Table 4 Clinical features of six sporadic cases with SCN8A gene mutation

M

1 y, 15 m

2 m

Focal seizure

Head control (15 m), unable to sit alone (1 y, 15 m)

Severe ID

Asynchronous bilateral spike, spike and wave discharges, with central, parietal and frontal predominance (3 m)

None

OXC 30 mg/kg/d, VPA 32 mg/kg/d, CZP 0.6 mg/d; no seizure from 1 y

+

M

2 y, 8 m

3 m

Focal seizure (3 m), myoclonic seizure (9 m)

Head control (2 y, 4 m)

Severe ID

Generalized high amplitude multi-spike and slow waves (9 m)

Normal (3 m); slight widened cerebellar sulci (8 m)

VPA 42 mg/kg/d, LTG 4.5 mg/kg/d, seizure free from 2 y

+

M

3 y, 6 m

3.5 m

Focal seizure, secondary generalized seizure, status epilepticus

Can’t control head at 1-year-old

Severe ID

Diffuse slow waves in the background, spike at right central area during sleep period (1 y)

Normal (3 m)

LEV 29.4 mg/kg, OXC 49.4 mg/kg, TPM 5.9 mg/kg, VPA 23.5 mg/kg; Seizures were not controlled –during follow-up visit (before 1 y)

+

F

2 y, 6 m

4 m

Focal seizure (4 m), generalized seizure (2 y, 2 m)

Head control at age of 2 y, 5 m

Severe ID

Boundary condition (4 m)

Normal (2 y)

Seizures frequency reduced by VPA 36 mg/kg/d, TPM 6.8 mg/kg/d, CZP 0.5 mg/d, and CBZ 18 mg/kg/d

+

F

1 y

5 m

Focal seizure with generalization

Head control (2 m), sit independently (9 m), stand with assistance (1 y)

Normal

sharp and spike waves in the right frontal during sleep period, and 3–4 Hz slow-wave complexes in the occipital during awake period (8 m)

Normal (7 m)

Seizures were controlled by LEV (48.9 mg/kg/d), VPA (26.7 mg/kg/d), OXC 20 mg/kg/d; no seizures were reported since 8-month-old

–

M

1 y, 8 m

6 m

Focal seizure

Head control (3 m), sit alone (6 m), walk (1 y, 4 m)

Normal

Normal EEG (6 m); Boundary condition (1 y, 6 m)

Normal (1 y, 6 m)

Controlled by OXC (30 mg/kg/d), no seizures reported since 18 m

–