Thalamic Aphasia: a Review

Purpose of Review Thalamic aphasia is a rare language disorder resulting from lesions to the thalamus. While most patients exhibit mild symptoms with a predominance of lexical-semantic difficulties, variations in phenotype have been described. Overall, the exact mechanisms of thalamic aphasia await empirical research. The article reviews recent findings regarding phenotypes and possible underlying mechanisms of thalamic aphasia. Recent Findings Variations in phenotype of thalamic aphasia may be related to different lesion locations. Overall, the thalamus' role in language is thought to be due to its involvement in cortico-thalamic language networks with lesioning of certain nuclei resulting in the diachisis of otherwise interconnected areas. Its possible monitoring function in such a network might be due to its different cellular firing modes. However, no specific evidence has been collected to date. While recent findings show a more distinct understanding of thalamic aphasia phenotypes and possible underlying mechanisms, further research is needed. Additionally, as standard language testing might oftentimes not pick up on its subtle symptoms, thalamic aphasia might be underdiagnosed

Frequency and phenotype of thalamic aphasia

Background: Aphasia is a recognized presenting symptom of thalamic lesions. Little is known regarding its frequency and phenotype. We examined the frequency of thalamic aphasia following Isolated Acute unilateral ischemic Lesions in the Thalamus (IALT) with respect to lesion location. Furthermore, we characterized thalamic aphasia according to affected language domains and severity. Methods: Fifty-two patients with IALT were analyzed [44% female, median age: 73 years (IQR: 60-79)]. Lesion location was determined using 3-Tesla magnetic resonance imaging and categorized as anterior, posterior, paramedian or inferolateral. Standardized language assessment was performed using the validated Aphasia checklist (ACL) directly after symptom onset. Aphasia was defined as an ACL sum score of < 135 (range: 0-148). Results: Of 52 patients, 23 (44%) fulfilled the ACL diagnostic criteria for aphasia, including nearly all lesion locations and both sides. The average ACL sum score was 132 +/- 11 (range: 98-147). Aphasia was characterized by deficits within domains of complex understanding of speech and verbal fluency. Patients with left anterior IALT were most severely affected, having significantly lower ACL scores than all other patients (117 +/- 13 vs. 135 +/- 8; p < 0.001). In particular, aphasia in patients with left anterior IALT was characterized by significantly worse performance in the rating of verbal communication, verbal fluency, and naming (all p <= 0.001). Conclusion: Aphasia occurs in almost half of patients with focal thalamic lesions. Thalamic aphasia is not confined to one predefined thalamic lesion location, but language deficits are particularly pronounced in patients with left anterior IALT presenting with a distinct pattern

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

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 short-term outcome. Paying attention to accompanying clinical signs is of importance as they may facilitate a timely diagnosis

The role of leptin in improved learning performance in adipose patients following bariatric surgery

Einleitung: Adipositas wird in Verbindung mit einer schlechteren kognitiven Leistungsfähigkeit und einem erhöhten Risiko für die Entwicklung einer Alzheimer Demenz gebracht. Die vorliegende Arbeit befasst sich primär mit der Frage, ob bariatrische Chirurgie bei adipösen Personen zu einer besseren Lernleistung führt. Der Leptinplasmaspiegel ist bei Adipositas chronisch erhöht, was vermutlich zu einer zentralen Leptinresistenz führt und in einer eingeschränkten neuroprotektiven Wirkung des Leptins im Gehirn resultiert. Es wurde daher untersucht, ob ein erhöhter Leptinserumspiegel mit einer schlechteren Lernleistung assoziiert ist und ob es einen Zusammenhang zwischen möglicher Verbesserung der Lernleistung und Veränderung des Leptinspiegels infolge der Intervention gibt. Methodik: 26 adipöse Probanden wurden in die Interventionsgruppe (IG) und 27 in die Kontrollgruppe (KG) eingeschlossen. Zur Follow-up-Untersuchung nach 6 Monaten konnten noch 20 Interventionsprobanden und 17 Kontrollprobanden erfasst werden. Der jeweilige Untersuchungstermin bestand aus einer medizinischen Untersuchung und einer neuropsychologischen Testung. Unterschiede der Testergebnisse zwischen den Gruppen bei der Follow- up-Untersuchung wurden mittels ANCOVAs mit den Kovariaten „Alter“ und „Baseline-Testergebnis“ untersucht. Zusammenhänge zwischen den neurokognitiven Testleistungen und dem Leptinspiegel wurden anhand von partiellen Korrelationen mit der Kontrollvariable „Alter“ untersucht. Ergebnisse: 6 Monate postoperativ zeigte die IG im Vergleich zur KG keine signifikante Verbesserung der Lernleistung, lediglich innerhalb der IG verbesserte sich die Lernleistung signifikant im Vergleich zur Baseline-Untersuchung (p = ,016). Die IG zeigte bei der Follow-up-Untersuchung im Vergleich zur KG jedoch signifikante Verbesserung der Exekutivfunktionen (Interferenzleistung; p = ,032). Bei der Baseline-Untersuchung wurde ein signifikant negativer Zusammenhang zwischen dem Leptinspiegel und der Lernleistung beobachtet (r = -,411, p = ,009). Bei der Follow-up-Untersuchung wurde ein positiver Zusammenhang zwischen der Verbesserung in der Interferenzleistung und der Verringerung des Leptinspiegels verzeichnet (r = ,705, p = ,001). Im Rahmen der explorativen Untergruppenanalyse nach OP-Verfahren zeigte sich, dass der Roux-en-Y-Magenbypass (n = 7) im Vergleich zur Vertikale-Sleeve-Gastrektomie (n = 12) zu einer signifikant höheren Gewichtsabnahme führt, die mit einer Verbesserung von Exekutivfunktionen, Lernen und Gedächtnis einherging. Schlussfolgerungen: Es konnte keine Verbesserung der Lernleistung infolge von bariatrischer Chirurgie verzeichnet werden, jedoch zeigte sich eine Verbesserung der exekutiven Funktionen. Die vorliegenden Ergebnisse sollten nun in größeren Studien überprüft werden, dabei könnten insbesondere Studien mit Beobachtungszeiträumen über Jahrzehnte klären, ob bariatrische Chirurgie zur Senkung des Demenz-Risikos beiträgt. Der Einfluss des Leptins auf die Lernleistung konnte nicht abschließend geklärt werden. Möglicherweise persistierte die Leptinresistenz noch zum Zeitpunkt der Follow-up- Untersuchung, so dass Leptin seine neuroprotektive Funktionen nur eingeschränkt ausüben konnte. Daher wären genauere Untersuchungen von molekularen Mechanismen der Leptinresistenz und deren Reversibilität vonnöten.Introduction: There is evidence that obesity leads to cognitive dysfunction and increases the risk of developing Alzheimer’s disease. The following thesis investigates whether learning improves following bariatric surgery. Obesity is associated with high serum leptin levels which supposedly leads to a central leptin resistance and the inability of leptin to exhibit neuroprotective effects in the brain. Thus, it was examined whether elevated leptin levels result in a worse learning ability. Furthermore, it was analyzed whether the supposed improvement of learning ability is related to a decrease of leptin levels following bariatric surgery. Methods: 26 obese individuals were included in the intervention group and 27 in the control group. At 6-month follow-up, there were 20 subjects in the intervention group and 17 in the control group. The subjects underwent a clinical examination and completed a neurocognitive test battery. Group comparisons of neuropsychological test scores at follow-up were examined using ANCOVAs and the covariates “age” and “baseline test score”. Correlations between neurocognitive test scores and leptin concentration were examined using partial correlations also controlling for age. Results: 6 months after the surgery, bariatric surgery patients did not exhibit significantly improved learning ability compared to obese controls, though there was a significantly improved learning in the intervention group compared to baseline (p = ,016). Furthermore, there was a significant improvement in the interference task in the intervention group, compared to obese controls (p = ,032). There was a negative correlation between the leptin concentration and learning at baseline (r = -,411, p = ,009). After the surgery, there was a positive correlation between the improvement in the interference task and reduction of leptin (r = ,705, p = ,001). An explorative analysis of surgery subgroups revealed that patients who underwent Roux-en-Y-Gastric-Bypass (n = 7) lost significantly more weight than Vertical-Sleeve-Gastrectomy-Patients (n = 12) and showed better performance in several cognitive domains including resistance to interference, learning and delayed recall. Conclusion: There was no improvement of learning following bariatric surgery, however, there was an improvement of executive functions. These results should now be confirmed in larger studies. Especially studies with follow-up periods extending over decades could help clarify, whether bariatric surgery helps reduce the risk of dementia. The role of leptin could not be completely clarified. Possibly the leptin resistance persisted at follow-up and leptin could not exhibit its neuroprotective effects properly. Therefore, future studies should focus on molecular mechanisms of leptin resistance and its reversibility

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

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 &amp;lt; 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 short-term outcome. Paying attention to accompanying clinical signs is of importance as they may facilitate a timely diagnosis