The most severe form of neurologic alterations is known as De Sanctis-Cacchione syndrome: including classical XP manifestations plus hyporeflexia or areflexia, microcephaly
[freethesaurus.com]
In a review of 830 cases of XP, Kraemer et al. (1987) found that 18% had neurologic abnormalities, including progressive mental deterioration, hyporeflexia or areflexia, and
[findzebra.com]
The problems include microcephaly, spasticity, hyporeflexia or areflexia, ataxia, chorea, motor neuron signs or segmental demyelination, sensorineural deafness, supranuclear
[aocd.org]