Paramedian Thalamic Ischemic Infarction: A Retrospective Clinical Observation

Distinct alterations of retinal structure between thalamic and extra-thalamic subcortical infarction patients: A cross-sectional and longitudinal study

AIMS

Cerebrovascular lesions in the primary visual cortex, the lateral geniculate nucleus, and the optic tract have been associated with retinal neurodegeneration via the retrograde degeneration (RD) mechanism. We aimed to use optical coherence tomography (OCT) to assess the effects of the strategic single subcortical infarction (SSI) location on retinal neurodegeneration and its longitudinal impacts.

METHODS

Patients with SSI were enrolled and stratified by lesion location on cerebral MRI into the thalamic infarction group and extra-thalamic infarction group. Healthy controls from the native communities were also recruited. Retinal nerve fiber layer (RNFL) and ganglion cell-inner plexiform layer (GCIPL) were quantified using OCT. Generalized estimating equation (GEE) models were used for cross-sectional analyses and linear mixed models for longitudinal analyses. P < 0.05 was considered statistically significant.

RESULTS

We included a total of 283 eyes from 149 SSI patients. Of these, 115 eyes of 60 patients with follow-up were included in the longitudinal analyses. Cross-sectionally, thalamic-infarction patients had reduced retinal thickness compared with extra-thalamic infarction patients after adjustment for age, gender, disease duration, and vascular risk factors (p = 0.026 for RNFL, and p = 0.026 for GCIPL). Longitudinally, SSI patients showed greater retinal thinning compared with healthy controls over time (p = 0.040 for RNFL, and p < 0.001 for GCIPL), and thalamic infarction patients exhibited faster rates of GCIPL thinning in comparison with extra-thalamic infarction patients (p < 0.001).

CONCLUSION

Our study demonstrates a distinct effect of subcortical infarction lesion site on the retina both at the early stage of disease and at the 1-year follow-up time. These results present evidence of significant associations between strategic infarction locations and retinal neurodegeneration. It may provide novel insights for further research on RD in stroke patients and ultimately facilitate individualized recovery therapeutic strategy.

Agitation and somnolence by bilateral paramedian thalamic infarct

Key Clinical Message

Bilateral thalamic infarction in paramedian artery territory may present with severe acute illness, confusion, coma and memory impairment. However, subtle clinical presentation as in our case should alert the clinician to consider such a diagnosis as it can be associated with good prognosis.

Abstract

Bilateral thalamic infarct is a rare form of stroke. Mostly thalamic infarcts are unilateral. In most cases, bilateral thalamic infarction leads to cognitive dysfunction, opthalmoparesis, conscious impairment, behavioral disturbance, and corticospinal dysfunction. Here, we describe the case of a 75-year-old male patient who presented to the emergency department of our hospital with agitation and somnolence for one day. He had poorly controlled hypertension. There was no previous history of stroke, diabetes mellitus, hyperlipidemia, known cardiac disease, or smoking history. There was no seizure, recent headache, or visual disturbance. The patient was somnolent and not oriented to time, person, or place. Neurological examination did not show any focal weakness or vertical eye movement restrictions. Other systemic examinations, including those of the respiratory and cardiovascular systems, were unremarkable. Extensive laboratory investigations excluded potential metabolic, infectious, endocrine, or toxic etiologies. The patient did not have any recent history of drug misuse, including benzodiazepines. Brain MRI with diffusion-weighted imaging showed an acute bilateral thalamic infarct. Cerebral angiography was unremarkable. The patient was treated with low molecular weight heparin 60 mg subcutaneously, aspirin 300 mg daily, and haloperidol 5 mg twice daily for agitation. After two weeks of intrahospital treatment, his condition improved (consciousness and orientation massively improved).

Distribution of the Noradrenaline Innervation and Adrenoceptors in the Macaque Monkey Thalamus

Noradrenaline (NA) in the thalamus has important roles in physiological, pharmacological, and pathological neuromodulation. In this work, a complete characterization of NA axons and Alpha adrenoceptors distributions is provided.

NA axons, revealed by immunohistochemistry against the synthesizing enzyme and the NA transporter, are present in all thalamic nuclei. The most densely innervated ones are the midline nuclei, intralaminar nuclei (paracentral and parafascicular), and the medial sector of the mediodorsal nucleus (MDm). The ventral motor nuclei and most somatosensory relay nuclei receive a moderate NA innervation. The pulvinar complex receives a heterogeneous innervation. The lateral geniculate nucleus (GL) has the lowest NA innervation.

Alpha adrenoceptors were analyzed by in vitro quantitative autoradiography. Alpha-1 receptor densities are higher than Alpha-2 densities. Overall, axonal densities and Alpha adrenoceptor densities coincide; although some mismatches were identified. The nuclei with the highest Alpha-1 values are MDm, the parvocellular part of the ventral posterior medial nucleus, medial pulvinar, and midline nuclei. The nucleus with the lowest Alpha-1 receptor density is GL. Alpha-2 receptor densities are highest in the lateral dorsal, centromedian, medial and inferior pulvinar, and midline nuclei.

These results suggest a role for NA in modulating thalamic involvement in consciousness, limbic, cognitive, and executive functions.

Topographic evaluation of bithalamic infarcts: Are these due to occlusion of the artery of Percheron?

Occlusion of the artery of Percheron (AoP) causes bithalamic paramedian infarct (BTPI). Although it can be diagnosed easily in its pure form, it can be underdiagnosed in cases with concomitant extrathalamic acute infarcts (plus-BTPI) as it may be difficult to determine whether BTPI is due to occlusion of AoP or two different paramedian arteries even with conventional angiography. This study was performed to highlight plus-BTPI that could result from occlusion of AoP rather than of two distinct paramedian arteries using topographic evaluation of bithalamic infarcts. We retrospectively reviewed imaging and clinical databases for patients admitted to radiology department between 2013 and 2019. Two radiologists independently evaluated the results of imaging studies, and findings reached by consensus were used in the analysis. This retrospective review yielded 34 patients with bithalamic infarct. Each affected thalamic vascular region was investigated separately. Any patient could have more than 2 different vascular zone infarct. The affected thalamic vascular territories were paramedian (n = 24), inferolateral (n = 13), anterior (n = 10), and posterior (n = 7). When we evaluated bithalamic infarcts in terms of symmetrically affected territories, the distribution of symmetric affected territories was as: paramedian (n = 18), inferolateral (n = 2), anterior (n = 1), and posterior (n = 1). BTPI had a 4.5-fold higher frequency than the sum of symmetric involvement of other territories (p = 0.0552, OR = 4.5,95%CI 0.93-21.5). In addition, mesencephalic involvement was only observed in BTPI, and not in other patterns (p < 0.001). The fact that in bilateral thalamic infarcts the symmetric involvement of paramedic territory is significantly higher and mesencephalic involvement is seen only in BTPI can suggest that plus-BPTI may develop due to AoP occlusion rather than occlusion of two distinct paramedian arteries.

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.

Neuro-Ophthalmologic Features and Outcomes of Thalamic Infarction: A Single-Institutional 10-Year Experience

BACKGROUND

Neuro-ophthalmologic deficit after thalamic infarction has been of great concern to ophthalmologists because of its debilitating impacts on patients' daily living. We aimed to describe the visual and oculomotor features of thalamic infarction and to delineate clinical outcomes and prognostic factors of the oculomotor deficits from an ophthalmologic point of view.

METHODS

Clinical and neuroimaging data of all participants were retrospectively reviewed. Among the 12,755 patients with first-ever ischemic stroke, who were registered in our Stroke Data Bank between January 2009 and December 2018, 342 were found to have acute thalamic infarcts on MRI, from whom we identified the patients exhibiting neuro-ophthalmologic manifestations including visual, oculomotor, pupillary, and eyelid anomalies.

RESULTS

Forty (11.7%) of the 342 patients with thalamic infarction demonstrated neuro-ophthalmologic manifestations, consisting of vertical gaze palsy (n = 19), skew deviation with an invariable hypotropia of the contralesional eye (n = 18), third nerve palsy (n = 11), pseudoabducens palsy (n = 9), visual field defects (n = 7), and other anomalies such as isolated ptosis and miosis (n = 7). Paramedian infarct was the most predominant lesion of neuro-ophthalmologic significance, accounting for 84.8% (n = 28) of all patients sharing the oculomotor features. Although most of the patients with oculomotor abnormalities rapidly improved without sequelae, 6 (18.2%) patients showed permanent oculomotor deficits. Common clinical features of patients with permanent oculomotor deficits included the following: no improvement within 3 months, combined upgaze and downgaze palsy, and the involvement of the paramedian tegmentum of the rostral midbrain.

CONCLUSIONS

Thalamic infarction, especially in paramedian territory, can cause a wide variety of neuro-ophthalmologic manifestations, including vertical gaze palsy, skew deviation, and third nerve palsy. Although most oculomotor abnormalities resolve spontaneously within a few months, some may persist for years when the deficits remain unimproved for more than 3 months after stroke.