Radiation myelopathy: significance of gadolinium-DTPA enhancement in the diagnosis

Metabolic and Toxic Myelopathies

OBJECTIVE

This article reviews the clinical presentation, diagnostic evaluation, and treatment of metabolic and toxic myelopathies resulting from nutritional deficiencies, environmental and dietary toxins, drugs of abuse, systemic medical illnesses, and oncologic treatments.

LATEST DEVELOPMENTS

Increased use of bariatric surgery for obesity has led to higher incidences of deficiencies in nutrients such as vitamin B12 and copper, which can cause subacute combined degeneration. Myelopathies secondary to dietary toxins including konzo and lathyrism are likely to become more prevalent in the setting of climate change leading to drought and flooding. Although modern advances in radiation therapy techniques have reduced the incidence of radiation myelopathy, patients with cancer are living longer due to improved treatments and may require reirradiation that can increase the risk of this condition. Immune checkpoint inhibitors are increasingly used for the treatment of cancer and are associated with a wide variety of immune-mediated neurologic syndromes including myelitis.

ESSENTIAL POINTS

Metabolic and toxic causes should be considered in the diagnosis of myelopathy in patients with particular clinical syndromes, risk factors, and neuroimaging findings. Some of these conditions may be reversible if identified and treated early, requiring careful history, examination, and laboratory and radiologic evaluation for prompt diagnosis.

Risk of Myelopathy Following Second Local Treatment after Initial Irradiation of Spine Metastasis

Metastatic lesions of the spine occur in up to 40% of cancer patients and are a frequent source of pain and neurologic deficit due to cord compression. Palliative radiotherapy is the main first-intent local treatment in the form of single-fraction radiotherapy or fractionated courses. Reirradiation is a viable option for inoperable patients where spinal decompression is needed but with an increased risk of radiation-induced myelopathy (RM) and subsequent neurologic damage. This review summarizes reported data on local treatment options after initial irradiation in patients with relapsed spine metastasis and key dosimetric correlations between the risk of spinal cord injury and reirradiation technique, total dose, and time between treatments. The Linear Quadratic (LQ) model was used to convert all the published doses into biologically effective doses and normalize them to EQD2. For 3D radiotherapy, authors used cumulative doses from 55.2 Gy2/2 to 65.5 Gy2/2 EQD2 with no cases of RM mentioned. We found little evidence of RM after SBRT in the papers that met our criteria of inclusion, usually at the median reported dose to critical neural tissue around 93.5 Gy2/2. There is a lack of consistency in reporting the spinal cord dose, which leads to difficulty in pooling data.

T2* dynamic contrast enhanced MR perfusion for cervical cord lesions; does it work?

Background

The goal of this work was to assess the value of magnetic resonance (MR) perfusion in narrowing the differential diagnosis of cord lesions.

Thirty eight patients with different cervical cord lesions were involved in this study. This includes 20 males and 18 females, ranging between 13 and 60 years old.

Conventional MR with T2W (axial and sagittal) and pre and post contrast T1W (axial and sagittal) in addition to the T2* MR perfusion sequence were done. The final diagnosis of cervical cord tumors was achieved by biopsy and histopathological diagnosis, while inflammatory lesions were proved by clinical, laboratory data and follow-up for six months.

Results

Neoplastic lesions were found in 13 patients, while 25 patients had inflammatory lesions. Relative cord/cerebral blood volume (rCBV) was significantly higher in neoplastic lesions when compared to non-neoplastic ones (2 ± 1.13 vs 1.01 ± 0.62), respectively. A cutoff value of 1.38 or higher has high sensitivity of 78% and specificity of 83% in differentiating between these lesions.

Conclusion

T2* is a valuable technique in differentiating neoplastic from non-neoplastic cervical cord lesions.

Radiation-Induced Myelitis: Initial and Follow-Up MRI and Clinical Features in Patients at a Single Tertiary Care Institution during 20 Years

Myelitis is a rare complication of radiation exposure to the spinal cord and is often a diagnosis of exclusion. A retrospective review of clinical records and serial imaging was performed to identify subjects with documented myelitis and a history of prior radiation. Eleven patients fulfilled the inclusion criteria. All patients had longitudinally extensive cord involvement with homogeneous precontrast T1 hyperintense signal in the adjacent vertebrae, corresponding to the radiation field. T2 signal abnormalities involving the central two-thirds of the cord were seen in 6/11 patients (55%). The degree of cord expansion and contrast enhancement was variable but was seen in 6 (54%) and 5 (45%) patients, respectively. On follow-up, 2 patients developed cord atrophy, while complete resolution was noted in 1. Clinical improvement was noted in 5 patients, with symptom progression in 2 patients. Our results suggest that radiation myelitis is neither universally progressive nor permanent, and some radiographic and clinical improvement may occur.

Epidural and intramedullary spinal metastasis: clinical features and role of fractionated radiotherapy

Metastases involving the spinal epidural space and cord parenchyma are major sources of neurological impairment and decreased quality of life in cancer patients. Herein we review the clinical manifestations, pathophysiology, importance of early diagnosis and initiation of treatment, and role of fractionated radiotherapy of these disorders.

MRI in transverse myelitis

Transverse myelitis is an acute inflammatory disease of the spinal cord, characterized by rapid onset of bilateral neurological symptoms. Weakness, sensory disturbance, and autonomic dysfunction evolve over hours or days, most progressing to maximal clinical severity within 10 days of onset. At maximal clinical severity, half will have a paraparesis, and almost all patients have sensory disturbance and bladder dysfunction. Residual disability is divided equally between severe, moderate and minimal or none. The causes of transverse myelitis are diverse; etiologies implicated include demyelinating conditions, collagen vascular disease, and parainfectious causes, however, despite extensive diagnostic work-up many cases are considered idiopathic. Due to heterogeneity in pathogenesis, and the similarity of its clinical presentation with those of various noninflammatory myelopathies, transverse myelitis has frequently been viewed as a diagnostic dilemma. However, as targeted therapies to optimize patient outcome develop, timely identification of the underlying etiology is becoming increasingly important. In this review, we describe the imaging and clinical features of idiopathic and disease-associated transverse myelitis and its major differentials, with discussion of how MR imaging features assist in the identification of various sub-types of transverse myelitis. We will also discuss the potential for advanced MR techniques to contribute to diagnosis and prognostication.

Response to MLN8237 in pancreatic cancer is not dependent on RalA phosphorylation

The high prevalence of KRAS mutations and importance of the RalGEF-Ral pathway downstream of activated K-ras in pancreatic ductal adenocarcinoma (PDAC) emphasize the importance of identifying novel methods by which to therapeutically target these pathways. It was recently demonstrated that phosphorylation of RalA S194 by Aurora A kinase (AAK) is critical for PDAC tumorigenesis. We sought to evaluate the AAK-selective inhibitor MLN8237 as a potential indirect anti-RalA-targeted therapy for PDAC. We used a site-specific phospho-S194 RalA antibody and determined that RalA S194 phosphorylation levels were elevated in a subset of PDAC cell lines and human tumors relative to unmatched normal controls. Effects of MLN8237 on anchorage-independent growth in PDAC cell lines and growth of patient-derived xenografts (PDX) were variable, with a subset of cell lines and PDX showing sensitivity. Surprisingly, RalA S194 phosphorylation levels in PDAC cell lines or PDX tumors did not correlate with MLN8237 responsiveness. However, we identified Ki67 as a possible early predictive biomarker for response to MLN8237 in PDAC. These results indicate that MLN8237 treatment may be effective for a subset of patients with PDAC independent of RalA S194 phosphorylation. Ki67 may be an effective pharmacodynamic biomarker to identify response early in the course of treatment.

Neuroimaging in acute transverse myelitis

Transverse myelitis is an acute inflammatory condition. A relatively rare condition, the diversity of causes makes it an important diagnostic challenge. An approach to the classification and work-up standardizes diagnostic criteria and terminology to facilitate clinical research, and forms a useful tool in the clinical work-up for patients at presentation. Its pathogenesis can be grouped into four categories. Imaging appearances can be nonspecific; however, the morphology of cord involvement, enhancement pattern, and presence of coexistent abnormalities on MR imaging can provide clues as to the causes. Neuroimaging is important in identifying subgroups that may benefit from specific treatment.

Diagnostic and therapeutic strategy for confounding radiation myelitis

We report a case of confounding radiation myelitis to demonstrate the usefulness of surgical biopsy in ensuring the correct diagnosis and to avoid unnecessary treatment. The patient was a 40-year-old man with a history of epiglottis carcinoma and sarcoidosis. Six months after radiation therapy and chemotherapy for epiglottis carcinoma, he noticed paresthesia and dysesthesia in the left arm and leg. Two months after that, he complained of severe neck pain and rapidly progressing weakness in all extremities. MRI showed an enhanced intramedullary lesion with extensive edema in the cervical spinal cord. Radiation myelitis, intramedullary spinal tumor, and neurosarcoidosis were considered as differential diagnoses. Spinal cord biopsy with laminectomy was performed and radiation myelitis was diagnosed. After the surgery, the lesion was significantly decreased in size even though corticosteroid therapy was rapidly tapered. We emphasize that a spinal cord biopsy is indicated to obtain a pathological diagnosis and to make a clear treatment strategy for patients with associated diseases causing lesions of the spinal cord.

La neuropathie motrice pure, une complication rare de la radiothérapie: trois observations et une revue de la littérature

BACKGROUND

Early or late neurological symptoms with lesions of peripheral or central nervous system can originated from radiotherapy.

METHODS

We report three cases of pure motor neuropathy in patients, which were treated by X-ray treatment several years ago.

RESULTS

Three patients (35-65 years old) have been presenting a pure motor neuropathy between 8.5 and 21 years after radiotherapy for Hodgkin disease (two cases) or testicular seminoma (one case). In each case, a proximodistal weakness with proximal predominance was observed and confirmed by the electromyographic findings. After a gradual worsening, we observed a clinical stability in patients treated by anticoagulant (one case) or pentoxifylline (two cases).

CONCLUSION

Pure motor neuropathy is a rare and late complication of the radiotherapy. A treatment with anticoagulant or pentoxifylline, with or without tocopherol, has been suggested.

Radiation myelopathy after radioactive iodine therapy for spine metastasis

A case of radiation myelopathy after radioactive iodine therapy is reported. This is the first report to describe radiation myelopathy after I-131 therapy. A 62-year-old female with spinal metastasis of T10 received I-131 therapy. She presented with radiation myelopathy 34 months after the irradiation. We need to recognize the possibility of this serious complication even in the case of I-131 therapy. There is a risk of radiation myelopathy even after I-131 therapy, especially in cases with spinal cord compression such as this.

Nervous system infections in patients with cancer

The diagnostic approach to the patient with cancer with suspected CNS infection depends on an analysis of the patient's immune defect, the time course of development of manifestations of infection, and the type of clinical syndrome with supportive evidence for a specific diagnosis coming from laboratory and neuroradiographic data. Most patients with CNS infections can be grouped into those with signs of meningitis or meningoencephalitis and those with focal mass lesions. A smaller group presents with stroke-like onset. Except for the group with strokes, those with focal deficits usually present in a more indolent fashion, whereas those with meningitis and encephalitis present more acutely [63]. Patients with B-lymphocyte dysfunction are susceptible to encapsulated bacterial pathogens. Patients with T-lymphocyte impairment develop CNS infections that are caused by intracellular pathogens, particularly viruses (HSV, JC, CMV, HHV-6), Nocardia, Aspergillus, and Toxoplasma. Many noninfectious entities, such as drug treatment complications, radiation effects, recurrent tumor, and paraneoplastic syndromes, can mimic CNS infections. Although cryptococcosis, bacterial meningitis, and some viral infections are easily diagnosed from Gram's stain, culture, or PCR, patients with mass lesions may require tissue biopsy to confirm diagnosis. Patients with cancer differ from normal hosts in the distribution of pathogens, and there is a wider range of differential diagnostic issues, both infectious and noninfectious, for the relatively few clinical syndromes that present as potential CNS infections.

Non-neoplastic intramedullary pathology. Diagnostic dilemma: to Bx or not to Bx

There are several non-neoplastic lesions which may mimic intramedullary spinal cord neoplasm in their radiographic and clinical presentation. These can be classified as either infectious (TB, fungal, bacterial, parasitic, syphilis, CMV, HSV) and non-infectious (sarcoid, MS, myelitis, ADEM, SLE) inflammatory lesions, idiopathic necrotizing myelopathy, unusual vascular lesions (amyloid, infarct, isolated intramedullary vascular lesions) and radiation myelopathy. Although biopsy may be indicated in many cases, the mistaken diagnosis of intramedullary neoplasm can often be eliminated pre-operatively.

Radiation myelopathy

Radiation myelitis has long been recognised as a sinister consequence of spinal irradiation and has limited the acceptable dose of therapeutic radiation to the cord. Over the past 10 years, the pathogenesis has been increasingly understood through the use of animal models. The importance of 'dose per fraction' and 'inter-fraction interval' have been incorporated into new mathematical models which suggest that, for small fractions, the cord may tolerate higher doses of radiation than was previously thought. Clinical recognition of the condition has improved through the description of characteristic magnetic resonance imaging changes. However little advance has been made in its treatment.

Radiation myelopathy: a clinicopathological study with special reference to correlation between MRI findings and neuropathology

We describe magnetic resonance imaging (MRI) and neuropathological findings in a patient with chronic progressive radiation myelopathy (CPRM). An 81-year-old man with esophageal cancer underwent radiotherapy. Four years later he developed a progressive neurological deficit below the irradiated level of the spinal cord. Neurological examination revealed spastic paraplegia. MRI findings showed an area of high signal intensity on T2-weighted images of the thoracic spinal cord. On the basis of clinical and MRI findings, we diagnosed his condition as CPRM. MRI performed thirteen months after onset of neurological signs revealed mild atrophy of the spinal cord detected on T1-weighted images and an area of high signal intensity within the spinal cord detected on T2-weighted images. Neuropathological examination revealed findings consistent with radiation myelopathy. We speculate that the area of high signal intensity within the spinal cord detected on T2-weighted images might be a result of proliferation of small vessels, which was discovered upon autopsy.

Serial MRI changes in radiation myelopathy

Using MRI we assessed the changes in signal, size, and contrast enhancement characteristics of the cervical spinal cord in radiation myelopathy developing after radiotherapy for nasopharyngeal carcinoma. We studied two men and five women, aged 40-77 years. The first MRI study was performed 1-4 months after the initial clinical manifestations of myelopathy, and follow-up MRI 2-22 months after the onset of symptoms. On the first study, all patients showed low signal intensity in a long segment of the cervical spinal cord on T1-weighted images, high signal on T2*-weighted images, and focal contrast enhancement at C1-2. In five patients there was also swelling of the spinal cord. The site of eccentric focal contrast enhancement correlated with the clinical manifestations. Follow-up imaging less than 10 months after the onset of symptoms showed no significant changes in signal intensity. Focal contrast enhancement at C1-2 remained the same in three patients, was more dense and larger in one, and less dense in another. Subsidence of swelling was seen in two patients. Atrophy of the spinal cord at C1-2, without abnormal signal and with faint contrast enhancement at C1-2 was revealed as early as 10 months after the onset of symptoms, but the contrast enhancement disappeared by 22 months. There was no correlation between clinical manifestations and spinal cord atrophy on MRI.

Radiation-induced myelopathy and vertebral necrosis

Radiation-induced myelopathy is often a diagnosis of exclusion. In addition to the classic criteria needed to support the diagnosis, the presence of another radiation-induced lesion, such as aseptic vertebral necrosis, is useful to confirm the cause of the spinal cord lesion.

[Late post-irradiation cervical spinal cord disease. A case]

A case of delayed progressive radiation myelitis (DPRM) which begin 11 months after naso pharyngeal carcinoma radiation, in a young man, is reported. The initial manifestation is often a Brown-Sequard's syndrome progressing to complete and permanent myelopathy, with notable absence of localized or radicular pain. The parenchymal change of the spinal cord in radiation myelopathy can be easily visualized with magnetic resonance imaging (MRI) however there may be cases in which MRI appearance alone does not distinguish specially between tumor and radiation necrosis with absolute confidence: therefore, DPRM is by necessity a diagnosis of exclusion, based on clinical, paraclinical results and course of disease. Corticosteroid therapy is accompanied by a significant remission of symptoms. The evolution is characterized by a worse prognosis, prevention is absolutely necessary based on perfect radiation technic, knowledge on tolerance of spinal cord to irradiation (time-dose-volume factors) and other risks factors (chemotherapy, age and vascular disease).

Significance of gadolinium-enhanced magnetic resonance imaging in differentiating spinal cord radiation myelopathy from tumor. Case report

A young woman with a fourth ventricular ependymoma underwent radiotherapy following tumor excision. Twenty months later she developed a progressive neurological deficit at the C-2 vertebral level. Gadolinium-enhanced magnetic resonance imaging, showed an intramedullary lesion at the C-2 level. Although radiation myelopathy was suspected, tumor recurrence could not be excluded. Re-exploration and histopathology both confirmed a diagnosis of radiation myelopathy. A retrospective review of the case indicated findings favoring radiation myelopathy. The pertinent literature is reviewed and the findings discussed.