Frequency, clinical presentation and outcome of vigilance impairment in patients with uni- and bilateral ischemic infarction of the paramedian thalamus

Journal of Neurology https://doi.org/10.1007/s00415-021-10565-y ORIGINAL COMMUNICATION Frequency, clinical presentation and outcome of vigilance impairment in patients with uni‑ and bilateral ischemic infarction of the paramedian thalamus Merve Fritsch1,3 · Kersten Villringer2 · Ramanan Ganeshan1,2 · Ida Rangus1,2 · Christian H. Nolte1,2 Received: 25 November 2020 / Revised: 13 April 2021 / Accepted: 15 April 2021 © The Author(s) 2021 Abstract Ischemic stroke of the paramedian thalamus is a rare differential diagnosis in sudden altered vigilance states. While efforts to describe clinical symptomatology exist, data on the frequency of paramedian thalamic stroke as a cause of sudden impaired vigilance and on accompanying clinical signs and outcome are scarce. We retrospectively analyzed consecutive patients admitted to a tertiary stroke center between 2010 and 2019 diagnosed with paramedian thalamic stroke. We evaluated frequency of vigilance impairment (VI) due to paramedian thalamic stroke, accompanying clinical signs and short-term outcome in uni- versus bilateral paramedian lesion location. Of 3896 ischemic stroke patients, 53 showed a paramedian thalamic stroke location (1.4%). VI was seen in 29/53 patients with paramedian thalamic stroke and in 414/3896 with any stroke (10.6%). Paramedian thalamic stroke was identified as causal to VI in 3.4% of all patients with initial VI in the emergency department and in 0.7% of all ischemic stroke patients treated in our center. Accompanying clinical signs were detected in 21 of these 29 patients (72.4%) and facilitated a timely diagnosis. VI was significantly more common after bilateral than unilateral lesions (92.0% vs. 21.4%; p < 0.001). Patients with bilateral paramedian lesions were more severely affected, had longer hospital stays and more frequently required in-patient rehabilitation. Paramedian thalamic lesions account for about 1 in 15 stroke patients presenting with impaired vigilance. Bilateral paramedian lesion location is associated with worse stroke severity and shortterm outcome. Paying attention to accompanying clinical signs is of importance as they may facilitate a timely diagnosis. Keywords Vigilance impairment · Ischemic stroke · Paramedian thalamus · Outcome Introduction * Merve Fritsch 1 Department of Neurology, Charité Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin and Berlin Institute of Health, Charitéplatz 1, 10117 Berlin, Germany 2 Center for Stroke Research Berlin, Charité Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin and Berlin Institute of Health, Berlin, Germany 3 Department of Psychiatry and Psychotherapy, CCM, Charité-Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin and Berlin Institute of Health, Berlin, Germany Sudden impaired vigilance is a common diagnostic challenge due to numerous differential diagnoses. Seldom, it may be caused by ischemic stroke in the paramedian thalamus [1]. The paramedian thalamus is typically supplied by the paramedian artery (also called mesencephalic artery), arising from the P1-segment of the posterior cerebral artery (PCA). The occlusion of the “Artery of Percheron”, an anatomical variation whereby both paramedian arteries arise from a common P1, often leads to bilateral paramedian thalamic infarction [2]. Paramedian lesions account for 25% of all thalamic but only for 0.6% of all ischemic strokes, indicating it to be a rare stroke lesion location [3]. Their seldom occurrence and heterogeneity of clinical presentation might lead to a delay or even misclassification of diagnosis [4]. Since paramedian lesions have been described to result in vigilance impairment to the extent of comatose states, knowledge on frequency, clinical presentation and of 13 Vol.:(0123456789) Journal of Neurology prognosis may help to facilitate timely diagnoses and guide further therapeutic measures [5]. In addition to vigilance impairment, clinical presentation may include gaze palsy and sensorimotor symptoms. Identification of these may help the clinician to the correct diagnosis [6]. However, data on frequency of paramedian thalamic stroke as cause of vigilance impairment, frequency of accompanying clinical signs and outcome of uni- and bilateral paramedian thalamic lesions are scarce. Aim We investigated the frequency, clinical presentation and short-term outcome of ischemic paramedian thalamic lesions in a large cohort of ischemic stroke patients to further understand the role of the paramedian thalamus in sudden vigilance impairment. We additionally analyzed what factors might influence facilitation of a timely diagnosis. Methods The data that support the findings of this study are available from the corresponding author upon reasonable request. Participants We conducted a retrospective analysis of consecutive stroke patients who were admitted to the Stroke Unit or Intensive Care Unit of the Charité Campus Benjamin Franklin in Berlin between 2011 and 2019. We screened for the frequency of vigilance impairment as a presenting symptom and for the frequency of thalamic strokes. We then analyzed the lesion location in patients that had received an MRI showing a lesion confined to the thalamus. For lesion analysis, patients were categorized into uni- and bilateral paramedian thalamic lesions. In addition, we calculated the rate of uni- and bilateral paramedian thalamic lesions among all neurologic cases presenting with “sudden vigilance impairment” of unknown cause admitted to our emergency department (ED) during the observation period. The latter diagnosis was given after exclusion of obvious causes such as metabolic (e.g., hypoglycemia) or circulatory disease (e.g., syncope), intracranial disease (e.g., intracranial bleeding, large hemispheric ischemic stroke, large vessel occlusion), infectious disease and seizures. Assessment of vigilance and prognosis Patients’ vigilance states were assessed by board-certified physicians according to item 1A of the National Institutes 13 of Health Stroke Scale (NIHSS; Level of consciousness, 0–3 points) which corresponds to the “eye opening” part of the Glasgow Coma Scale (GCS) [7, 8]. Patients received standardized vigilance testing at least every 6 h for the duration of their stay on the stroke unit (minimum of 24 h). If patients scored 1 or more points on this item, vigilance impairment was assumed. The number of days in which patients showed vigilance impairment and the number of days under stroke unit supervision were analyzed (as in 24-h units). Outcome was assessed by comparing patients’ stroke severity (NIHSS) and degree of independence (mRS) upon admission and discharge, their need for in- or outpatient rehabilitation as well as in-hospital death as a consequence of stroke. In addition, the impact of paramedian stroke location on outcome was in (...truncated)