Alcoholic cerebellar degeneration

Alcoholic cerebellar degeneration is a common type of acquired cerebellar ataxia characterised by chronic vermian atrophy ¹. It is a sequela of chronic alcohol use or malnutrition.

Terminology

Alcoholic cerebellar degeneration has also been described in the literature as alcohol-related cerebellar degeneration, alcohol-induced cerebellar degeneration and nutritional cerebellar degeneration ^1,2.

Epidemiology

The prevalence is estimated at 12 – 27% from autopsies ².

Risk factors are those conditions predisposing to malnutrition, including chronic alcohol use ². Regarding alcohol use, the duration of excessive use is likely the main factor ^3-5.

Clinical presentation

Gait ataxia is the primary manifestation owing to predominant involvement of the anterosuperior cerebellar vermis. Other clinical features include ²:

• coarse tremor

• truncal instability

• nystagmus

• lower limb ataxia

• upper limb ataxia (in severe cases)

Pathology

The exact pathogenesis is yet to be elucidated but it is commonly thought to arise from either alcohol neurotoxicity, nutritional deficiency (notably thiamine) or a combination of both ^1,6.

Despite its current name, alcohol may not necessarily be a prerequisite as similar clinicopathological findings have been described in durations of abstinence or in malnourished non-alcoholics ^2,6. Hence it is no wonder that alternative terms have been adopted in the literature.

Histologically, there is Purkinje cell loss in the cerebellar cortex accompanied by Bergmann gliosis, and a variable loss of the molecular layer and granule cells ⁷. Associated neuronal loss in the dorsal inferior olivary nuclei may also be present. The underlying cerebellar white matter is otherwise preserved ⁷.

Radiographic features

CT

Findings are similar to those in MRI.

MRI

Abnormalities are best demonstrated on sagittal views of T1-weighted images ². Midline cerebellar structures are primarily involved.

Early features consist of cerebellar volume loss localised to the anterior superior vermis (lingula, central lobule, culmen, declive) and associated widening of inter-folial sulci ^2,7,8. Subsequent progression to involve the posterior inferior vermis and anterior lobes of the cerebellum can occur ⁸.

These features may occur in isolation or in the presence of other radiographic abnormalities associated with chronic alcohol use, such as those in Wernicke encephalopathy ⁷. Correlation of radiographic findings with the clinical presentation is crucial as vermian atrophy can be present in asymptomatic individuals ².

PET

FDG studies may exhibit hypometabolism in similarly affected areas of the cerebellum ⁹.

Treatment and prognosis

Treatment is targeted towards abstinence, nutritional supplementation and gait optimisation ².

Improvement varies with the degree of abstinence and dietary repletion, although gait ataxia can be persistent in severe cases ².

Differential diagnosis

Alcoholic cerebellar degeneration should be distinguished from cerebellar hypoplasia and other forms of cerebellar atrophy.