RPS 211 - Spine and nerves

Purpose:

To investigate possible brain reorganisation after spinal cord injury (SCI) using multimodal fMRI and to further study their association with clinical variables.

Methods and materials:

21 traumatic SCI patients and 21 healthy controls (HCs) were recruited. The 3D whole-brain structural and resting-state functional images were acquired from all participants using a 3.0 Tesla MRI system. VBM and TBSS analysis were conducted to investigate the differences in brain structure between SCI patients and HCs, separately. Seed-based FC analysis was performed to explore the whole-brain functional changes using the results of brain structure as seeds. The association between brain changes and clinical variables was performed.

Results:

SCI patients showed GMV decrease in the dorsal anterior cingulate cortex (dACC), bilateral anterior insular cortex (aIC), bilateral orbital frontal cortex (OFC), and right superior temporal gyrus (STG). No significant difference in WM was found. When the seeds were located in the left aIC and right STG, SCI patients showed decreased FC in the bilateral primary sensorimotor cortex and left inferior parietal lobule (IPL), separately. Additionally, the FC value in the right primary sensorimotor cortex was positively correlated with the total motor score, while the FC value in the left IPL was positively correlated with the left/right/total motor score in SCI patients.

Conclusion:

These findings indicate that SCI can cause brain reorganisation in some higher cognitive areas, which are not related to sensorimotor function directly. More importantly, reorganisation of these regions may be vital factors in sensorimotor dysfunction through the decreased FC with sensorimotor areas after SCI.

Limitations:

We did not conduct a longitudinal study.

Ethics committee approval

The study protocol was approved by the ethics committee of our hospital.

Funding:

National Natural Science Foundation of China (No.81871339).

Purpose:

International guidelines state that patients with suspected cauda equina syndrome (CES) should undergo urgent lumbar MRI, ideally before referral to specialist spinal surgery units. This work, part of the evaluation of national treatment and investigation of cauda equina (ENTICE) study, aims to characterise the implications on patient care and for the receiving units of referrals with an incomplete investigation in this setting.

Methods and materials:

A retrospective, multicentre observational study of the investigation and management of patients with suspected CES was conducted across the UK, including all patients referred to a spinal unit from 1st October 2016-31st March 2017.

Results:

From a total of 4,441 referrals to 28 UK spinal units, more than half were made without any previous imaging and less than a fifth resulted in surgical decompression. In patients with incomplete initial studies, there was a statistically significant increase in time from presentation to MRI (median 13.9 vs 3.1 hours, p<0.001), but no significant increase in time from presentation to decompression. Approximately 85% of patients transferred for MRI were discharged without surgical intervention. Strict adherence to existing guidelines over this period would have resulted in a reduction of referrals and transfers by over 70%.

Conclusion:

For the majority of cases, an adequate investigation was not completed prior to a referral to specialist centres. Previous studies suggest that the costs associated with an incomplete investigation before referral clearly outweigh those of providing access to MRI scanning 24/7 in smaller hospitals. More studies, from countries with different levels of MRI availability and/or other systems of patient referral, are needed to understand the clinical magnitude of this problem and to establish transversally applicable guidelines.

Limitations:

A retrospective study with little information on long-term clinical outcomes.

Ethics committee approval

n/a

Funding:

No funding was received for this work.

Purpose:

To provide reference T2 values for magnetic resonance neurography (MRN) of the distal sciatic nerve and compare these to T2 changes in patients with nerve compression.

Methods and materials:

22 subjects (28.3±3.5 years) and 5 patients with unilateral sciatica due to degenerative disc disease with disc herniation underwent MRN using a T2-prepared turbo spin-echo (TSE) sequence of the distal sciatic nerve bilaterally. 5 and 2 healthy subjects further underwent a commonly used multi-echo spin-echo (MESE) sequence and magnetic resonance spectroscopy (MRS) as the gold-standard method, respectively. Measurements of T2 values were performed by two readers.

Results:

T2 values based on the T2-prepared TSE sequence were 44.4±3.0 ms (left) and 44.5±2.7 ms (right; p>0.05) in the healthy subjects and showed good inter-reader reliability. In patients, distal sciatic nerves showed T2 values of 61.5±6.2 ms (side of nerve affection) vs 43.3±2.4 ms (unaffected side). T2 values of MRS were in good agreement with measurements from the T2-prepared TSE sequence. However, they were not in agreement with those of the MESE sequence, which showed clearly higher values (62.8±3.2 ms [left] and 62.7±2.8 ms [right]).

Conclusion:

A T2-prepared TSE sequence enables the determination of accurate T2 values of the distal sciatic nerve, whereas a commonly used MESE sequence tends to overestimate nerve T2. Our approach may enable to quantitatively assess direct nerve affection in patients with nerve compression.

Limitations:

The small size of the patient cohort, but it is only intended to form a first case series for comparison to reference values.

Ethics committee approval

This prospective study was approved by the IRB.

Funding:

ERC and Philips Healthcare.

Purpose:

To evaluate the sensitivity of T2-mapping and the apparent diffusion coefficient in the determination of an early stage of intervertebral disc degeneration.

Methods and materials:

60 patients (mean age of 47.50±7.88) and 20 volunteers presenting with low-back pain underwent T2-mapping and DWI. All the lumber discs were evaluated morphologically and given a grade according to Pfirrmann's grading (I to IV). Every disc was divided into three parts: central, peripheral, and all-disc. The values of both T2 and ADC were calculated and analysis. The different correlation between the result and age were done using a ROC curve for both T2-mapping and ADC value, aiming to determine the cut-off values.

Results:

There was a negative correlation between T2 values and semi-quantitative grading (Pfirrmann grading) of disc degeneration and T2 values were significantly different when comparing grade I to V. A T2 value of nucleus pulposus was more sensitive than annulus fibrosus and the entire disc. ADC values were found to decrease with the increased degree of disc degeneration. There was a weakly significant negative correlation between age and T2-mapping values, ADC values of nucleus pulposus, and the entire disc.

Conclusion:

T2-mapping was significantly different when comparing grade I to V while ADC value had a significant weak negative correlation with age. T2-mapping and, to a smaller extent, ADC can be used for quantitative analysis of early disc degeneration for early diagnosis and better management.

Limitations:

The absence of histological correlation with the results, absence of direct relation between the morphological changes of disks and T2-mapping and DWI, and the subjective grading of disks by Pfirrmann grading.

Ethics committee approval

The study was approved by the ethical committee of Tanta University Hospital.

Funding:

No funding was received for this work.

Purpose:

To assess the MRI modifications of the intervertebral disc (IVD) treated by chemodiscolysis using T2-mapping sequences and possible associations with clinical and instrumental outcomes.

Methods and materials:

37 sciatica patients (20 males, 17 females; mean age 46.15 years) were enrolled for percutaneous CT-guided O2-O3 chemodiscolysis treatment. As a control group, we enrolled 28 patients treated by CT-guided periradicular injections. All patients were submitted to clinical (using visual analogue scale and Oswestry disability index) and imaging studies to evaluate the intervertebral disc area (IDA) and T2-mapping values of the IVD before, at 1-month, and 6-months follow-up.

Results:

The mean pre-treatment T2 relaxation time values were 38.80±4.51ms, 44.05±0.91ms, and 45.45±14.11ms for anterior annulus fibrosus (aAF), nucleus pulposus (NP), and posterior annulus fibrosus (pAF), respectively, with a significant increase at the level of the NP (p<0.05) at the 1-month follow-up. The 6-months follow-up showed a reduction with normalisation of intradiscal T2-mapping values. The mean ODI and VAS scores showed significant improvement at the post-treatment follow-up (p<0.05). Correlation analysis of T2 relaxation time values showed a significant correlation of NP values with both the reduction of IDA (0.81, p<0.001) and the improvement of clinical scores (0.86, p<0.001). In the control group, despite the clinical improvement, we did not find significant IVA reduction nor significant T2 values changes after treatment.

Conclusion:

T2-mapping may be a useful indicator to predict disc shrinkage and the clinical response to CT-guided O2-O3 injection.

Limitations:

The relatively small patient sample.

Ethics committee approval

All procedures were in accordance with the ethical standards of the institutional and/or national research committee and with the Helsinki declaration.

Funding:

No funding was received for this work.

Purpose:

The hypothesis is the relevance of sciatic nerve stiffness in follow-up patients with deep gluteal syndrome (DGS) who underwent surgery. Neurological examinations, pelvic MRI, and electromyography (EMG) were performed. Our focus was to follow-up sciatic nerve characteristics in patients after surgery compared with data one year later.

Methods and materials:

The sciatic nerve was scanned by strain elastography using ARFI (colour elastogram and stiffness ratio-SR), during knee movements in patients with DGS without surgery (89) and in patients (24) before and after surgery (follow-up 3 months) and one year later in 21 patients.

Results:

The evidently based recovery of sciatic nerve diameter (4.9 to 8 mm, in extension, and 3.9 to 4.6 mm, in flexion) and stiffness (7.3 to 1.3SR in extension, 3.9 to 4.6SR in flexion) shortly after surgery (p<0.01) was partially annulled (6.8 mm, 3.2SR, in extension, 4.4 mm, 6.7SR, in flexion) one year later (p<0.05). Sciatic nerve recovery after surgery was marked (r=0.881) relative to one year later (r=0.579). The correlation between MRI and EMG findings and ARFI nerve stiffness values in patients scheduled for surgery was high (r=0.963) and in those one year later (r=0.749). The overall specificity of the method was 83.8%, sensitivity was 78.4%, and accuracy of 83.9%. Compression processes and the accrual of nerve fibrous strips were evident (MRI) in some patients one year later.

Conclusion:

Elastography was a useful tool in decision-making for surgery and in the follow-up.

Limitations:

The study has to be developed with more observed cases, but limitations depend on surgical procedures and MRI findings.

Ethics committee approval

n/a

Funding:

No funding was received for this work.

Purpose:

All children with achondroplasia have craniocervical junction (CCJ) stenosis, which may lead to cardio-respiratory arrest. There is an on-going debate as to whether routine MRI screening is indicated in infants. Our aim was to assess MR findings in a cohort of children with achondroplasia.

Methods and materials:

The severity of stenosis was assessed independently by 2 observers in the following way: 1=narrowing of CCJ, 2=complete effacement of CSF, 3=distortion and compression of the spinal cord, and 4=T2 changes in the cord. MR findings, MR assessment of CSF flow, polysomnography results, and history of surgical decompression were recorded. Interobserver reliability was assessed using Cohen’s kappa.

Results:

A total of 85 children under the care of our institution were identified. 52 patients underwent MRI. 7 were excluded due to insufficient pre-decompression imaging.

Lumbar stenosis was demonstrated in 13 of the 36 patients for whom whole-spine imaging was available. The median age for children with distal stenosis was 12 years, compared to 1 year for children without. Interobserver reliability of the scoring was 0.60 (moderate), which improved to 0.81 (strong) when grades 1 and 2 were merged.

Conclusion:

The distortion of the spinal cord at the CCJ (grades 3 and 4) correlates well with abnormal polysomnography. The presence of CSF flow does not exclude stenosis. In older children, we advocate acquiring whole-spine imaging due to the high prevalence of distal stenosis. To improve observer reliability, a 3 rather than 4-point MRI scoring system should be considered, merging the current grades 1 and 2.

Limitations:

This work is a single-centre retrospective analysis. The grading system has not been validated.

Ethics committee approval

n/a

Funding:

No funding was received for this work.

Purpose:

Hirayama’s disease (HD) is a benign, self-limited, motor neuron disease that results in sporadic juvenile muscular atrophy of the distal upper extremities. The aim is to analyse diffusion tensor imaging (DTI) parameters of HD which helps in earlier diagnosis and predicts the microarchitectural damage of the spinal cord and to assess the DTI parameters in both neutral and flexion positions of patients with HD and compare that with normal sex and age-matched controls. The diagnosis will be confirmed based on clinical, electromyographic, MRI findings, and follow-up.

Methods and materials:

This is a prospective study conducted in Barnard Institute of Radiology, MMC, and RGGGH. Consecutive subjects undergoing routine clinical spinal magnetic resonance for Hirayama Disease were invited to participate in this study. RESOLVE (readout segmentation of long variable echo trains ) DTI was performed using a 1.5T scanner (Avato, Siemens) and FA, ADC (MD), E1 (AD), E2, E3, and RD values were analysed.

Results:

9 patients with HD had decreased FA and increased ADC values in the neutral position compared to age and sex-matched controls, among whom 8 patients had further decreased FA and increased ADC in the flexion position. 1 patient with HD had FA and ADC values similar to the controls.

Conclusion:

DTI parameters confirm the damage of the cervical cord during flexion and non-invasively reveal the neural status of HD patients. FA and ADC is a useful micro-biomarker in diagnosing Hirayama disease.

Limitations:

Further studies with larger cohorts are needed to infer a definite conclusion. Observer bias while marking the region of interest.

Ethics committee approval

The study in approved by Institutional Ethical Committee of Madras Medical College.

Funding:

No funding was received for this work.