What are the characteristics of infarcts in different parts of the cerebellum?

Introduction Dizziness, vertigo, and ataxia are common symptoms of posterior circulation ischemia, among which cerebellar stroke is the hardest hit area for these symptoms
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Compared with stroke in the cerebral hemisphere, cerebellar stroke is more likely to be misdiagnosed, so it is important to understand the symptoms of infarction in different blood supply regions of the cerebellum
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This article summarizes the characteristics of infarcts in different parts of the cerebellum for your reference
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Compiled and organized by Yimaitong, please do not reprint without authorization
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Overview of blood supply to the cerebellum The cerebellum is supplied by the posterior inferior artery (PICA), anterior inferior artery (AICA), and superior artery (SCA) (Figure 1)
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In central vascular vertigo syndrome, cerebellar stroke ranks first among all causes, and studies have shown that about 11% of patients with isolated cerebellar infarction have vertigo as the only symptom, most of which are infarcted in the medial branch of PICA.

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Figure 1 Schematic diagram of blood supply to the cerebellum 10% to 25% of patients with cerebellar infarction may have mass effect, and infarction in the PICA area is more likely to cause mass effect than infarction in the SCA area
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Large cerebellar infarcts can result in compression of the brain stem, leading to hydrocephalus, cardiopulmonary complications, coma, and death
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Therefore, correct identification of cerebellar stroke is very important for subsequent treatment, especially in the acute phase
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Posterior inferior cerebellar artery blood supply area infarction PICA is the main blood supply to the cerebellum
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Because vestibular cerebellum structures, such as cerebellar nodules and vermis, supply blood to PICA, so patients with cerebral infarction in the PICA blood supply area are often accompanied by dizziness and imbalance
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Patients usually do not have significant cerebellar signs, such as dysarthria and limb paralysis, and in such patients, detailed neurological evaluation is required, especially in patients with medial branch of PICA infarction
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In fact, approximately 17% of patients with PICA infarction have symptoms that mimic the features of acute peripheral vestibular lesions
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In a study of 72 patients with cerebellar infarcts, most of them PICA infarcts, 39% of these patients developed spontaneous nystagmus
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Although severe imbalance (71%) and gaze-evoked nystagmus with variable orientation (54%) were also present, the sensitivity and specificity of these symptoms and signs were not ideal, and only about half of the patients had central vestibular symptoms signs of dysfunction
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In contrast, in order to better define the cause of acute spontaneous vertigo syndrome, the head impulse test (HIT) is useful in differentiating cerebellar infarcts in the PICA supply area from inner ear disease
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One study showed that in patients with isolated vertigo due to PICA infarction, bedside HIT results were always negative
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In addition, the structures involved in unidirectional gaze-induced nystagmus include the vermis cone, vermis, and cerebellar tonsils.
Gaze-induced nystagmus may also be a sign of damage to the midline and lower cerebellar structures
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The diagnostic role of vestibular evoked myogenic potentials (VEMPs) in the diagnosis of cerebellar infarction has been controversial
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The HINTS test, which includes the head impulse test (head impulse test), nystagmus, and the cross-eye occlusion test, can help differentiate central from peripheral causes
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For the details of the HINTS examination, please refer to: "Teach you the physical examination of dizzy and dizzy patients"
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Anterior inferior cerebellar artery infarction AICA supplies blood to peripheral and central vestibular structures, including the inner ear, lateral pons, and middle cerebellar peduncle
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Therefore, AICA infarction usually results in peripheral and central vestibular lesions
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Patients with infarcts in the AICA supply area mainly present with a combination of symptoms including dizziness/vertigo, nystagmus, hearing loss, loss of limb and facial sensation, ataxia, and dysmetria
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When the pontine medulla is involved, AICA stroke can present with ipsilateral upper and lower facial weakness
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Although less common than PICA infarction, AICA infarction can cause sudden vertigo and ipsilateral sensorineural hearing loss due to ischemia of the vestibulocochlear nerve and inner ear supplied by the labyrinthine artery
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Hearing loss detected during the acute phase of infarction usually resolves over time
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Inner ear dysfunction may precede infarction in the cerebellar tissue supplied by the AICA, possibly because the inner ear or brainstem vestibular structures are relatively more vulnerable to ischemia
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According to the manifestations of the nervous system, some scholars have proposed 8 subtypes of AICA infarction, of which auditory and vestibular loss are the most common
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However, the diagnosis of AICA-supplied infarction remains a challenge, especially when symptoms and signs other than inner ear infarction are absent or obscure
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It should be noted that the HINTS test, although one of the most useful tests for the detection of central vestibular lesions, may be underpowered for AICA infarcts
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In one study, central lesions were not detected by HINTS in 5 of 18 patients with AICA infarction
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Therefore, in order to further improve the diagnostic accuracy, other examinations, such as shaking head-induced nystagmus, may be required
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Superior cerebellar artery infarction Since the SCA supplies blood to the caudal midbrain and posterior cerebellum, ipsilateral trochlear palsy, Horner syndrome, and contralateral ataxia can be observed in infarcts in the SCA supply area
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However, midbrain involvement is rare in SCA infarcts, and the classic presentation of trochlear nerve palsy + Horner syndrome + ataxia is rare in patients with SCA infarction
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Cerebellar infarction in the SCA-supplied area rarely causes vertigo because the upper cerebellum supplied by the SCA has no significant vestibular structure
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However, a recent study showed that approximately half of patients with isolated SCA infarction had symptoms of vertigo, and 27% of patients had spontaneous nystagmus or gaze-evoked nystagmus, and SCA infarction was seen to be more vertigo and nystagmus than ever before.
more common as people think
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Infarction of the medial branch of unilateral SCA can cause saccadic eyeballs with excessive saccade to the contralateral side and too small saccade to the ipsilateral side, and can cause poor distance discrimination of the ipsilateral limb
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Patients with infarcts involving the superior cerebellar peduncle alone showed symptoms such as ocular torsion, mild dysarthria, and ipsilateral limb ataxia, but no abnormal saccades
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Summary The characteristics of infarcts in each blood supply area of ​​the cerebellum are summarized in the table below
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References: [1] Choi KD, Lee H, Kim J S.
Ischemic syndromes causing dizziness and vertigo[J].
Handbook of Clinical Neurology, 2016, 137:317.
[2] Southerland A M.
Clinical Evaluation of the Patient With Acute Stroke[J].
Continuum Lifelong Learning in Neurology, 2017, 23(1):40-61.