Johanna Pekkola

Attention to visual speech gestures enhances hemodynamic activity in the left planum temporale

Observing a speakers articulatory gestures can contribute considerably to auditory speech perception. At the level of neural events, seen articulatory gestures can modify auditory cortex responses to speech sounds and modulate auditory cortex activity also in the absence of heard speech. However, possible effects of attention on this modulation have remained unclear. To investigate the effect of attention on visual speech‐induced auditory cortex activity, we scanned 10 healthy volunteers with functional magnetic resonance imaging (fMRI) at 3 T during simultaneous presentation of visual speech gestures and moving geometrical forms, with the instruction to either focus on or ignore the seen articulations. Secondary auditory cortex areas in the bilateral posterior superior temporal gyrus and planum temporale were active both when the articulatory gestures were ignored and when they were attended to. However, attention to visual speech gestures enhanced activity in the left planum temporale compared to the situation when the subjects saw identical stimuli but engaged in a nonspeech motion discrimination task. These findings suggest that attention to visually perceived speech gestures modulates auditory cortex function and that this modulation takes place at a hierarchically relatively early processing level. Hum Brain Mapp, 2005.

Head and Neck Arteriovenous Malformations: Results of Ethanol Sclerotherapy

BACKGROUND AND PURPOSE: Peripheral AVM is a locally aggressive disease with a high tendency to recur; its treatment is complex, especially in the anatomically delicate head and neck area. Here, we report results of ethanol sclerotherapy for head and neck AVM and discuss its potential use for peripheral AVM. MATERIALS AND METHODS: We retrospectively assessed degree of AVM eradication, complications, and clinical or imaging signs of recurrence for 19 patients treated with ethanol sclerotherapy for head and neck AVM (1 intraosseous, 18 soft-tissue AVMs). RESULTS: Of the 19 patients, 11 had complete eradication of arteriovenous shunting at DSA, with 1 recurrence (mean follow-up 15 months), and for 7 patients, treatment is ongoing. During 59 treatment sessions, 12 patients experienced 14 complications, 1 leading to permanent functional damage. CONCLUSIONS: Ethanol sclerotherapy has potential for complete eradication of head and neck AVM with low recurrence within the first year after completion of treatment. Complete eradication may require several treatment sessions during which complications should be minimized with careful techniques.

Time window for recanalization in basilar artery occlusion: Speculative synthesis

Basilar artery occlusion (BAO) is one of the most devastating forms of stroke and few patients have good outcomes without recanalization. Most centers apply recanalization therapies for BAO up to 12–24 hours after symptom onset, which is a substantially longer time window than the 4.5 hours used in anterior circulation stroke. In this speculative synthesis, we discuss recent advances in BAO treatment in order to understand why and under which circumstances longer symptom duration might not necrotize the brainstem and turn therapeutic attempts futile. We raise the possibility that distinct features of the posterior circulation, e.g., highly developed, persistent collateral arterial network, reverse filling of the distal basilar artery, and delicate plasma flow siding the clot, might sustain brittle patency of brainstem perforators in the face of stepwise growth of the thrombus. Meanwhile, the tissue clock characterizing the rapid necrosis of a typical anterior circulation penumbra will not start. During this perilous time period, recanalization at any point would salvage the brainstem from eventual necrosis caused by imminent reinforcement and further building up of the clot.

Posterior fossa dural arteriovenous fistulas: diagnosis and follow-up with time-resolved imaging of contrast kinetics (TRICKS) at 1.5T

Background Time-of-flight MR angiography (TOF MRA) is currently the most widely used non-invasive imaging tool to diagnose dural arteriovenous fistula (DAVF). It is, however, not as sensitive as invasive digital subtraction angiography (DSA) for detecting the arteriovenous shunting inherent in DAVF. Dynamic contrast-enhanced MR angiography allows separation of arterial and venous phases of contrast passage though the brain and can thus demonstrate early venous filling through the arteriovenous shunt. Purpose To compare the diagnostic value of TOF MRA and a commercially available dynamic contrast-enhanced MR angiography sequence (TRICKS) at 1.5T in detecting posterior fossa DAVF. Material and Methods We retrospectively collected image data for 19 patients who underwent TOF MRA, TRICKS, and DSA either for primary diagnosis or for follow-up of posterior fossa DAVF and assessed the performance of TOF MRA and TRICKS in demonstrating the arteriovenous shunt, with DSA as the reference standard. Results TRICKS detected early arterial filling at 94.4% sensitivity and 83.3% specificity. TOF MRA detected high flow-related signal within venous structures at 64.7% sensitivity and 80% specificity. Conclusion The commercially available dynamic MR angiography sequence TRICKS with fully automatic vendor postprocessing at 1.5T is more sensitive than TOF MRA in detecting the arteriovenous shunt in posterior fossa DAVF.

The role of cortical beta oscillations in time estimation.

Estimation of time is central to perception, action, and cognition. Human functional magnetic resonance imaging (fMRI) and positron emission topography (PET) have revealed a positive correlation between the estimation of multi‐second temporal durations and neuronal activity in a circuit of sensory and motor areas, prefrontal and temporal cortices, basal ganglia, and cerebellum. The systems‐level mechanisms coordinating the collective neuronal activity in these areas have remained poorly understood. Synchronized oscillations regulate communication in neuronal networks and could hence serve such coordination, but their role in the estimation and maintenance of multi‐second time intervals has remained largely unknown. We used source‐reconstructed magnetoencephalography (MEG) to address the functional significance of local neuronal synchronization, as indexed by the amplitudes of cortical oscillations, in time‐estimation. MEG was acquired during a working memory (WM) task where the subjects first estimated and then memorized the durations, or in the contrast condition, the colors of dynamic visual stimuli. Time estimation was associated with stronger beta (β, 14 − 30 Hz) band oscillations than color estimation in sensory regions and attentional cortical structures that earlier have been associated with time processing. In addition, the encoding of duration information was associated with strengthened gamma‐ (γ, 30 − 120 Hz), and the retrieval and maintenance with alpha‐ (α, 8 − 14 Hz) band oscillations. These data suggest that β oscillations may provide a mechanism for estimating short temporal durations, while γ and α oscillations support their encoding, retrieval, and maintenance in memory. Hum Brain Mapp 37:3262–3281, 2016.

Comparison of CT and clinical findings of Terson's syndrome in 121 patients: a 1-year prospective study

OBJECT Tersons syndrome (TS) is a vitreous hemorrhage in association with subarachnoid hemorrhage (SAH). Its diagnosis is often delayed, which may result in vision loss secondary to treatable conditions. Methods to hasten early diagnosis and consequent ophthalmic referral are desirable. The aims of this study were 1) to assess the specificity and sensitivity of conventional head CT for diagnosing TS in patients with aneurysmal SAH (aSAH); and 2) to determine the incidence of TS and its association with age, sex, aSAH severity, and overall mortality. METHODS Patients admitted to Helsinki University Central Hospital who underwent surgery or endovascular treatment for a ruptured intracranial aneurysm during 2011 were participants in this prospective study. They underwent serial dilated fundoscopic examinations during a 6-month period. Two radiologists independently reviewed ocular findings suggestive of TS on conventional CT head scans obtained in all patients as a routine diagnostic procedure. Associations between TS and relevant clinical, radiological, and demographic data were analyzed with uni- and multivariate logistic regression. RESULTS Of 121 participants, 13 (11%) presented with TS, and another 22 (18%) with intraretinal hemorrhages. For reviewing CT head scans, the overall observed agreement between the 2 raters was 96% (116 of 121 cases), with a substantial κ of 0.69 (95% CI 0.56-0.82). The sensitivity of the CT findings for TS was 42%, and the specificity was 97%. Associations of the World Federation of Neurosurgical Societies (WFNS) and Hunt and Hess grades on admission, the presence of intracerebral hemorrhage, female sex, and aneurysm length with TS were all statistically significant. Logistic regression demonstrated that sex and WFNS grade were independently associated with TS and provided the best fit to the data. CONCLUSIONS Routinely looking for TS findings in CT head scans may prove valuable in clinical practice. Tersons syndrome is associated with female sex and poor clinical condition on admission.

Imaging of blood flow in cerebral arteries with dynamic helical computed tomography angiography (dhcta) using a 64-row CT scanner

Background: Cerebral computed tomography angiography (CTA) depicts a structural image of intracranial arteries without providing much time-resolved information on blood flow dynamics. Current CT technology allows obtaining of rapidly repeated helical scans during the arterial contrast filling phase after an intravenous contrast injection. Purpose: To report our experience on dynamic CT imaging in determining the direction of contrast filling within proximal intracranial arteries of operated cerebral artery aneurysm patients. Such dynamic information can help detect vascular occlusion or severe spasm. The method is here referred to as dynamic helical CT angiography (DHCTA). Material and Methods: We retrospectively collected image and related technical data for 23 patients who underwent DHCTA and CTA during their first postoperative day after cerebral artery aneurysm surgery. For DHCTA, we had helically scanned a 4-cm tissue volume three times in succession with a 64-row CT scanner at intervals of 2.6 s during arterial contrast filling after an intravenous contrast injection. We assessed how well DHCTA succeeded in demonstrating the direction of contrast filling in the proximal intracranial arteries, evaluated clinically relevant structural information provided by DHCTA and CTA, and compared radiation doses for the two methods. Results: For 21 patients, DHCTA outlined the direction of contrast filling in proximal intracranial arteries. As to arterial spasm and residual filling of the operated aneurysm, CTA and DHCTA gave similar information. Radiation doses were higher (P<0.000001) for DHCTA than for CTA at 120 kV tube voltage. At 100 kV, the difference was smaller, but doses for DHCTA still exceeded (P<0.05) those for CTA. Conclusion: DHCTA gave dynamic information unobtainable with CTA and could prove useful in selected clinical settings.

IV Thrombolysis-Bridging and Endovascular Treatment for Occlusive Internal Carotid Artery Dissection with Tandem Occlusion

Compared to other etiologies of ischemic stroke, occlusive internal carotid artery dissection responds worse to intravenous (IV) thrombolysis. Intracranial tandem occlusion is a predictor of poor outcome. A direct endovascular approach has been proposed as a safe and probably superior alternative to IV thrombolysis. However, it may lead to considerable treatment delays. We used rapidly initiated IV thrombolysis-bridging and subsequent endovascular treatment in two patients with severe hemispheric ischemia due to occlusive internal carotid artery dissection with tandem occlusion and achieved good outcomes. Minimizing recanalization times likely improves patient outcome and IV thrombolysis-bridging may be a reasonable strategy to achieve this. The positive initial results obtained with endovascular approaches and IV thrombolysis-bridging in this patient group deserve further scientific exploration.

Sclerotherapy complications of peripheral venous malformations

Background Sclerotherapy is often the primary treatment for peripheral venous malformations. It is mostly sufficient alone, but can be combined with other endovascular techniques. Despite its mini-invasiveness, it is not without potentially severe complications. Here, we systematically report sclerotherapy complications in trunk and extremity venous malformations. Methods We retrospectively assessed the complications of 127 consecutive patients who had received sclerotherapy for peripheral venous malformation in our tertiary care unit (January 2007–August 2013). We applied the Clavien–Dindo classification to grade the severity of complications. We mostly used detergent sclerosants (85.7%), and less often ethanol (5.7%) or bleomycin (4.2%). In 4.2% of the procedures, we combined glue, coils, endovascular laser or particles to sclerotherapy. Results The overall complication rate per procedure was 12.5%. Most complications (83.3%) were local and managed conservatively. We encountered four severe complications, all related to blood coagulopathy. Subcutaneous lesion location and use of ethanol significantly increased the risk of local complications. Conclusion Sclerotherapy alone or combined with other endovascular techniques is a safe method for local venous malformations with moderate risk for conservatively manageable complications. Blood coagulopathy constitutes a risk for, otherwise rare, severe complications.

Intravenous alteplase versus rescue endovascular procedure in patients with proximal middle cerebral artery occlusion

Objectives To compare outcome of ischaemic stroke patients undergoing rescue endovascular procedure for proximal middle cerebral artery occlusion with matched patients without endovascular procedure after unsuccessful intravenous thrombolysis. Methods Endovascularly treated patients with middle cerebral artery occlusion (n = 41) were matched by propensity score with similar patients treated by intravenous thrombolysis and having a considerable post-thrombolysis neurological deficit (n = 82). We compared their three-month outcome (modified Rankin Scale) and frequency of symptomatic intracerebral haemorrhage. For the endovascular group, we report onset-to-puncture time, onset-to-recanalization time, and recanalization rates. Results In age, gender, time from onset, admission National Institutes of Health Stroke Scale, systolic and diastolic blood pressure, blood glucose, history of hypertension, diabetes mellitus, hyperlipidaemia, atrial fibrillation, and congestive heart failure, and in aetiology, the groups were similar. Endovascular group patients had a recanalization rate of 90%, and more often reached three-month modified Rankin Scale 0–2 (36·6% vs. 18·3%, P = 0·03). Mortality was equally common (19·5%) in both groups, and frequency of symptomatic intracerebral haemorrhage was 9·8% vs. 14·6% (P = 0·45). The endovascular groups median onset-to-puncture time was four-hours and six-minutes and onset-to-recanalization time was five-hours and 12 min. The latter time was more than one-hour longer in patients treated under general anaesthesia compared with patients treated under conscious sedation (median four-hours 50 min vs. five-hours 58 min; P < 0·01). Conclusions Rescue endovascular approach increases likelihood of recanalization and may improve functional outcome in acute ischaemic stroke patients with proximal middle cerebral artery occlusion who did not respond to intravenous thrombolysis.