Differential Diagnosis of Huntington's Disease-like Syndromes
Differential Diagnosis of Huntington's Disease-like Syndromes
In HD, seizures are present only in the juvenile variant, occurring in 30%–50% of patients with onset before age 10. At difference, in a number of progressive HD-like syndromes seizures are relatively common, presenting in 22% of SCA-17 cases, 60% of cases with chorea-acanthocytosis, 40% of cases with McLeod syndrome and the majority of cases with Huntington's disease-like 1 (HDL1) syndrome, a prion disease resembling adult-onset HD (detailed below). Seizures are the initial manifestation in almost half of chorea-acanthocytosis cases. Temporal lobe seizures, even simulating a familial temporal lobe epilepsy, are seen in chorea-acanthocytosis, whereas they are mostly generalised in McLeod syndrome. Seizures are also a cardinal feature of DRPLA, present in virtually all cases with onset before the age of 20, less frequently when onset is between ages 20 and 40, and rarely with onset above the age of 40. Seizures in DRPLA can be tonic, clonic, tonic-clonic, absences, atonic, and in the form of myoclonic epilepsy, with or without a progressive myoclonic epilepsy phenotype. Epilepsy is rare in all the other HD-like syndromes.
Seizures
In HD, seizures are present only in the juvenile variant, occurring in 30%–50% of patients with onset before age 10. At difference, in a number of progressive HD-like syndromes seizures are relatively common, presenting in 22% of SCA-17 cases, 60% of cases with chorea-acanthocytosis, 40% of cases with McLeod syndrome and the majority of cases with Huntington's disease-like 1 (HDL1) syndrome, a prion disease resembling adult-onset HD (detailed below). Seizures are the initial manifestation in almost half of chorea-acanthocytosis cases. Temporal lobe seizures, even simulating a familial temporal lobe epilepsy, are seen in chorea-acanthocytosis, whereas they are mostly generalised in McLeod syndrome. Seizures are also a cardinal feature of DRPLA, present in virtually all cases with onset before the age of 20, less frequently when onset is between ages 20 and 40, and rarely with onset above the age of 40. Seizures in DRPLA can be tonic, clonic, tonic-clonic, absences, atonic, and in the form of myoclonic epilepsy, with or without a progressive myoclonic epilepsy phenotype. Epilepsy is rare in all the other HD-like syndromes.
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