Supplemental Data

TABLE 1. Questionnaire based on two major clinical patterns of NFLS

MAJOR PATTERNS

Have you ever experienced (or did anybody tell you) one of the following phenomena while sleeping?

DYSTONIC PATTERN:

/

Sudden and rapid contraction of upper or/and lower limbs reaching abnormal and fixed position. This contraction is very strong and invincible (it is against your will).

HYPERKINETIC PATTERN:

/

Sudden awakening with a frightened expression followed by violent and fast upper and/or lower limb movements such as kicking or pedalling. Movements are often associated with an attempt to grasp something (pillow, mattress, an arm, a leg) and rolling movements of the body.

MINOR CHARACTERISTICS

Onset age >12yrs / Did the episodes start after the age of twelve?
Aura / Do you have a visual, auditory or mental sensation before or during the onset of movements?

Stereotyped onset

/

Is the initial pattern of movements during these episodes always the same?

Stereotyped semeiology

/ Are all the episodes very similar or almost the same?
Structured vocalization / During the episodes do you utter complex sentences or speech?
Unstructured vocalisation / During the episodes, do you utter sounds or simple meaningless words?
Wandering / At the end or during these episodes have you ever wandered about?
Duration < 2 min / Do the episodes last less than two minutes?

Specific period of the night

/ Do the episodes occur in a specific period of the night? If yes when?
Recall on awakening / On awakening do you remember the episodes?
Increased frequency / Has the frequency of these episodes increased in the years following their onset?
Clustered episodes / Did you ever have a period, lasting at least a month, of nightly recurrence of seizures?
Tonic-clonic seizures / Have you ever experienced a convulsion during sleep?

TABLE 2 Clinical features of false positive and false negative cases

N (M/F) / Age / Diagnosis / Interview
Positivity for / Possible reason of positive or negative answer
FP / 5 (1/4)
Case 15 / F / 53 / RLS / HP + c) < 2 min / Pt refers several daily episodes she had for one year when aged 38 yrs. These episodes spontaneously disappeared
Case 50 / F / 19 / Sleepwalking / HP + c) < 2 min / Pt refers a single episode she had at 18 yrs of age different from her habitual sleepwalking
Case 22 / M / 23 / Sleepwalking / DP / Pt refers three episodes he had from 21 to 22 yrs of age different from his sleepwalking
Case 80 / F / 56 / OSAS / DP / Pt refers to episodes she had from 6 yrs of age to date with weekly frequency, occurring early in the morning
Case 69 / F / 64 / PLMS / HP / Pt refers to episodes that started at 53 yrs appearing occasionally when she falls asleep, lasting a few seconds
FN / 17 (11/5) / 23.5*
(13-75)
2 PA / Episodes are brief, detected only by VPSG and pts usually are unaware of them. The DP is not recognized in the clinical history.
4 DS / Pts complain of jerks rather than DP disclosed only by VPSG
4 HS / No explanation for these cases.
7 ENW / Pts give a negative answer to the question on HP pattern because the complex motor behaviour preceding deambulation is usually brief without full awareness. Therefore pts complain only of sleepwalking that is not considered a complex motor behaviour.

Table 2 Legend: FP: false positive; FN: false negative; M: male, F: female;*mean age; PA: paroxysmal arousal; HS: hyperkinetic seizures; DS: dystonic seizures (i.e. asymmetric tonic/dystonic seizures); ENW: epileptic nocturnal wandering; HP: hyperkinetic pattern; DP: dystonic pattern; c) Duration < 2 min