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patients68. Cerebellar atrophy has been observed in association with both generalised and focal
seizures and in studies of patients with TLE; 46% cerebellar volume reductions have been
shown using MRI69. Neuropathological findings at post mortem may disclose preferential
symmetrical atrophy of the anterior lobes or the more common pattern involving the posterior
lobes70. In mild cases damage may be restricted to a folium and in severe cases more generalised
atrophy is observed. Crossed cerebellar atrophy (cerebellar diaschisis) is also recognised in
patients with contralateral destructive cerebral hemispheric lesions associated with seizures,
including hemiatrophy.

Regardless of the lobar distribution, the histological findings are Purkinje cell loss, Bergman
gliosis in the cortex, relative preservation of basket cells, and granule cell damage. Occasional
torpedo-like axonal swellings on Purkinje cells may be observed. The cause of the cerebellar
atrophy has been attributed to seizure activity (in particular episodes of status epilepticus[71]),
antiepileptic drug (AED) toxicity (in particular phenytoin), hypoxic-ischaemic injury, trauma as
a result of seizures70 or trans-neuronal degeneration (particularly for the crossed cerebellar
pattern). In support of a seizure-induced pathogenesis, atrophy was documented before the
introduction of anticonvulsant medications, and the observation of acute necrosis of the Purkinje
cells following status (occasionally with a crossed pattern) implicates excitotoxicity. Phenytoin
has been shown to cause cerebellar atrophy following acute and chronic administration70, and
experimental toxicity to Purkinje cells and granule cells has been shown72,73. There is no
consistent relationship between seizure frequency and duration and the degree of atrophy to argue
for either process68–71. The observation that crossed atrophy may occur in the absence of seizures
would favour trans-synaptic degeneration via cerebro-cerebellar pathways. In fact, all these
mechanisms may be acting synergistically and may not easily be separated. Typically there are
few clinical symptoms attributable to the atrophy but mild cognitive deficits may occur74. Seizure
control post temporal lobectomy was shown not to be influenced by the presence of cerebellar
atrophy in one75 but not another76 study.