These disorders include: classical stiff-person syndrome and variants, cerebellar ataxia, limbic and extra-limbic encephalitis, nystagmus/oculomotor dysfunction, drug-resistant epilepsy, paraneoplastic stiff-person syndrome and progressive encephalopathy with rigidity and myoclonus (PERM), the latter two are mainly related to amphiphysin and the glycine receptor Abs respectively; but patients may also have positive GAD-Abs.
These include anti-N-methyl-d-aspartate receptor (NMDAR) encephalitis which may present with orolingual facial dyskinesia and stereotyped movements, CRMP-5 IgG presenting with chorea, anti-Yo paraneoplastic cerebellar degeneration presenting with ataxia, anti-VGKC complex (Caspr2 antibodies) neuromyotonia, opsoclonus-myoclonus-ataxia syndrome, and muscle rigidity and episodic spasms (amphiphysin, glutamic acid decarboxylase, glycine receptor, GABA(A)-receptor associated protein antibodies) in stiff-person syndrome.