Læknablaðið : fylgirit - 01.05.2002, Side 44

POSTERS / 3 3RD SNC & 2ND SCNN
Matcrial and ntetliods: Two experiments were carried out with ten
participants. In the first experiment the participants listened to 6
different sounds 200 ms in duration on a /ga-ka/ continuum. The
only difference between the sounds was that the VOT varied
between 10-60 ms. The sounds were presented through earphones.
Interstimulus interval was 1000 ms. The ERP elicited by the stimuli
was recorded from vertex. In the second experiment 6 disyllabic
words, 460 ms in duration on a /gala-kala/ continuum were used.
The beginning of these stimuli was exactly the same as in the first
experiment with the same variation in VOT. The ending /-la/ was
the same for all stimuli. The interstimulus interval was 2000 ms. The
ERP was recorded in the same way. Before the experiments
participants categorised the stimuli to ascertain that they heard the
difference.
Kcsults: In the first experiment sounds with longer VOT elicited
N100 with later onset than those with short VOT. In the second
experiment there was no correlation between N100 latency and
VOT.
Conclusion: The difference in outcome in the first and the second
experiment could possibly be due to the shorter interstimulus
interval in the first experiment. Another possibility is that in the
first experiment the N100 is elicited directly by meaningless stimuli
whereas in the second experiment the N100 is strongly influenced
by the cognitive content of the stimulus.
P19 - Prevalence of obstructive sleep apnea syndrome in
patients with difficult headache
Bekkelund Sl, Jensen R, Olsborg C, Torbergsen T, Salvesen R
Dept. of neurology, University Hospital of Tromso, Norway
Objective: Obstructive sleep apnea syndrome (OSAS) is a common
disorder in the general population. Although the mechanisms
remain obscure, an association with headache has been reported.
Most studies are cross-sectiona! in design with a limited number of
patients. We aimed to assess the prevalence of OSAS in a popu-
lation of patients with difficult headache referred to a neurological
specialist consultation.
Material and methods: We included all patients referred to neuro-
logical specialists for headache in Northern Norway during a period
of two years. Patients who reported heavy snoring and episodes of
breathing pauses at night underwent a polysomnographic (PSG)
examination. We regarded an apnea/hypopnea index of 5 or higher
as abnormal.
Results: Of 903 patients with difficult headache, 75 reported heavy
snoring and episodes of interrupted nocturnal breathing (8%).
Among 43 patients examined with PSG, 14 (1.5% of the total study
population) had an apnea/hypopnea index of 5 or higher. Eleven of
the patients reported headache at wake-up in the morning.
Conclusion: The prevalenGe of OSAS in a sample of patients
referred to specialist for difficult headache is not higher than what
is reporled for the general population. The relatively low preva-
lence of OSAS in this selected group of patients with difficult
headache does not support the notion that OSAS brings about
headache.
P20 - Do carpal canal stenosis predict outcome after surgical
treatment for carpal tunnel syndrome?
Bekkelund Si, Pierre-Jerome C
Dept. of neurology, University Hospital of TromsO, Norway
Objective: We investigated the role of carpal canal stenosis as a
predictor of outcome in patients who underwent surgical treatment
for carpal tunnel syndrome (CTS).
Material and methods: We performed magnetic resonance imaging
(MRI) of the wrist in 31 patients with clinically and neurophysio-
logically confirmed CTS. With a computerised analyser we quanti-
tatively calculated the focal narrowest point of the tunnel. Patient’s
assessment of CTS-related symptoms were obtained by using a
visual analogue scale before, and 6 months after treatment.
Results: Seventeen (56%) patients improved in all symptoms after
treatment. The focal narrowest point of the tunnel was identified at
its distal third in all patients, at 8 mm from the outlet. The median
area of the narrowest point in those who improved clinically (n=17)
was 238.9 mm2 compared with 269.8 mm2 in others (n=14), p=0.046.
Age and neurophysiological parameters were not associated with
positive outcome in this group.
Conclusion: Identification of carpal canal stenosis may be important
in selecting good candidates for treatment in symptomatic CTS.
P21 - Diagnostic disagreement in patients referred to a
neurological outpatient clinic
Albretsen C, Bekkelund Sl
Dept. of neurology, University Hospital of Tromsp, Norway
Objective: We aimed to study the diagnostic accuracy in patients
referred to a neurological specialist centre from general practice.
Material and methods: Patients consecutively referred from general
practice during 6 months were included in the study. The diagnoses
from general practitioners (GP) were recorded from the referral
letter while the final neurological diagnosis after specialist visit were
obtained from the specialist's notes.
Results: From a total of 1207 patients, 568 referred from primary
health care were examined by a neurologist for the first time. The
neurologists changed the diagnosis proposed by the general practi-
tioner (GP) in 281 patients (49%). After clinical examination, 186
(33%) had one or more neurological deficit. The neurologist initiated
some kind of treatment in 162 cases (29%). Among frequently
referred groups of patients, especially tension type headache and
mixed headache forms were underdiagnosed while the GP seemed to
overestimate cervical radiculopathia. We found a significant ten-
dency of diagnostic disagreement in those who had waited a longer
time for an appointment (p=0.05).
Conclusion: Improved diagnostic work-up in patients with less
serious conditions in primary practice may reduce the workload in
secondary neurological care and lliereby provide a better service for
those who need it.
P22 - Prevalence of head trauma in patients with difficult headache
Bekkelund Sl, Salvesen R
Dept. of neurology, University Hospital of Tromsp, Norway
Objective: To test whether chronic headache (>3 days/week) is more
prevalent than episodic headache (< 3 days/week) in patients with a
previous history of significant head trauma.
Material and Methods: We included 903 consecutive patients referred
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