Cerebral peduncular infarction

Rare presentation of an isolated bilateral cerebral peduncular infarction: A case report and review of the literature

RATIONALE

Due to the rarity of bilateral cerebral peduncular infarction (BCPI), its symptoms and prognosis are not clear. It is necessary to collect cases of pure cerebral peduncular infarction, explore the etiology and anatomy of midbrain infarction in depth, and develop meaningful tools for explaining clinical symptoms and predicting prognosis of patients.

PATIENT CONCERNS

We here provide a case of isolated BCPI with uncommon symptoms of ataxia, dysarthria, sensory disturbance, normal muscular strength, and full eye movements.

DIAGNOSES

Diffusion weighted images and apparent diffusion coefficient map of our patient revealed acute and isolated bilateral peduncle cerebrum infarction.

INTERVENTIONS

Drugs that could improve circulation and antiplatelet were used in therapy.

OUTCOMES

The infarct size was enlarged and new infarction was identified in the splenium of the corpus callosum and pons. The patient developed progressed disorder of consciousness and died at the eleventh day.

LESSONS

We inferred that the symptoms of ataxia, dysarthria, sensory disturbance, and mild paresis of the extremities could be prominent features of patients with pure cerebral peduncular infarction. We hypothesize that pure BCPI is also related to severe basilar artery stenosis or occlusion and there is no collateral circulation from PCA. This may explain the corresponding distribution of cerebral peduncular infarction and its poor prognosis. For these reasons, exploring etiology and anatomy of midbrain infarction in depth would have clinical value for predicting symptoms and prognosis.

Peduncular hallucinosis

Peduncular hallucinosis (PH) is a syndrome of hallucinations and brainstem symptoms which has only been described in single case reports. A detailed analysis of five patients was undertaken to investigate the clincial characteristics, hallucinations and behavioural abnormalities of PH in greater detail. Frequent clinical symptoms were oculomotor disturbances, impaired arousal, dysarthria and ataxia. In the chronic stage, sleep-wake cycle disturbances were common. Hallucinations were naturalistic, complex, scenic, mostly visual, but also combined visual-acoustic or visual-tactile and recurred stereotypically over months. Patients experienced their hallucinations as genuine and were unable to discriminate their percepts from reality. Neuropsychological testing disclosed severe impairments of episodic memory, occasionally coupled with confabulatory behaviour. By contrast, memory for hallucinations remained intact. Deficits of attentional and executive functions were found in a subgroup of patients. Associated abnormal behaviours were common, comprising confusion, delusional misidentification for persons and places, and loss of disease awareness. PH appeared after focal lesions in various regions, such as the midbrain, thalamus and pons. These findings document that subcortical, brainstem-related hallucinations are vivid, recurring percepts that have a strong naturalistic character and are often associated with cognitive and behavioural abnormalities. It seems likely that brainstem hallucinosis is caused by damage to ascending reticular systems and thalamocortical circuits. Available observations suggest that PH compromises cognitive functions which enable us to differentiate between illusionary percepts and reality, a reality monitoring system.