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Klinicna slika motenj povrhje in globoke senzibilitete in hrbtenjacni izvabljeni potenciali
Avtor: Nina Pirc
Mentor: doc. dr. Borut Prestor, dr. med
Z novimi tehnikami registracije hrbtenjacnih izvabljenih potencialov (HIP) je mogoce natancno spremljati delovanje dolgih prog in internevronskih sistemov hrbtenjace med operacijami na hrbtenjaci. Opisani so posamezni elementi senzoricnih HIP (SHIP), ki imajo svoj izvor v dolocenih predelih hrbtenjace in jih je možno povezovati s klinicnimi nevrološkimi izpadi. Pri siringomielijah in intra- ter ekstramedularnih tumorjih so okvarjeni tocno doloceni predeli hrbtenjace, ki se kažejo v razlicnih stopnjah okvare povrhnje in globoke senzibilitete.
Namen raziskave je opredeliti povezavo med izpadi povrhnje (PS- dotik, bolecina, temperatura) in globoke (GS- vibracije, položaj sklepov) senzibilitete ter spremembo elementov prevodnih in internevronskih SHIP. Delovna hipoteza št.1 nam je bila, da se lastnosti elementov SHIP registriranih pri bolnikih z okvarami hrbtenjace, znacilno razlikujejo od SHIP registriranih pri populaciji brez okvare, hipoteza št. 2 pa, da obstaja povezava med izpadi povrhnje in globoke senzibilitete oz. okvaro dolocenih predelov hrbtenjace in spremembo elementov SHIP. Metoda temelji na registraciji SHIP z intraoperativnim nevromonitoringom, po draženju perifernih senzoricnih živcev, pri bolnikih operiranih na hrbtenjaci (bolecinski sindromi, tumorji, siringomielija). Bolnike smo razdelili na dve skupini (z in brez klinicnih znakov za okvaro hrbtenjace) in pri njih med operacijo registrirali prevodne in internevronske SHIP. Posamezni SHIP so sestavljeni iz razlicnih elementov, katerih spremembe so odraz okvare predela hrbtenjace, ki je njihov izvor.
Razlike med elementi, ki smo jih dobili med odzivi registriranimi pri bolnikih z klinicno okvaro in odzivi dobljenimi pri bolnikih brez klinicne okvare na hrbtenjaci, so bile dovolj velike (p>0,05), da so nam bolniki z motnjami v delovanju živcevja, služili kot testna skupina, drugi- brez motenj v delovanju živcevja pa kot kontrolna skupina. Za dokaz povezave med spremembami elementov SHIP in izpadi povrhnje in globoke senzibilitete, smo uporabili odzive, za katere smo z manj kot 5% tveganjem trdili da so patološki.
Najbolj sta bila, od registriranih elementov SHIP, spremenjena internevronski val N13 in kompleks valov NVV (nizko amplitudni visoko frekvencni valovi), kjer je povezava z izgubo povrhnje ali globoke senzibilitete ocitnejša. V primerih ko je bil N13 odsoten, je bila tudi izguba PS popolna, pri delno spremenjenem valu N13 pa je bil obcutek za povrhnjo senzibiliteto le zmanjšan. Podobna je najdba pri enostranski okvari hrbtenjacne sivine. Ob spremembi v trajanju NVV je bilo vecinoma najti spremenjeno zaznavanje v globoki senzibiliteti. Ta je bila okvarjena tudi v primerih spremenjenih prevodnih SHIP (predvsem PVP). Kadar so bili PVP ohranjeni PNP pa spremenjeni ali odsotni je bilo moc najti okvaro povrhnje senzibilitete.
[Abstract / English version]
Superficial and deep sensory disturbances and spinal somatosensory evoked potentials
Author: Nina Pirc
Mentor: doc. dr. Borut Prestor, dr. med
With new tehniques it is possibile to record spinal somatosensory evoked potentials (SSEP) and to evaluate their activities during operation. Specific elements of somatosensory evoked potentials (SEP) which have origo in certain parts of spinal cord, could be clinicaly connected to neurological defficite. Specific parts of spinal cord are damaged in syringomielia, intra- and extramedullar tumor. This can be seen as different grade of loss of pain, temperature, vibration and posture senses.
Aim of the study was to evaluate the connection between loss of superficial (pain & temperature) and deep (vibration & posture sense) sensations and change in segmental and conducted SEP. Working Hypothesis No.1 was that characteristics of SEP in patients with damage of spinal cord significant differ from those recorded with patients without spinal cord damage. Hypothesis No.2 was that there is a connection between loss of specific senses and change in characteristics of SEP.
Our method was based on intraoperative neuromonitoring of spinal cord after stimulation of peripheral nerves during operation procedure in patient with spinal pathology (syringomielija, inta-, extramedular tumor). Patients were divided in two groups (with and without clinical findings in neurological status). With each patient we recorded segmental and conducted SEP during surgical procedure. SEP consists of different elements and the changes of them reflect damage of part of the spinal cord, where they originate from.
The differences in elements, recorded with patients with and without clinical findings in neurological status, were significant enough (p<0.05). The patients with clinical findings in neurological status were used as a test group, and patients without clinical findings in neurological status as a control group. SEP, for which we could with less than 5% risk state that they are abnormal, were used as the proof of connection between changes in SEP elements and loss of superficial (pain & temperature) and deep (vibration & posture sense) sensations.
The most obvious were findings with segmental SEP wave N13 and LHW (low amplitude high frequency waves). In the cases of loss of N13, pain and temperature senses were absent. With partial loss, pain and temperature were only diminished. In cases of diminished duration of LHW, changes in vibration and posture senses were found. Diminished vibration and posture senses were also found in cases of distortion of conducted SEP (mostly with PVP changes). When PVP were preserved and PNP were lost or diminished, diminished pain and temperature senses were the main finding.