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Table 2 Characteristics of seizures, EEG pattern and EP study results

From: The neurology of rhizomelic chondrodysplasia punctata

Patient Age at epilepsy onset, y Seizure type Seizure frequency Age at EEG examination, y Background pattern first EEG/development of background pattern Focal/multifocal abnormal activity Epileptiform activity Age at EP examination, y BAEP VEP SSEP
1 2 Myoclonic Daily 2.0-4.2 M ➔ Mo Focal + 3.1 – 4.2 N ➔ N N ➔ N -
2 11 Myoclonic; generalized tonic-clonic Weekly 0.8-11.7 N ➔ S Focal + (≥ 3.8 yrs) 0.8 - 9.1 N ➔ S N ➔ S NCR
3 4 1. Fever induced generalized tonic-clonic; 2. (>8.5 yrs) generalized tonic-clonic and atypical absence 1. Sporadic; 2. Weekly 0.8-8.6 N ➔ S Multifocal + (≥ 2.9 yrs) 0.8 - 6.9 N ➔ S N ➔N N ➔ M
4 0.3 Tonic; smacking Daily 0.0-1.3 N ➔ S Multifocal + (≥ 0.5 yrs 0 - 0.3 N ➔ S N ➔N -
5 3 Myoclonic; gelastic; atypical absence Daily 0.9-4.5 M ➔ Mo Focal ➔ multifocal + (≥ 0.9 yrs) 1.3 - 4.5 N ➔ M N ➔ M NCR/S
6 2 Myoclonic; status epilepticus Daily (clustered) 0.2-2.4 N ➔ S Focal ➔ multifocal + (≥ 1.1 yrs) St epilepticus 0.2 - 2.3 N ➔ N N ➔ N NCR
7 2 Myoclonic-tonic; gelastic Daily 0.0-4.0 N ➔ M   + (≥ 2.3 yrs) 0 -1.8 N N ➔ N N
8 0.8 Tonic Fever induced 0.0-2.2 N    0 N M -
9 1 Generalized tonic-clonic Single, fever induced 0.7-1.7 N ➔ M Multifocal + (≥1.1 yrs) 0.5 - 1.7 N ➔ N N ➔N -
10 5 1. Facial myoclonic; 2. tonic 1. Daily; 2. Monthly 5.6 N Focal + - - - -
11     0.3 M   + 0.3 N N M
12 10 Myoclonic Daily 26.7 M Focal + - - - -
13     5.4-7.3 N ➔ N Focal + (≥ 5.4 yrs) 5.4 - 7.3 N ➔ N N ➔ N N ➔ N
14 7 Atypical absences Weekly 6.5-8.3 M   + (≥ 6.5 yrs) 6.5 - 7.5 N ➔ N M ➔ N N ➔ N
15 21 Generalized tonic-clonic Single 9.3-23.1 M Focal➔ multifocal + (21 yrs) 9.3 - 23.1 N ➔ N N ➔ M N
16 20 Atypical absence Monthly 13.3-29.5 Mo ➔ Mo Multifocal + (≥ 13.3 yrs) 10 - 17 N N ➔ N -
  1. N: normal; M: mildly abnormal EEG for age/mildly increased latencies (+2-4 SD), Mo: moderately abnormal EEG background pattern, S: severely abnormal EEG pattern for age/markedly increased latencies (> +4 SD). NCR: no cortical response, y: years.