Magnetoenkefalografian ja toiminnallisen magneettikuvauksen vertailu ja yhdistäminen tunto- ja liikejärjestelmän tutkimuksessa

MEG directly measures the neuronal events and has greater temporal resolution than fMRI, which has limited temporal resolution mainly due to the larger timescale of the hemodynamic response. On the other hand fMRI has advantages in spatial resolution, while the localization results with MEG can be ambiguous due to the non-uniqueness of the electromagnetic inverse problem. Thus, these methods could provide complementary information and could be used to create both spatially and temporally accurate models of brain function. We investigated the degree of overlap, revealed by the two imaging methods, in areas involved in sensory or motor processing in healthy subjects and neurosurgical patients. Furthermore, we used the spatial information from fMRI to construct a spatiotemporal model of the MEG data in order to investigate the sensorimotor system and to create a spatiotemporal model of its function. We compared the localization results from the MEG and fMRI with invasive electrophysiological cortical mapping. We used a recently introduced method, contextual clustering, for hypothesis testing of fMRI data and assessed the the effect of neighbourhood information use on the reproducibility of fMRI results. Using MEG, we identified the ipsilateral primary sensorimotor cortex (SMI) as a novel source area contributing to the somatosensory evoked fields (SEF) to median nerve stimulation. Using combined MEG and fMRI measurements we found that two separate areas in the lateral fissure may be the generators for the SEF responses from the secondary somatosensory cortex region. The two imaging methods indicated activation in corresponding locations. By using complementary information from MEG and fMRI we established a spatiotemporal model of somatosensory cortical processing. This spatiotemporal model of cerebral activity was in good agreement with results from several studies using invasive electrophysiological measurements and with anatomical studies in monkey and man concerning the connections between somatosensory areas. In neurosurgical patients, the MEG dipole model turned out to be more reliable than fMRI in the identification of the central sulcus. This was due to prominent activation in non-primary areas in fMRI, which in some cases led to erroneous or ambiguous localization of the central sulcus.Magnetoenkefalografia (MEG) mittaa suoraan aivojen hermosolujen sähköistä toimintaa ja sillä on parempi ajallinen erotuskyky kuin aivojen aktivaation aiheuttamia paikallisen verenkierron muutoksia kuvaava toiminnallinen magneettikuvaus (TMK). TMK:lla on toisaalta etuja paikannuksessa MEG:hen nähden ja MEG:llä saadut paikannustulokset ovat monikäsitteisiä. Nämä menetelmät voivat täydentää toisiaan ja yhdessä niillä voidaan saada tarkempi ajallinen ja paikallinen kuva aivojen toiminnasta. Käytimme näitä kahta menetelmää aivojen tunto- ja liikejärjestelmän toiminnan kuvantamisessa terveillä koehenkilöillä ja neurokirurgisilla potilailla. Tutkimme menetelmillä saatavan paikannustuloksen yhteneväisyyttä ja käytimme TMK:sta saatavaa paikannustietoa MEG:llä mitattujen aivojen magneetisten vasteiden mallinuksessa luoden mallin aivojen tuntojärjestelmän toiminnasta. Neurokirurgisilla potilailla vertasimme kuvantamismenetelmien tuloksia leikkauksenaikaiseen sähköiseen liikeaivokuoren paikannukseen. Tutkimuksessa testattiin ja sovellettin kehittämiämme uusia kuva-analyysimenetelmiä. MEG:llä ja TMK:lla havaitsimme viitteitä aktivaatiosta tuntoärsykkeen kanssa samanpuoleisella primäärillä tuntoaivokuorella. Tuloksemme viittaavat lisäksi siihen että aivojen lateraalisessa fissuurassa on ainakin kaksi erillistä lähdealuetta jotka tuottavat magneettisia tuntoherätevasteita. Mallimme aivojen toiminnasta tuntoarsykkeen käsittelyn aikana vastasi hyvin kirjallisuudessa raportoituja suoraan aivoista mitattuja eri alueiden aktivaatioaikoja. TMK-analyysimenetelmiä vertailtaessa todettiin kuva-alkion naapurustoinformaatiota käyttävien menetelmien tuottavan paremmin toistettavia tuloksia. Kehittämämme menetelmä rajasi tarkemmin aivojen aktivaatioalueen ja oli muita menetelmiä herkempi havaitsemaan heikkoja aktivaatioita. Paikannettaessa aivojen keskusuurretta leikkauksen suunnittelua ja riskien arviointia varten MEG tuotti luotettavamman tuloksen kuin TMK jossa osalla potilaista aktivaatiot muilla kuin primäärillä liikeaivokuorella olivat voimakkaimpia vaikeuttaen tulosten tulkintaa

A Case of Alpha-Pyrrolidinopentiophenone (Flakka)-Induced Ischemic Stroke

Alpha-pyrrolidinovalerophenone (alpha-PVP) is a designer drug, the mechanism of action of which resembles that of cocaine and amphetamine. New data about the side effects of alpha-PVP are emerging. We present a case report of an acute ischemic stroke following the recreational use of alpha-PVP. The ischemic lesions were located in the middle cerebral artery and deep watershed areas of the left cerebral hemisphere. Occupational therapy and physiotherapy were initiated, and the patient was discharged with only a mild right hemiparesis.Peer reviewe

Synteettiset kontrastit magneettikuvauksessa

Teema : Magneettikuvaus. English summaryPeer reviewe

Comparison of reconstruction and acquisition choices for quantitative T2* maps and synthetic contrasts

Aim and scope: A Gradient Echo Plural Contrast Imaging technique (GEPCI) is a post-processing method, which can be used to obtain quantitative T2* values and generate multiple synthetic contrasts from a single acquisition. However, scan duration and image reconstruction from k-space data present challenges in a clinical workflow. This study aimed at optimizing image reconstruction and acquisition duration to facilitate a post-processing method for synthetic image contrast creation in clinical settings. Materials and methods: This study consists of tests using the American College of Radiology (ACR) image quality phantom, two healthy volunteers, four mild traumatic brain injury patients and four small vessel disease patients. The measurements were carried out on a 3.0 T scanner with multiple echo times. Reconstruction from k-space data and DICOM data with two different coil-channel combination modes were investigated. Partial Fourier techniques were tested to optimize the scanning time. Conclusions: Sum of squares coil-channel combination produced artifacts in phase images, but images created with adaptive combination were artifact-free. The voxel-wise median signed difference of T2* between the vendor's adaptive channel combination and k-space reconstruction modes was 2.9 +/- 0.7 ms for white matter and 4.5 +/- 0.6 ms for gray matter. Relative white matter/gray matter contrast of all synthetic images and contrast-to-noise ratio of synthetic T1-weighted images were almost equal between reconstruction modes. Our results indicate that synthetic contrasts can be generated from the vendor's DICOM data with the adaptive combination mode without affecting the quantitative T2* values or white matter/gray matter contrast.Peer reviewe

Return to work after mild traumatic brain injury : association with positive CT and MRI findings

Background Return to work (RTW) might be delayed in patients with complicated mild traumatic brain injury (MTBI), i.e., MTBI patients with associated traumatic intracranial lesions. However, the effect of different types of lesions on RTW has not studied before. We investigated whether traumatic intracranial lesions detected by CT and MRI are associated with return to work and post-concussion symptoms in patients with MTBI. Methods We prospectively followed up 113 adult patients with MTBI that underwent a brain MRI within 3-17 days after injury. Return to work was assessed with one-day accuracy up to one year after injury. Rivermead Post-Concussion Symptoms Questionnaire (RPQ) and Glasgow Outcome Scale Extended (GOS-E) were conducted one month after injury. A Kaplan-Meier log-rank analysis was performed to analyze the differences in RTW. Results Full RTW-% one year after injury was 98%. There were 38 patients with complicated MTBI, who had delayed median RTW compared to uncomplicated MTBI group (17 vs. 6 days), and more post-concussion symptoms (median RPQ 12.0 vs. 6.5). Further, RTW was more delayed in patients with multiple types of traumatic intracranial lesions visible in MRI (31 days, n = 19) and when lesions were detected in the primary CT (31 days, n = 24). There were no significant differences in GOS-E. Conclusions The imaging results that were most clearly associated with delayed RTW were positive primary CT and multiple types of lesions in MRI. RTW-% of patients with MTBI was excellent and a single intracranial lesion does not seem to be a predictive factor of disability to work.Peer reviewe

Traumatic Microbleeds in Mild Traumatic Brain Injury Are Not Associated with Delayed Return to Work or Persisting Post-Concussion Symptoms

The main objective of this prospective cohort study was to evaluate whether traumatic microbleeds (TMBs) are a significant prognostic factor of return to work (RTW), post-traumatic symptoms, and overall recovery in patients with mild traumatic brain injury (mTBI). One hundred and thirteen patients with mTBI were recruited from the Helsinki University Hospital emergency units. All patients underwent multi-contrast 3T magnetic resonance imaging (MRI) 3-17 days after mTBI. Patients were evaluated in the Traumatic Brain Injury Outpatient Clinic of Helsinki University Hospital 1 month after injury. Post-concussion symptoms were assessed with the Post-Concussion Symptom Questionnaire (RPQ) and overall recovery was assessed with the Glasgow Outcome Scale Extended (GOS-E). Their time to RTW was continuously measured up to 1 year after TBI. Median RTW was 9 days (interquartile range [IQR] 4-30) after mTBI and full RTW rate after 1 year was 98%. Patients with TMBs (n = 22) did not have more post-concussion symptoms (median RPQ 10.0 vs. 7.0, p = 0.217) or worse overall recovery (58% vs. 56% with GOS-E = 8, p = 0.853) than patients without TMBs (n = 91). There was no significant difference in time to RTW (13.5 vs. 7.0 days, p = 0.063). In this study, patients with TMBs did not have delayed RTW or more post-concussion symptoms than other patients with mTBI. TMBs in mTBI do not seem to be a significant prognostic factor of RTW.Peer reviewe

Aivokasvainta sairastava potilas päivystyksessä

Vertaisarvioitu. Teema : aivokasvaimet. English summary.Glioomaa sairastava potilas joutuu sairautensa aikana todennäköisesti asioimaan useita kertoja erikoissairaanhoidon päivystyksessä. On tavallista, että diagnoosiin johtavat kuvantamistutkimuksetkin tehdään päivystysluonteisesti, tyypillisimmin potilaan ensimmäisen epileptisen kohtauksen vuoksi. Myös nopeasti etenevät neurologiset puutos- tai kognitiiviset oireet saattavat ylittää kynnyksen päivystysluonteisille tutkimuksille ja paljastaa taustalla olevan aivokasvaimen. Kuvantamisessa magneettikuvaus (MK) on keskeinen. Myös hoitojen tai myöhemmän seurannan aikana voi voinnin yllättävä heikkeneminen edellyttää päivystyksellistä arviointia. Vaikka syynä voi olla kasvaimen eteneminen, johtuvat ongelmat usein hoidon komplikaatioista. Leikkauksen jälkeisten murheiden lisäksi tavallisia ovat lääkehoidon komplikaatiot, epileptiset kohtaukset sekä sädehoidon jälkeinen niin sanottu pseudoprogressio. Hoitoratkaisut edellyttävät usein neurologin, onkologin ja neurokirurgin tiivistä yhteistyötä.Peer reviewe

Post-traumatic headache after mild traumatic brain injury in a one-year follow up study - risk factors and return to work

Background Post-traumatic headache (PTH) is a common symptom following mild traumatic brain injury (mTBI). Patients at risk to develop acute PTH (aPTH) and further persistent PTH (pPTH) need to be recognized. Methods This is a one-year follow-up of 127 patients with mTBI, aged 18 to 68, referred to outpatient clinic in the Helsinki University Hospital. Symptoms were assessed at the emergency department (ED), with structured interview at outpatient clinic visit and with Rivermead post-concussion symptom questionnaire at one, three, and 12 months after injury. Psychiatric disorders were assessed with Structured Clinical Interview for DSM-IV Axis I disorders at 3-4 months and return to work (RTW) from patient records. Results At one month, 77/127 patients (61%) had aPTH. According to multiple logistic regression analysis, risk factors for aPTH were headache at the emergency department (ED) (OR 5.43), other pain (OR 3.19), insomnia (OR 3.23), and vertigo (OR 5.98). At three months, 17 patients (22% of aPTH patients) had developed pPTH, and at one year, 4 patients (24% of pPTH patients) still presented with pPTH. Risk factors for pPTH at three months were older age (OR 1.06) and current insomnia (OR 12.3). The frequency of psychiatric disorders did not differ between the groups. pPTH patients performed worse on their RTW. Conclusions Risk factors for aPTH were insomnia, headache at ED, other pain, and vertigo and for pPTH, insomnia and older age. RTW rate was lower among pPTH patients.Peer reviewe

Prognosis after Mild Traumatic Brain Injury: Influence of Psychiatric Disorders

Background: We evaluated the prevalence of psychiatric disorders in mild traumatic brain injury (MTBI) patients and investigated psychiatric comorbidity in relation to subjective symptoms and return to work (RTW). Methods: We recruited 103 MTBI patients (mean age 40.8 years, SD 3.1) prospectively from University Hospital. The patients were followed up for one year. The Rivermead Post-Concussion Symptom Questionnaire (RPQ) and Extended Glasgow Outcome Scale (GOSE) were administered one month after MTBI. Three months after MTBI, any psychiatric disorders were assessed using the Structured Clinical Interview for DSM-IV Axis I Disorders. Results: Psychiatric disorders were diagnosed in 26 patients (25.2%). The most common disorders were previous/current depression. At three months, there was no difference between patients with psychiatric disorders versus those without them in RTW (95.7% vs. 87.3%, p = 0.260) or at least in part-time work (100% vs. 94.4%, p = 0.245). In Kaplan–Meier analysis, the median time to RTW was 10 days for both groups. The median RPQ score was 13.0 (Interquartile range (IQR) 6.5–19.0) in patients with a psychiatric disorder compared to 8.5 (IQR 2.3–14.0) in those without one (p = 0.021); respectively, the median GOSE was 7.0 (IQR 7.0–8.0) compared to 8.0 (IQR 7.0–8.0, p = 0.003). Conclusions: Approximately every fourth patient with MTBI had a psychiatric disorder. These patients reported more symptoms, and their functional outcome measured with GOSE at one month after MTBI was worse. However, presence of any psychiatric disorder did not affect RTW. Early contact and adequate follow-up are important when supporting the patient’s return to work