Neuropsychological profile of bilateral paramedian infarctions: three cases

Clinical Analysis of Bilateral Thalamic Infarction Caused by Percheron Artery Occlusion

The Percheron artery (artery of Percheron, AOP) is a rare variant vessel. Its acute occlusion can cause a bilateral symmetrical thalamic stroke; typical symptoms of bilateral paramedian thalamic infarcts due to occlusion of AOP are vertical gaze palsy, memory impairment, confusion, drowsiness, hypersomnolence, or coma. We present the MR imaging findings in two cases with cerebral infarction caused by Percheron artery occlusion. Due to the difficulty in the diagnosis of acute Percheron arterial infarction, early conservative treatment is used. The prognosis of the disease is poor, with few patients completely rehabilitating. Therefore, clinicians must understand the characteristics of the disease, provide early diagnosis and administer timely and effective treatment to reduce the patient's disability rate and fatality rate and therefore improve the quality of life of patients. The patient's prognosis has extraordinary significance.

Artery of Percheron infarction with persistent amnesia: a case report of bilateral paramedian thalamic syndrome

Background

The artery of Percheron is an uncommon anatomic variant which supplies the bilateral paramedian thalami and rostral midbrain. While infarction of its vascular territory can result in a wide range of symptoms, paramedian thalamic syndrome is classically described as a triad of symptoms including vertical gaze disturbances, fluctuating level of consciousness, and amnesia. There is minimal evidence to date to characterize the long-term cognitive consequences of infarction of the artery of Percheron utilizing neuropsychological assessment.

Case presentation

We describe a 40-year-old female patient initially presenting with dizziness, confusion and falls with unremarkable head CT scans. Subsequent MRI, more than 24 h after symptom onset, identified evidence of bilateral thalamic and rostral midbrain infarction. Neuropsychological testing was administered at 4 months post-stroke, with follow up testing at 1 year. The patient was found to have profound anterograde and retrograde amnesia, which did not change significantly over the first year of rehabilitation, and which was not easily identifiable in everyday encounters due to her relatively intact working memory and social skills.

Conclusions

As early diagnosis of infarction of the artery of Percheron is challenging, patients have frequently missed the time window for acute management of ischemic stroke. Moreover, this case study highlights the need for further research in deciphering the role of the paramedian thalamus in memory and cognition, as well as the importance of standardized neuropsychological testing for the artery of Percheron stroke patients to identify safety and rehabilitation concerns that may be overlooked.

Fluctuating drowsiness following cardiac catheterisation: artery of Percheron ischaemic stroke causing bilateral thalamic infarcts

An 81-year-old man underwent cardiac catheterisation to investigate breathlessness and left ventricular impairment of unknown cause. He had unobstructed coronary arteries. Immediately following the procedure, he became suddenly unresponsive with vertical gaze palsy, anisocoria and bilateral upgoing plantar responses. He made a rapid recovery to his premorbid state 25 min later with no residual focal neurological signs. He then had multiple unresponsive episodes, interspaced with complete resolution of symptoms and neurological signs. MRI of the brain identified bilateral medial thalamic infarcts and midbrain infarcts, consistent with an artery of Percheron territory infarction. By the time the diagnosis was reached, the thrombolysis window had elapsed. The unresponsive episodes diminished with time and the patient was discharged to inpatient rehabilitation. At 6-month review after the episode, the patient has a degree of progressive cognitive impairment.

Acute Occlusion of the Percheron Artery during Pregnancy: A Case Report and a Review of the Literature

OBJECTIVES

The Percheron artery (PA) is a rare variant vessel. Its acute occlusion can cause a bilateral symmetrical thalamic stroke, clinically manifested as a sudden alteration of consciousness that could vary from sleepiness to coma. In this paper, we illustrate a case of acute PA occlusion in a young, pregnant woman and present a review of the literature, focusing on the possible causes of the acute occlusion.

METHODS

A 35-year-old woman, at the fourth week of pregnancy, came to the emergency department of our hospital because of a sudden onset and persistent loss of consciousness. Brain magnetic resonance imaging (MRI) showed a symmetrical and bilateral thalamic infarction without evidence of other ischemic lesions, compatible with an acute PA occlusion.

RESULTS

The patient, who showed full clinical recovery within a few hours of symptom onset, received a short-term anticoagulant treatment followed by aspirin for long-term prevention.

CONCLUSIONS

We reviewed the literature about the possible causes of acute PA occlusion. This ischemic condition is usually associated with cardioembolic or small-vessel disease. However, in our patient, we did not find any element supportive for coagulative alteration or embolyzing conditions.

PRACTICE

The presence of this type of thalamic stroke should be considered in the management of persistent loss of consciousness. PA occlusion is rare, but it needs a brain MRI examination for a correct diagnosis, a narrow evaluation of all the possible causes, and a long-term anticoagulant therapy. Pregnancy itself should constitute a rare but possible cause of a PA occlusion.

Decreased consciousness: bilateral thalamic infarction and its relation to the artery of Percheron

This case series highlights two patients seen in the same stroke centre presenting with unusual symptoms. They were later diagnosed with bilateral thalamic infarcts, probably related to an unusual anatomical variant. The difficulties in establishing the diagnoses due to their relative rarity and complexity could have impacted on patient outcomes.

Cognitive and behavioral deficits following bilateral thalamic stroke: a longitudinal study

We describe behavioral and neuropsychological outcome of a patient (N.S.), who showed a bilateral paramedian thalamic ischemic lesion, with particular reference to the longitudinal evolution of topographical disorientation (TD) and confabulations. We report clinical neuropsychological/behavioral data over a 43-month follow-up. The results show early after the stroke a severe amnesic-confabulatory syndrome with dysexecutive deficits, associated with memory disorders both for visuo-spatial and verbal materials and TD both for known and new places. Behavioral disinhibition and anosognosia for cognitive deficits were also observed. All cognitive impairments have been recovered during the long-term follow-up. Bilateral paramedian thalamic infarcts often lead to severe and long-lasting neurological and cognitive impairments. Only a few cases showed good recovery. Our patient represents an interesting and uncommon case of bilateral paramedian thalamic syndrome with a significant neuropsychological recovery.

Lesions of the anterior thalamic nuclei and intralaminar thalamic nuclei: place and visual discrimination learning in the water maze

Medial thalamic damage produces memory deficits in humans (e.g., Korsakoff's syndrome) and experimental animals. Both the anterior thalamic nuclei (ATN) and rostral intralaminar plus adjacent lateral thalamic nuclei (ILN/LT) have been implicated. Based on the differences in their main connections with other neural structures, we tested the prediction that ATN lesions would selectively impair acquisition of spatial location discrimination, reflecting a hippocampal system deficit, whereas ILN/LT lesions would impair acquisition of visual pattern discrimination, reflecting a striatal system deficit. Half the rats were first trained in a spatial task in a water maze before switching to a visual task in the same maze, while the remainder were tested with the reverse order of tasks. Compared with sham-operated controls, (1) rats with ATN lesions showed impaired place learning, but normal visual discrimination learning, (2) rats with ILN/LT lesions showed no deficit on either task. Rats with ATN lesions were also hyperactive when their home cage was placed in a novel room and remained more active than ILN/LT or SHAM rats for the subsequent 21 h, especially during the nocturnal phase. These findings confirmed the influence of ATN lesions on spatial learning, but failed to support the view that ILN/LT lesions disrupt striatal-dependent memory.