Aarne Ylinen

Persistent symptoms in mild to moderate traumatic brain injury associated with executive dysfunction

In order to improve detection of subtle cognitive dysfunction and to shed light on the etiology of persistent symptoms after mild-to-moderate traumatic brain injury (TBI), we employed an experimental executive reaction time (RT) test, standardized neuropsychological tests, and diffusion tensor imaging (DTI). The Executive RT-Test, an Executive Composite Score from standardized neuropsychological tests, and DTI-indices in the midbrain differentiated between patients with persistent symptoms from those fully recovered after mild-to-moderate TBI. We suggest that persistent symptoms in mild-to-moderate TBI may reflect disrupted fronto-striatal network involved in executive functioning, and the Executive RT-Test provides an objective and novel method to detect it.

Assessing the State of Chronic Spinal Cord Injury Using Diffusion Tensor Imaging

The aim of this study was to quantify the association between diffusion tensor imaging (DTI) parameters of the cervical spinal cord and neurological disability in patients with chronic traumatic spinal cord injury (SCI). A cervical spinal cord 3T magnetic resonance imaging (MRI) with DTI sequences was performed on 28 patients with chronic traumatic SCI and 40 healthy control subjects. DTI metrics, including fractional anisotropy (FA), apparent diffusion coefficient (ADC), axial diffusivity (AD), and radial diffusivity (RD), were calculated within the normal-appearing spinal cord area at levels C2 or C3. Clinical assessment of the patients was performed according to the International Standards for Neurological Classification of Spinal Cord Injury (ISNCSCI) and the motor subscale of the Functional Independence Measure (FIM). The FA values of the patients with SCI were significantly lower than those of healthy control subjects (p<0.000001). In contrast, the ADC and RD values of these patients were significantly higher than those of control subjects (ADC p<0.0001, RD p<0.00001). In patients with SCI, the FA values were positively correlated with the motor (pr=0.56, p<0.01) and sensory (pr=0.66, p<0.001) scores of ISNCSCI and with the motor subscale of FIM (pr=0.51, p<0.01). DTI revealed spinal cord pathology, which was undetectable using conventional MRI. DTI changes in regions that were remote from the site of primary injury were most likely the result of secondary degeneration of white matter tracts. Decreased FA values were correlated with poorer motor and sensory function, as well as a lack of independence in daily living. DTI is a promising quantitative and objective tool that may be used in the clinical assessment of patients with SCI.

The benefit of active drug trials is dependent on aetiology in refractory focal epilepsy

Background: Earlier studies have shown that aetiology makes a difference in the outcome of epilepsy, but there is a paucity of follow-up studies to evaluate the possibilities of achieving seizure freedom in initially refractory epilepsy. Methods: We evaluated the cause of epilepsy based on high-resolution brain MRI and patient history in 119 consecutive thoroughly examined adult patients with refractory focal epilepsy followed up in our centre. We also evaluated the influence of aetiology and duration of epilepsy in this patient cohort on the chances of achieving 12-month remission in a 2-year follow-up. Results: The major finding was that a substantial group of patients achieved remission; 30 (25%) initially refractory patients achieved at least 12 months remission during follow-up. A total of 40.0% of the patients with cryptogenic aetiology had achieved 12-month remission compared with the 16.2% patients with symptomatic aetiologies (age-adjusted OR 3.74, 95% CI 1.54 to 9.07, p = 0.004). Aetiologies often considered for surgical treatment (hippocampal sclerosis, cortical dysplasia, vascular malformation, tumour and dual pathology) carried an almost six-fold risk of persistent seizures compared with cryptogenic epilepsy (age-adjusted OR 5.85, 95% CI 2.00 to 17.11, p = 0.001). Conclusions: Patients with vascular malformation and dual pathology as aetiology were most refractory, none being in remission for 12 months. There were also patients achieving 12-month remission after a long period of active epilepsy. These results encourage physicians to continue with new drug trials, especially on patients with no possibilities of epilepsy surgery, as well as on those still having seizures after epilepsy surgery.

The use of F-response in defining interstimulus intervals appropriate for LTP-like plasticity induction in lower limb spinal paired associative stimulation.

BACKGROUND In spinal paired associative stimulation (PAS), orthodromic volleys are induced by transcranial magnetic stimulation (TMS) in upper motor neurons, and antidromic volleys by peripheral nerve stimulation (PNS) in lower motor neurons of human corticospinal tract. The volleys arriving synchronously to the corticomotoneuronal synapses induce spike time-dependent plasticity in the spinal cord. For clinical use of spinal PAS, it is important to develop protocols that reliably induce facilitation of corticospinal transmission. Due to variability in conductivity of neuronal tracts in neurological patients, it is beneficial to estimate interstimulus interval (ISI) between TMS and PNS on individual basis. Spinal root magnetic stimulation has previously been used for this purpose in spinal PAS targeting upper limbs. However, at lumbar level this method does not take into account the conduction time of spinal nerves of the cauda equina in the spinal canal. NEW METHOD For lower limbs spinal PAS, we propose estimating appropriate ISIs on the basis of F-response and motor-evoked potential (MEP) latencies. The use of navigation in TMS and ensuring correct PNS electrode placement with F-response recording enhances the precision of the method. RESULTS Our protocol induced 186±17% (mean±STE) MEP amplitude facilitation in healthy subjects, being effective in all subjects and nerves tested. COMPARISON WITH EXISTING METHOD We report for the first time the individual estimation of ISIs in spinal PAS for lower limbs. CONCLUSIONS Estimation of ISI on the basis of F and MEP latencies is sufficient to effectively enhance corticospinal transmission by lower limb spinal PAS in healthy subjects.

Long-term paired associative stimulation can restore voluntary control over paralyzed muscles in incomplete chronic spinal cord injury patients

Emerging therapeutic strategies for spinal cord injury aim at sparing or restoring at least part of the corticospinal tract at the acute stage. Hence, approaches that strengthen the weak connections that are spared or restored are crucial. Transient plastic changes in the human corticospinal tract can be induced through paired associative stimulation, a noninvasive technique in which transcranial magnetic brain stimulation is synchronized with electrical peripheral nerve stimulation. A single paired associative stimulation session can induce transient plasticity in spinal cord injury patients. It is not known whether paired associative stimulation can strengthen neuronal connections persistently and have therapeutic effects that are clinically relevant. We recruited two patients with motor-incomplete chronic (one para- and one tetraplegic) spinal cord injuries. The patients received paired associative stimulation for 20–24 weeks. The paraplegic patient, previously paralyzed below the knee level, regained plantarflexion and dorsiflexion of the ankles of both legs. The tetraplegic patient regained grasping ability. The newly acquired voluntary movements could be performed by the patients in the absence of stimulation and for at least 1 month after the last stimulation session. In this unblinded proof-of-principle demonstration in two subjects, long-term paired associative stimulation induced persistent and clinically relevant strengthening of neural connections and restored voluntary movement in previously paralyzed muscles. Further study is needed to confirm whether long-term paired associative stimulation can be used in rehabilitation after spinal cord injury by itself and, possibly, in combination with other therapeutic strategies.

Necessity of monitoring after negative head CT in acute head injury.

OBJECTIVE The main objective of this study was to evaluate the incidence of delayed complications in acute head injury (HI) patients with an initial normal head computed tomography (CT). MATERIALS AND METHODS This retrospective study included 3023 consecutive patients who underwent head CT due to an acute HI at the Emergency Department (ED) of Tampere University Hospital (August 2010-July 2012). Regardless of clinical injury severity, the patients with a normal head CT were selected (n=2444, 80.9%). The medical records of these patients were reviewed to identify the individuals with a serious clinically significant complication related to the primary HI. The time window considered was the following 72h after the primary head CT. A repeated head CT in the hospital ward, death, or return to the ED were indicative of a possible complication. RESULTS The majority (n=1811, 74.1%) of the patients with a negative head CT were discharged home and 1.1% (n=27) of these patients returned to ED within 72h post-CT. A repeated head CT was performed on 12 (44.4%) of the returned patients and none of the scans revealed an acute lesion. Of the 632 (25.9%) CT-negative patients admitted to the hospital ward from the ED, a head CT was repeated in 46 (7.3%) patients within 72h as part of routine practice. In the repeated CT sample, only one (0.2%) patient had a traumatic intracranial lesion. This lesion did not need neurosurgical intervention. The overall complication rate was 0.04%. CONCLUSION In the present study, which includes head injuries of all severity, the probability of delayed life-threatening complications was negligible when the primary CT scan revealed no acute traumatic lesions.

Oral motor functions, speech and communication before a definitive diagnosis of amyotrophic lateral sclerosis.

The aim of this study was to explore the cranial nerve symptoms, speech disorders and communicative effectiveness of Finnish patients with diagnosed or possible amyotrophic lateral sclerosis (ALS) at their first assessment by a speech-language pathologist. The group studied consisted of 30 participants who had clinical signs of bulbar deterioration at the beginning of the study. They underwent a thorough clinical speech and communication examination. The cranial nerve symptoms and ability to communicate were compared in 14 participants with probable or definitive ALS and in 16 participants with suspected or possible ALS. The initial type of ALS was also assessed. More deterioration in soft palate function was found in participants with possible ALS than with diagnosed ALS. Likewise, a slower speech rate combined with more severe dysarthria was observed in possible ALS. In both groups, there was some deterioration in communicative effectiveness. In the possible ALS group the diagnostic delay was longer and speech therapy intervention actualized later. The participants with ALS showed multidimensional decline in communication at their first visit to the speech-language pathologist, but impairments and activity limitations were more severe in suspected or possible ALS. The majority of persons with bulbar-onset ALS in this study were in the latter diagnostic group. This suggests that they are more susceptible to delayed diagnosis and delayed speech therapy assessment. It is important to start speech therapy intervention during the diagnostic processes particularly if the person already shows bulbar symptoms.

Identification of alcohol abuse and transition from long-term unemployment to disability pension

Aims: The aim of the study was to reveal potential gaps and inconsistencies in the identification of alcohol abuse in health care and in employment services and to analyse the granting of disability pensions with respect to the alcohol abuse identification pattern. Methods: The material consisted of documentary information on 505 long-term unemployed subjects with low employability sent to the development project entitled ‘Eligibility for a Disability Pension’ in 2001–2006 in Finland. The dichotomous variables ‘Alcohol abuse identified in employment services’ and ‘Alcohol abuse identified in health care’ were cross-tabulated to obtain a four-class variable ‘Alcohol abuse identification pattern’. Logistic regression analyses were conducted to ascertain the association of alcohol abuse identification pattern with the granting of disability pensions. Results: Alcohol abuse was detected by both health care and employment services in 47% of those identified as abusers (41% of examinees). Each service systems also identified cases that the other did not. When alcohol abuse was identified in health care only, the OR for a disability pension being granted was 2.8 (95% CI 1.5–5.2) compared with applicants without identified alcohol abuse. The result remained the same and statistically significant after adjusting for confounders. Conclusions: Alcohol abuse identified in health care was positively associated with the granting of a disability pension. Closer co-operation between employment services and health care could help to identify those long-term unemployed individuals with impaired work ability in need of thorough medical examination.

Identification of Depression and Screening for Work Disabilities among Long-Term Unemployed People

The study explores whether clinical screening targeted at work disabilities among long-term unemployed people reveals eligible individuals for a disability pension and the importance of depression in granting the disability pensions. A total of 364 participants of the screening project were considered as eligible to apply for disability pension. Among them, 188 were diagnosed as clinically depressed. They were classified into those with earlier depression diagnosis (n = 85), those whose depression had not been diagnosed earlier (n = 103), and those without diagnosed depression (n = 176). The association of this ‘Depression identification pattern’ with being granted a disability pension was explored by logistic regression analyses. Compared to those with earlier diagnosis, those whose depression had not been diagnosed earlier were granted disability pension more commonly (72% vs. 54% OR 2.2, p = 0.012). Corresponding figures of the undepressed were 73%, OR 2.3, p = 0.002. The adjustments did not affect the results. Clinical examination of the long-term unemployed people in terms of work disability seems to be worthwhile. In particular, the examination reveals new depression diagnoses, which contribute more to the award of disability pension than depression diagnosed earlier by regular health care. Novel ways to detect depression among the unemployed should be implemented in the health and employment services.

Image quality and signal distribution in 1.5-T and 3-T MRI in mild traumatic brain injury patients

Clear standards are lacking in the imaging modalities of the deficit in mild traumatic brain injury (MTBI) patients. The purpose of this study is to compare the image quality by signal distribution between 1.5 Tesla and 3 Tesla MRI in turbo spin echo (TSE) and gradient echo (GRE) images in normal hospital settings and to find preferences for which field to use in MTBI patients. We studied 40 MTBI patients with TSE and GRE; 20 patients were imaged at 1.5 T and 20 at 3 T. The imaging parameters were optimized separately for the two scanners. Histograms of the signal distribution in 22 ROIs were fitted to a 1-peak Gaussian model and the resulting peak positions were scaled in respect to the peak positions of genu of the corpus callosum and the caudate nuclei. Correlation of the contrast of the ROIs in reference to genu of the corpus callosum between both the two scanners and the two imaging sequences was good. Image contrast was similar at both in the TSE images; in the GRE images contrast improved from 1.5 T to 3 T. However, based on peak positions and widths, a slight drawback in the separability between the ROIs was observed when 1.5 T MRI was replaced by 3 T. No clear improvement in tissue contrast or separability of 3 T was found compared to 1.5 T. Imaging of MTBI with 3 T should therefore be based on other advantages of high-field imaging, such as improved SNR and spatial resolution.