Diffusion tensor imaging for degenerative cervical myelopathy

Diffusion tensor imaging for degenerative cervical myelopathy

Despite its invasiveness, computed tomography myelography (CTM) is still considered an important supplement to conventional magnetic resonance imaging (MRI) for preoperative evaluation of multilevel degenerative cervical myelopathy. Schöller et al., analyzed if diffusion tensor imaging (DTI) could be a less invasive alternative for this purpose.

In 20 patients with degenerative cervical myelopathy and an indication for decompression of at least one level, CTM was performed preoperatively to determine the extent of spinal canal/cerebrospinal fluid (CSF) space and cord compression (Naganawa score) for a decision on the number of levels to be decompressed. Fractional anisotropy (FA) and apparent diffusion coefficient (ADC) were correlated with these parameters and with MRI-based increased signal intensity (ISI). Receiver operating characteristic analysis was performed to determine the sensitivity to discriminate levels requiring decompression surgery. European Myelopathy Score(EMS) and neck/radicular visual analog scale (VAS-N/R) were used for clinical evaluation.

According to preoperative CTM, 20 levels of maximum and 16 levels of relevant additional stenosis were defined and decompressed. Preoperative FA and particularly ADC showed a significant correlation with the CTM Naganawa score but also with the ISI grade. Furthermore, both FA and ADC facilitated a good discrimination between stenotic and nonstenotic levels with cutoff values < 0.49 for FA and > 1.15 × 10-9 m2/s for ADC. FA and especially ADC revealed a considerably higher sensitivity (79% and 82%, respectively) in discriminating levels requiring decompression surgery compared with ISI (55%). EMS and VAS-N/R were significantly improved at 14 months compared with preoperative values.

DTI parameters are highly sensitive at distinguishing surgical from nonsurgical levels in CSM patients and might therefore represent a less invasive alternative to CTM for surgical planning 1).


A study population included 50 patients with symptoms of cervical myelopathy. The patients were evaluated based on symptoms using the European myelopathy scoring system and were divided into: Grade 1, including patients with mild symptoms; Grade 2, referring to patients with moderate symptoms and Grade 3, which included patients revealing severe symptoms. All the patients were investigated with a 1.5 T MRI unit acquiring DWI and DTI sequences. FA and ADC values from each spinal segment were analyzed in terms of Frequency, Percentage, Mean, Standard Deviation and Confidence Intervals. The comparison of values was done by ANOVA and post hoc analysis by bonferroni test. Comparison of accuracy of FA, ADC and T2WI in recognizing myelopathic changes was done by t-test. Receiver Operating Characteristics (ROC) analysis was performed to obtain a cut off value of FA and ADC for each spinal level to identify myelopathic change in the spinal cord.

The study revealed a significant difference in the mean FA and ADC value of stenotic and Non-stenotic segments. T2WI was highly significant (p = 0.000) in recognizing myelopathy changes in patients falling under Grade 2(moderate) and Grade 3(severe) according to European Myelopathy scoring system. Regarding patients under Grade 1 (mild) FA and ADC values showed significant difference compared to T2WI. The collective sensitivity in the identification of myelopathic changes was highest with FA (79%) as compared to ADC (71%) and T2WI (50%). ROC analysis was done to determine the cut off values of FA and ADC at each cervical spine segments. The proposed cut off, for FA and ADC at the level of C1-C2 is 0.68 and 0.92, C2-C3 is 0.65 and 1.03, C3-C4 is 0.63 and 1.01, C4-C5 0.61 and 0.98, At C5-C6 0.57 and 1.04, At C6-C7 0.56 and 0.96 respectively.

FA and ADC values enhance the efficacy and accuracy of MRI in the diagnosis of cervical spondylotic myelopathy. Hence diffusion tensor imaging can be used as a non-invasive modality to recognize spondylotic myelopathy changes even in the early stages, which can be helpful in deciding on appropriate timing of decompression surgery before the irreversible chronic changes set in 2).


A meta-analysis was conducted to assess alterations in measures of diffusion tensor imaging (DTI) in the patients of cervical spondylotic myelopathy (CSM), exploring the potential role of DTI as a diagnosis biomarker. A systematic search of all related studies written in English was conducted using PubMed, Web of Science, EMBASE, CINAHL, and Cochrane comparing CSM patients with healthy controls. Key details for each study regarding participants, imaging techniques, and results were extracted. DTI measurements, such as fractional anisotropy (FA), apparent diffusion coefficient (ADC), and mean diffusivity (MD) were pooled to calculate the effect size (ES) by fixed or random effects meta-analysis. 14 studies involving 479 CSM patients and 278 controls were identified. Meta-analysis of the most compressed levels (MCL) of CSM patients demonstrated that FA was significantly reduced (ES -1.52, 95% CI -1.87 to -1.16, P < 0.001) and ADC was significantly increased (ES 1.09, 95% CI 0.89 to 1.28, P < 0.001). In addition, a notable ES was found for lowered FA at C2-C3 for CSM vs. controls (ES -0.83, 95% CI -1.09 to -0.570, P < 0.001). Meta-regression analysis revealed that male ratio of CSM patients had a significant effect on reduction of FA at MCL (P = 0.03). The meta-analysis of DTI studies of CSM patients clearly demonstrated a significant FA reduction and ADC increase compared with healthy subjects. This result supports the use of DTI parameters in differentiating CSM patients from health subjects. Future researches are required to investigate the diagnosis performance of DTI in cervical spondylotic myelopathy 3).


The measurement of DTI indexes within the spinal cord provides a quantitative assessment of neural damage in various spinal cord pathologies. DTI studies in animal models of spinal cord injury indicate that DTI is a reliable imaging technique with important histological and functional correlates.

DTI is a noninvasive marker of microstructural change within the spinal cord. In human studies, spinal cord DTI shows definite changes in subjects with acute and chronic spinal cord injury, as well as cervical spondylotic myelopathy. Interestingly, changes in DTI indexes are visualized in regions of the cord, which appear normal on conventional magnetic resonance imaging and are remote from the site of cord compression. Spinal cord DTI provides data that can help us understand underlying microstructural changes within the cord and assist in prognostication and planning of therapies 4).

References

1)

Schöller K, Siller S, Brem C, Lutz J, Zausinger S. Diffusion Tensor Imaging for Surgical Planning in Patients with Cervical Spondylotic Myelopathy. J Neurol Surg A Cent Eur Neurosurg. 2019 Jun 10. doi: 10.1055/s-0039-1691822. [Epub ahead of print] PubMed PMID: 31181580.
2)

Nukala M, Abraham J, Khandige G, Shetty BK, Rao APA. Efficacy of diffusion tensor imaging in identification of degenerative cervical spondylotic myelopathy. Eur J Radiol Open. 2018 Dec 12;6:16-23. doi: 10.1016/j.ejro.2018.08.006. eCollection 2019. PubMed PMID: 30581892; PubMed Central PMCID: PMC6293016.
3)

Guan X, Fan G, Wu X, Gu G, Gu X, Zhang H, He S. Diffusion tensor imaging studies of cervical spondylotic myelopathy: a systemic review and meta-analysis. PLoS One. 2015 Feb 11;10(2):e0117707. doi: 10.1371/journal.pone.0117707. eCollection 2015. Review. PubMed PMID: 25671624; PubMed Central PMCID: PMC4363894.
4)

Vedantam A, Jirjis MB, Schmit BD, Wang MC, Ulmer JL, Kurpad SN. Diffusion tensor imaging of the spinal cord: insights from animal and human studies. Neurosurgery. 2014 Jan;74(1):1-8. doi: 10.1227/NEU.0000000000000171. PubMed PMID: 24064483.

Cervical spondylotic myelopathy surgery outcome

Cervical spondylotic myelopathy surgery outcome

see Machine learning for degenerative cervical myelopathy.

Whilst decompressive surgery can halt disease progression, existing spinal cord damage is often permanent, leaving patients with lifelong disability.

Early surgery improves the likelihood of recovery, yet the average time from onset of symptoms to correct diagnosis is over 2 years. The majority of delays occur initially, before and within primary care, mainly due to a lack of recognition. Symptom checkers are widely used by patients before medical consultation and can be useful for preliminary triage and diagnosis. Lack of recognition of Degenerative Cervical Myelopathy (DCM) by symptom checkers may contribute to the delay in diagnosis.

The impact of the changes in myelopathic signs following cervical decompression surgery and their relationship to functional outcome measures remains unclear.

Surgery is associated with a significant quality of life improvement. The intervention is cost effective and, from the perspective of the hospital payer, should be supported 1).

Surgical decompression for CSM is safe and results in improved functional status and quality of life in patients around the world, irrespective of differences in medical systems and socio-cultural determinants of health 2).

The successful management of CSM depends upon an early and accurate diagnosis, an objective assessment of impairment and disability, and an ability to predict outcome. In this field, quantitative measures are increasingly used by clinicians to grade functional and neurological status and to provide decision-making support 3).


In addition, objective assessment tools allow clinicians to quantify myelopathy severity, predict outcome, and evaluate surgical benefits by tracking improvements throughout follow-up 4) 5) 6).

Several outcome measures assess functional impairment and quality of life in patients with cervical myelopathy 7) 8) 9) 10) 11).

A validated “gold standard,” however, has not been established, preventing the development of quantitative guidelines for CSM management 12).

In this field, one of the most widely accepted tool for assessing functional status is the modified Japanese Orthopaedic Association scale (mJOA).

Some studies have found that resolution of T2 hyperintensity in subjects with CSM who undergo ventral decompressive surgery correlates with improved functional outcomes. Other studies have found little correlation with postoperative outcome 13) 14).

References

1)

Witiw CD, Tetreault LA, Smieliauskas F, Kopjar B, Massicotte EM, Fehlings MG. Surgery for degenerative cervical myelopathy: a patient centered quality of life and health economic evaluation. Spine J. 2016 Oct 25. pii: S1529-9430(16)31022-1. doi: 10.1016/j.spinee.2016.10.015. [Epub ahead of print] PubMed PMID: 27793760.
2)

Fehlings MG, Ibrahim A, Tetreault L, Albanese V, Alvarado M, Arnold P, Barbagallo G, Bartels R, Bolger C, Defino H, Kale S, Massicotte E, Moraes O, Scerrati M, Tan G, Tanaka M, Toyone T, Yukawa Y, Zhou Q, Zileli M, Kopjar B. A Global Perspective on the Outcomes of Surgical Decompression in Patients with Cervical Spondylotic Myelopathy: Results from the Prospective Multicenter AOSpine International Study on 479 patients. Spine (Phila Pa 1976). 2015 May 27. [Epub ahead of print] PubMed PMID: 26020847.
3) , 12)

Singh A, Tetreault L, Casey A, et al. A summary of assessment tools for patients suffering from cervical spondylotic myelopathy: a systematic review on validity, reliability, and responsiveness [published online ahead of print September 5, 2013]. Eur Spine J. doi:10.1007/s00586-013-2935-x.
4)

Laing RJ. Measuring outcome in neurosurgery. Br J Neurosurg 2000;14:181–4.
5)

Holly LT, Matz PG, Anderson PA, et al. Clinical prognostic indicators of surgical outcome in cervical spondylotic myelopathy. J Neurosurg Spine 2009;11:112–8.
6)

Kalsi-Ryan S, Singh A, Massicotte EM, et al. Ancillary outcome measures for assessment of individuals with cervical spondylotic myelopathy. Spine (Phila Pa 1976) 2013;38:S111–22.
7)

Singh A, Crockard HA. Quantitative assessment of cervical spondylotic myelopathy by a simple walking test. Lancet 1999;354:370–3.
8)

Nurick S. The natural history and the results of surgical treatment of the spinal cord disorder associated with cervical spondylosis. Brain 1972;95:101–8.
9)

Olindo S, Signate A, Richech A, et al. Quantitative assessment of hand disability by the nine-hole-peg test (9-HPT) in cervical spondylotic myelopathy. J Neurol Neurosurg Psychiatry 2008;79:965–7.
10)

Hosono N, Sakaura H, Mukai Y, et al. A simple performance test for quantifying the severity of cervical myelopathy [erratum in: J Bone Joint Surg Br 2008;90:1534]. J Bone Joint Surg Br 2008;90:1210–3.
11)

Casey AT, Bland JM, Crockard HA. Development of a functional scoring system for rheumatoid arthritis patients with cervical myelopathy. Ann Rheum Dis 1996;55:901–6.
13)

Sarkar S, Turel MK, Jacob KS, Chacko AG. The evolution of T2-weighted intramedullary signal changes following ventral decompressive surgery for cervical spondylotic myelopathy. J Neurosurg Spine. 2014;21(4):538-546.
14)

Vedantam A, Rajshekhar V. Change in morphology of intramedullary T2- weighted increased signal intensity after anterior decompressive surgery for cervical spondylotic myelopathy. Spine (Phila Pa 1976). 2014;39(18):1458-1462.

Update: Overshunting associated myelopathy

Overshunting associated myelopathy” is a rare complication of CSF diversion that should be familiar to physicians who routinely evaluate patients with intracranial shunts 1) 2).

Only 12 previous cases have been reported in the literature 3).

OSAM has to be considered according to the Monro-Kellie hypothesis and is affected by an engorgement of the cervical epidural venous plexus, which can produce cervical myelopathy. Since it can be treated simply by increasing the shunt resistance, surgeons should be aware of the rarely detected overdrainage complication 4).

Classically, patients present with positional headache, but less common symptoms include neck pain and cranial nerve palsies.


A 45-year-old-patient with shunt-dependent, congenital hydrocephalus presented with an 8-year history of progressive tetraparesis and gait disorder in the Department of Neurosurgery, University of Tübingen, Germany. The patient was wheelchair-dependent. A new MRI scan of the head revealed slit ventricle syndrome and dural enhancement due to shunt overdrainage. An MRI and a CT-Phlebography of the cervical spine revealed engorgement of the epidural venous plexus with secondary compression of the spinal cord and myelomalacia. Surgery was performed during which we implanted a shunt valve. The patient recovered from surgery without any new deficits. The tetraparesis improved during the inpatient hospital stay. CT-Phlebography was performed 5 days after surgery and showed that the epidural venous plexus anterior to the cervical spinal cord had returned to nearly normal size. On follow-up examination 3 month after surgery, the patient´s strength had improved, and he was able to walk short distances with assistance and with ankle foot orthosis on the right side.

OSAM has to be considered according to the Monro-Kellie doctrine and is affected by an engorgement of the epidural cervical venous plexus, which can produce cervical myelopathy. Since it can be treated simply by increasing the shunt resistance, surgeons should be aware of the rarely detected overdrainage complication 5).


Ho et al., presented 2 cases of cervical myelopathy produced by engorged vertebral veins due to overshunting. Overshunting-associated myelopathy is a rare complication of CSF shunting. Coexisting cervical degenerative disc disease may further increase the difficulty of diagnosing the condition. Neurosurgeons and others who routinely evaluate patients with intracranial shunts should be familiar with this rare but possible diagnosis 6).


A 26-year-old woman with shunt-dependent, congenital hydrocephalus, presented with rapidly progressive cervical myelopathy following ventriculoperitoneal shunt revision. Imaging revealed engorgement of the cervical epidural venous plexus and mass effect on the cervical spinal cord. “Over-shunting associated myelopathy” is a rare complication of CSF diversion that should be familiar to physicians who routinely evaluate patients with intracranial shunts 7).

1) , 7)

Howard BM, Sribnick EA, Dhall SS. Over-shunting associated myelopathy. J Clin Neurosci. 2014 Dec;21(12):2242-4. doi: 10.1016/j.jocn.2014.05.014. Epub 2014 Jul 25. PubMed PMID: 25070631.

2) , 6)

Ho JM, Law HY, Yuen SC, Yam KY. Overshunting-associated myelopathy: report of 2 cases. Neurosurg Focus. 2016 Sep;41(3):E16. doi: 10.3171/2016.7.FOCUS16179. PubMed PMID: 27581312.

3) , 4) , 5)

Adib SD, Hauser TK, Engel DC, Tatagiba M, Skardelly M, Ramina K. Over-shunting associated myelopathy (OSAM) in a patient with bilateral jugular vein occlusion. World Neurosurg. 2018 Jun 1. pii: S1878-8750(18)31129-X. doi: 10.1016/j.wneu.2018.05.175. [Epub ahead of print] PubMed PMID: 29864573.
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