Consensus Paper: Revisiting the Symptoms and Signs of Cerebellar Syndrome

Abstract

The cerebellum is involved in sensorimotor operations, cognitive tasks and affective processes. Here, we revisit the concept of the cerebellar syndrome in the light of recent advances in our understanding of cerebellar operations. The key symptoms and signs of cerebellar dysfunction, often grouped under the generic term of ataxia, are discussed. Vertigo, dizziness, and imbalance are associated with lesions of the vestibulo-cerebellar, vestibulo-spinal, or cerebellar ocular motor systems. The cerebellum plays a major role in the online to long-term control of eye movements (control of calibration, reduction of eye instability, maintenance of ocular alignment). Ocular instability, nystagmus, saccadic intrusions, impaired smooth pursuit, impaired vestibulo-ocular reflex (VOR), and ocular misalignment are at the core of oculomotor cerebellar deficits. As a motor speech disorder, ataxic dysarthria is highly suggestive of cerebellar pathology. Regarding motor control of limbs, hypotonia, a- or dysdiadochokinesia, dysmetria, grasping deficits and various tremor phenomenologies are observed in cerebellar disorders to varying degrees. There is clear evidence that the cerebellum participates in force perception and proprioceptive sense during active movements. Gait is staggering with a wide base, and tandem gait is very often impaired in cerebellar disorders. In terms of cognitive and affective operations, impairments are found in executive functions, visual-spatial processing, linguistic function, and affective regulation (Schmahmann’s syndrome). Nonmotor linguistic deficits including disruption of articulatory and graphomotor planning, language dynamics, verbal fluency, phonological, and semantic word retrieval, expressive and receptive syntax, and various aspects of reading and writing may be impaired after cerebellar damage. The cerebellum is organized into (a) a primary sensorimotor region in the anterior lobe and adjacent part of lobule VI, (b) a second sensorimotor region in lobule VIII, and (c) cognitive and limbic regions located in the posterior lobe (lobule VI, lobule VIIA which includes crus I and crus II, and lobule VIIB). The limbic cerebellum is mainly represented in the posterior vermis. The cortico-ponto-cerebellar and cerebello-thalamocortical loops establish close functional connections between the cerebellum and the supratentorial motor, paralimbic and association cortices, and cerebellar symptoms are associated with a disruption of these loops.

Neurodegeneration and the Cerebellum

“…This area controls many vestibular functions related to the inner ear, such as the vestibular-ocular reflex, such that lesions in this area cause vertigo/dizziness, imbalance [19], equilibrium disturbances, gait ataxia, and wide-based gait and posture [18]. Symptoms are attributable to acute, chronic, or recurrent injury, depending on the type of lesion present (e.g., acute - stroke; chronic - tumors; recurrent - episodic ataxias) [19]. …”

“…Lobule X lesions result in nystagmus, typically in the downbeat direction (slow drift upwards and a quick corrective downward saccade) [21]. Lesions of the oculomotor vermis show saccadic deficiencies and impaired smooth pursuit [18,19,22,23]. …”

“…The paravermal, intermediate, and lateral regions of the cerebellar cortex are implicated in ataxic dysarthria and speech [19]. Lateral hemispheres are also involved in eye-blink conditioning [10], complex and skilled movements, and motor actions, where complex movements require precise timing, judgment, and coordination.…”

Neurocognitive Characterization of an SCA28 Family Caused by a Novel AFG3L2 Gene Mutation

“…This may reflect the disturbance of the cerebellar-prefrontal connection system [33,34] [39,40]. This syndrome is supposed to derive from the disruption of cerebellar neural circuits linking the cerebellum to prefrontal, posterior parietal, superior temporal and limbic cortical areas, typically leading to deficits in executive and visuospatial functions, language and emotional regulation [41]. There is a varying severity of the symptoms in patients with the same cerebellar pathology.…”

Physical Therapy for Cerebellar Ataxia

“…The cerebellum contributes to sensory motor control [3,[19][20][21][22][23][24][25], gait [11,21,[26][27][28][29][30][31], and balance [5] for maintenance of upright posture. Furthermore, the cerebellum has an important role in motor learning [32] and adaptation [33].…”