correlations. On the other hand, difficulty to classify this unique constellation of Alice in wonderland syndrome calls for an alternative taxonomy of cognitive and psychic aspects of illusory body-size perceptions.
Highlights
Macrosomatognosiais the illusory sensation of a substantially enlarged body part
We discuss deficient neural processing and integration of sensory inputs within the right ventral posterolateral nucleus lesion as possible mechanisms underlying macrosomatognosia in light of observed anatomoclinical correlations. Difficulty to classify this unique constellation of Alice in wonderland syndrome calls for an alternative taxonomy of cognitive and psychic aspects of illusory body-size perceptions
Compared to the contralateral side, deterministic tractography showed a profound reduction of right thalamic fiber tracts targeting the precuneus (~ 80% reduction, Figs. 3a), the ipsilateral superior parietal lobule (SPL, ~ 90% reduction, Figs. 3b) and, to some extent, in fibers pointing to the primary somatosensory cortex (S1, ~ 60% reduction, not shown)
Summary
We report the case of a patient presenting mainly with long-lasting left-sided MSG and sensory deficits presumably associated with a right thalamic stroke lesion restricted to the VPL, that progressively improved over months. Detailed description of the patient’s initial neurological complains, including a precise time when the main symptoms discussed in the paper started, lacked. Our findings have to be considered with caution, especially when generalizing derived conclusions. This first detailed analysis of MSG in the context of a non-cortical brain lesion explores interesting hypotheses that would highly contribute, if confirmed, to understand mechanisms underlying this unusual symptom, as well as the role of the VPL
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