Role of Magnetic Resonance Imaging in the Evaluation of Compressive Myelopathy

Abstract

Background:

Compressive myelopathy is a common disease. Compressive myelopathy encompasses many pathological conditions that cause damage to the spinal cord or dysfunction of the spinal cord by compression either within the spinal cord or from the outside of the cord. Many of these spinal cord diseases have the potential to be reversible if recognised early and treated appropriately. Hence, the prognosis of this condition depends on a timely and accurate diagnosis. Magnetic resonance imaging (MRI) is essential when dealing with a multifactorial disorder, such as compressive myelopathy, which is considered one of the serious neurological emergencies. We attempted to evaluate the various causes of compressive myelopathy and to characterise them.

Materials and Methods:

This is a retrospective study conducted at a tertiary care hospital in Chennai from January 2024 to June 2024. We retrospectively examined a total of 48 cases from our department with the reports of compressive myelopathy on MRI spine studies.

Results:

We found that degenerative myelopathy (37.5%) was found to be the most common cause, followed by trauma (22.9%) and infection (18.8%), malignancy, including metastasis (16.7%), and Hirayama(4.2%). The cervical spine compression (54.2%) and the extradural compartment (89.6%) were more frequently involved.

Conclusion:

The study recommends MRI for individuals with suspected compressive myelopathy, as it accurately identifies the underlying cause and related characteristics. Providing precise information about the patient’s long-term prognosis is beneficial.

Introduction

Diseases causing cord compression can be classified into acute causes, such as traumatic causes, infection with abscess formation and chronic conditions like degenerative changes of the spine, tumoural compression of the cord and Hirayama.^[1] Magnetic resonance imaging (MRI) is the most accurate way to assess soft tissue damage, particularly in the spinal cord and ligaments. MRI can reveal fractured/subluxated vertebral bodies, causing stenosis of the spinal canal, and is also useful in assessing the posterior ligamentous injury. The signal abnormality inside the cord can be recognised and aid in determining the severity of trauma. MRI is an effective tool for imaging tumours affecting the spinal canal and spinal cord in cases of suspected cord compression caused by neoplasms. Early detection and treatment are crucial for reversing many spinal cord illnesses. Hence, the prognosis of this condition depends on a timely and accurate diagnosis.^[2] The purpose of MRI is to identify compressive from non-compressive myelopathy.

Materials and Methods

This is a retrospective study conducted in a tertiary care hospital in Chennai over six months, from January 2024 to June 2024. We have a total of 48 cases retrospectively searched in our department for reports of compressive myelopathy in MRI spine studies. The patients with clinical suspicious and imaging findings of compressive myelopathy at all age groups were included in this study. Patients with non-compressive causes of myelopathy like demyelination, ischaemia and with motion artefacts, metallic implants that rendered MRI technically infeasible were excluded from our study. The Institutional Ethics Committee accepted the study (Approval Number: AMH-C-S-063/07-24). Canal stenosis was classified according to the T2-weighted sagittal images into the following grades: grade 0, absence of canal stenosis; grade 1, subarachnoid space obliteration exceeding 50%; grade 2, spinal cord deformity; and grade 3, spinal cord signal change.^[3] MR classification system of intramedullary T2 hyperintensity signal intensity was divided into four categories, type 0 = normal signal intensity of spinal cord without any intramedullary T2 hyperintensity, type 1 = diffuse pattern of intramedullary T2 hyperintensity occupying more than two-thirds of axial dimension of spinal cord with an obscure and faint border, and types 2 and 3 = focal patterns of intramedullary T2 hyperintensity occupying less than two-thirds of axial dimension of spinal cord. Type 2 indicates focal intramedullary T2 hyperintensity with an obscure and faint border, whereas type 3 has a well-defined and distinct margin.^[4]

Study Protocol

All patients fulfilling the inclusion criteria were subjected to the study. MRI of the spine was performed on a 3.0-T (PHILIPS, INGENIA) using sixteen phased-array coils for the spine. The sequences were axial, sagittal section of T1- and T2-weighted scans, coronal section of short tau inversion recovery (STIR), and depending on clinical details, sagittal section of diffusion-weighted imaging (DWI) and apparent diffusion coefficient (ADC) will be done.

Statistical Analysis

Descriptive statistics were presented with frequency (percentage). Chi-square/Fisher’s exact test was used to determine the association between two independent categorical factors. P value < .05 is considered as statistical significance. All the statistical analysis was done by using SPSS (IBM, 28.0)

Results

The majority of cases were seen between the age group of 41 and 60 years (45.8%) [Table 1], with a male predominance of 40 patients (83.3%) [Table 1]. The most common cause of compressive myelopathy was degenerative disease seen in 18 patients (37.5%) followed by trauma seen in 11 patients (22.9%), infection with or without abscess formation seen in 9 patients (18.8%), malignancy including metastasis seen in 8 patients (16.7%) and Hirayama seen in 2 patients (4.2%) [Table 2].

Table 1.

Demographic factors

Parameters	(n = 48), n (%)
Age in years
≤20	4 (8.3)
21–40	10 (20.8)
41–60	22 (45.8)
>60	12 (25)
Gender
Male	40 (83.3)
Female	8 (16.7)

Extradural compression is most commonly seen in 43 patients (89.6%). Intradural extramedullary compression was seen in 5 patients (10.4%) [Table 2]. The cervical spine is most commonly involved in 26 patients (54.2%), followed by the thoracic spine seen in 11 patients (22.9%) and lumbar spine seen in 11 patients (22.9%) involvement [Table 2]. The association between the extradural and intradural extramedullary compartment lesion with the spinal cord compression at cervical, thoracic and lumbar regions was found to be significant with a P value of .004 [Table 6].

Table 2.

MRI profile of compressive myelopathy

Parameters	(n = 48), n (%)
MRI Diagnosis
Degenerative	18 (37.5)
Trauma	11 (22.9)
Infection	9 (18.8)
Malignancy including metastasis	8 (16.7)
Hirayama	2 (4.2)
Compartment Involvement
Extradural	43 (89.6)
Intradural extra medullary	5 (10.4)
Level of Spine Compression
Cervical	26 (54.2)
Thoracic	11 (22.9)
Lumbar	11 (22.9)

Degenerative

Causes of compressive myelopathy characterised by osteophytes and disc bulges were seen in 18 patients (100%), followed by disc protrusion seen in 7 patients (38.9%), and thickening of the posterior longitudinal ligament in 6 patients (33.3%) [Tables 3 and 4]. All of them show grade 3 canal stenosis, 13 patients showed type 1 T2 signal intensity and 3 individuals showed type 2 T2 signal intensity and rest of the remaining 2 show type 3 T2 signal intensity within the cord.

Table 3.

MRI characterisation of compressive myelopathy

Characterisation of Compressive Myelopathy	(n = 48), n(%)
Degenerative osteophytes	18 (37.5)
Disc bulge	18 (37.5)
Disc protrusion	7 (1.64)
Ligament hypertrophy	6 (12.5)
Trauma burst fracture	11 (22.9)
Posterior element fracture	8 (16.7)
Epidural haematoma	8 (16.7)
Ligament injury	4 (8.3)
Unstable fracture	4 (8.3)
Infection disc end-plate changes	9 (18.8)
Epidural collection	9 (18.8)
Pre- and paravertebral collection	9 (18.8)
Posterior element involvement	8 (16.7)

Table 4.

Disease-specific MRI features of compressive myelopathy

Disease-specific MRI Features of Compressive Myelopathy	Clinical Disease, n (%)
	Degenerative	Trauma	Infectious
Degenerative
Osteophytes	18 (100)	–	–
Disc bulge	18 (100)	–	–
Disc protrusion	7 (38.9)	–	–
Ligament hypertrophy	6 (33.3)	–	–
Trauma
Burst fracture	–	11 (100)	–
Posterior element fracture	–	8 (72.7)	–
Epidural haematoma	–	8 (72.7)	–
Ligament injury	–	4 (36.4)	–
Unstable fracture	–	4 (36.4)	–
Infection
Disc end-plate changes	–	–	9 (100)
Epidural collection	–	–	9 (100)
Pre- and paravertebral collection	–	–	9 (100
Posterior element involvement	–	–	8 (88.9)

Trauma

Causes of compressive myelopathy characterised by burst fractures seen in 11 patients (100%), posterior element fracture and epidural haematoma were seen in 8 patients (72.7%), followed by ligament injury and unstable fractures in 4 patients (36.4%) [Tables 3 and 4]. All of them show grade 3 canal stenosis, 8 patients showed type 1 T2 signal intensity and one individual shows type 2 T2 signal intensity and the rest of the 2 showed type 3 T2 signal intensity within the cord.

Infection

Causes of compressive myelopathy disc end-plate changes, epidural, pre- and paravertebral collection were seen in 9 patients (100%), and posterior elements involvement was seen in 8 patients (88.9%) [Tables 3 and 4]. All of them show grade 3 canal stenosis and type 1 T2 signal intensity changes within the cord.

Malignancy

Both primary and metastasis total of 8 cases. Five patients (62.5%) had intradural extramedullary components, and three patients (37.5%) had extradural components [Table 5]. All of them show grade 3 canal stenosis and type 1 T2 signal intensity changes within the cord.

Table 5.

Disease-specific MRI features of compressive myelopathy (malignancy)

Compartment	No. of Cases	%
Extradural	3	37.5
Intradural extramedullary	5	62.5
Total	8	100

The association between the extradural and intradural extramedullary compartment lesion with the spinal cord compression at cervical, thoracic and lumbar regions was found to be significant with a P value of .004 [Table 6]. In degenerative myelopathy and traumatic spinal injury, the cervical spine is most commonly involved. The most common region involved in infective spondylitis is the lumbar region

Table 6.

Association between cord compression and compartment involved

Compression	Compartment, n (%)		P Value*
	Extradural (n = 43)	Intradural Extramedullary (n = 5)
Cervical	26 (60.5)	–	.004
Thoracic	10 (23.3)	1 (20)
Lumbar	7 (16.3)	4 (80)

Discussion

Degenerative disc disease [Figure 1]: The most common cause of compressive myelopathy. These findings were similar to a study done by Choi et al.^[5] The intramedullary T2 high signal changes in cervical spondylosis are an indicator of poor prognosis, as this change is reflected as myelomalacia. The surgical outcomes were poorer in patients with intramedullary T2 hyperintense signal changes, especially when the signal changes in multiple segments. Thus, preoperative MRIs are used to predict postoperative recovery in degenerative cervical myelopathy.

Figure 1.

Note: T2 sagittal section of MRI cervical spine shows disc bulge with osteophytic complex and thickening of posterior longitudinal ligament compressing the cord from C3 to C6 level, causing reduction in calibre of cord with T2 hyperintense signal changes noted within the cord at C4-C5 level.

Traumatic myelopathy [Figure 2]: Of 11 cases of the cervical spine is the most commonly injured spine, which is concordant with Chen et al.^[6]

Figure 2.

Note: T2 and STIR sagittal section of MRI dorsal spine shows a burst fracture of D11 and D12 vertebra with retropulsion of the fracture fragment, causing severe spinal canal narrowing and cord compression. Involvement of the posterior element fracture and the posterior ligament complex is also seen.

Infective spondylodiscitis [Figure 3]: Of 9 cases of cord compression, pre- and paravertebral collections were associated with all the cases of infective spondylitis. This was similar to research done by Maurya et al.,^[7] who also concluded that MRI is the choice for imaging the spine, not only in diagnosing infective spondylitis but also in guiding surgical management. By vertebral biopsy and draining of cold abscess, the histopathology of all the cases was found to be of tuberculous origin. India bears a disproportionate share of the global TB burden, contributing approximately 26%–28% of all cases worldwide. Extrapulmonary TB, which includes spinal TB, accounts for about 3% of all TB cases. In skeletal TB, spinal involvement is the most common, comprising around 50% of all skeletal TB cases. The highest incidence is in the third and fourth decades of life. Males constituted approximately 64% of patients. Low socioeconomic status was a significant risk factor. The thoracic spine was most commonly affected.^[8]

Figure 3.

Note: STIR sagittal and T1 post-contrast axial images of MRI cervicodorsal spine show Gibbus deformity of D1 vertebra with heterogenous enhancement at C7 to D2 vertebral level. There is an epidural collection causing cord compression with associated pre- and paravertebral collection seen.

Spinal neoplasms [Figure 4]: Of the eight cases, seven cases were primary neoplasms, and one case was due to metastasis. Among them, five cases (62.5%) were in the intradural extramedullary compartment, and three (37.5%) cases were in the extradural compartment [Table 5]. After post-surgical excision of the lesion, the histopathology of the intradural tumour 3 was found to be schwannoma, and the other two were meningioma and neurofibroma. This was similar to research done by Mohanty et al.,^[9] which concluded that schwannoma was the most common intradural extramedullary tumour. However, the same study by Shim et al.^[8] showed intradural extramedullary tumours are common, which is concordant with our study. Histopathological examination of the extradural tumours revealed one case of metastasis and two cases of chondrosarcoma.

Figure 4.

Note: T2 sagittal and T1 post-contrast sagittal section of MRI cervicodorsal spine shows an epidural lesion with heterogenous enhancement at the D2 and D3 vertebrae level, causing posterior spinal cord compression.

Figure 5.

Hirayama T2 sagittal neutral and flexion sequence of MRI cervicodorsal spine shows anterior displacement of the posterior dura mater at the C4 to C7 level, compressing the spinal cord against the vertebral column. Focal cord atrophy changes are seen at the C5-C6 level.

Hirayama disease [Figure 5]: Of the 48 cases, two were due to accounting for 4% of cases. In both cases, flexion MRI imaging in these cases revealed a crescent-shaped altered signal intensity, which is T2 and STIR hyperintense, with few flow voids noted extending in the cervical spine, causing enlargement of the posterior epidural space. Hirayama disease is a rare condition characterised by asymmetric muscle weakness and atrophy. There is inordinate growth between the dural mater and the vertebral column, leading to a tight dural mater, which falls short in length compared to the vertebral column. This tight dural sac causes overstretching and compression of the cervical cord against the vertebral body on flexion movements. This also causes the compression of the anterior vertebral venous plexus. As a result, there will be engorgement of the posterior venous plexus in the spinal canal, leading to congestion. This further leads to ischaemia of the anterior horn cells.

Conclusion

MRI is the definitive modality for examining soft tissues of the spine and spinal cord abnormalities, including cord oedema/contusion and intervertebral discs and ligaments. Due to its high sensitivity, MRI is the preferred imaging method for detecting and characterising spinal tumours and infections. Finally, MRI is a highly definite, accurate, cost-effective, non-invasive, radiation-free method for evaluating compressive myelopathy.