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AVMs/dAVFs can mimic demyelinating disease like NMO, ADEM, or transverse myelitis.
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Symptoms of vascular malformation can be worsened if treated with steroids.
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In atypical demyelinating disease, our cases back angiography to preclude AVMs/dAVFs.
Vascular malformations of the spinal cord and brainstem include dural arteriovenous fistulas (dAVF), arteriovenous malformations (AVM), and neoplastic lesions such as hemangioblastomas, and cavernous malformations (
). The most common type of spinal vascular malformation is dAVF that typically arises in the thoracolumbar region. This most commonly presents in males between 40 and 60 years old with progressive myelopathy (
). Spinal AVM's are less common than dAVFs. Spinal AVMs differ from dAVFs by the presence of a nidus of abnormal blood vessels. AVMs can be extradural, intradural, or intramedullary. Here, we discuss three cases of vascular malformations (two dAVFs and one AVM) presenting as an acute brainstem event, acute myelopathy, and recurrent myelopathy.
Case #1: A 72-year-old woman with past medical history of hyperlipidemia, hypertension, and rheumatic fever presented with sudden onset of right-sided weakness, dysarthria, diplopia, and ataxia. Brain MRI revealed abnormal signal intensity in the medulla with patchy contrast-enhancement and diffuse swelling. She was diagnosed with a subacute brainstem infarction and discharged to a rehabilitation facility, where she clinically improved over the period of three months.
Sixteen months later she returned with two months’ duration of progressive bilateral upper extremity numbness and weakness. Her neurological examination findings included limited extra-ocular movements in all gaze directions, left ptosis, 4/5 strength in all extremities, and diminished reflexes. Brain MRI revealed resolution of the abnormal signal intensity in the brainstem and punctuate foci of T2-hyperintensity in deep cerebral white matter. Cervical spine MRI revealed abnormal FLAIR signal intensity extending from the cervicomedullary junction to C7, with heterogeneous cord enhancement from C3–C7. Visual evoked potentials indicated prolonged conduction over the right prechiasmatic pathways. CSF was unremarkable and oligoclonal bands were absent. Subsequent pulse doses of intravenous methylprednisolone, azathioprine, and mycophenolate mofetil were tried for presumed neuromyelitis optica but discontinued due to worsening or adverse effects. She completed a five-day steroid treatment with gradual improvement and was discharged again to a rehabilitation facility.
Symptoms progressed, and follow-up MRI showed persistent enhancement. Conventional angiography showed early filling of intradural, perimedullary veins at C1. She underwent a right sub occipital craniotomy with the visualization of a C1-2 large arterial vessel exiting from the right C1 neural foramen with accompanying nerve root. Intraoperatively, this appeared to feed an abnormal venous plexus along the ventrolateral aspect of the right brainstem.
Case #2: A 63-year-old woman with past medical history of hypertension, gastroesophageal reflux, and anxiety was evaluated for severe headache, neck pain, nausea, and vomiting. Initial neurological examination was normal. CT of the brain showed no structural abnormality and lumbar puncture was normal with the exception of elevated protein (60 mg/dL). She had a daughter with multiple sclerosis. She was discharged, but remained symptomatic over the period of three days.
Upon return presentation, brain MRI demonstrated two ovoid, enhancing lesions in the brainstem. C-spine MRI demonstrated three abnormal T2 lesions. Two lesions were in the brainstem: there was a 6 mm focus of high T2 signal within the left paramedian pons and the previously visualized high T2 signal in the left half of the medulla. Both of these lesions enhanced with gadolinium, and there was also slight expansion of the medulla. MRI of the thoracic spine was normal. There was no restricted diffusion or susceptibility artifact.
A lumbar puncture showed a protein of 75 mg/dL with no inflammatory cells or oligoclonal bands. CSF studies were also negative for lyme, cryptococcal antigens, cytomegalovirus PCR, and angiotensin converting enzyme. Acute disseminated encephalomyelitis (ADEM) was the leading differential consideration and the patient was treated with intravenous methylprednisolone.
The patient's clinical examination deteriorated on steroids. She developed urinary retention, bilateral lower extremity weakness, and bilateral finger numbness. Review of the brain MRI raised concern for prominent flow voids surrounding the cervicomedullary junction. Conventional angiography demonstrated a 5 mm cerebellar pial AVM supplied by a branch of the left posterior inferior cerebellar artery (PICA). The venous drainage of the AVM was through a markedly dilated cerebellar vein. The pial AVM underwent endovascular embolization, and her symptoms began to resolve.
Case #3: A 55-year-old man presented with nine months of progressive difficulty with ambulation, bilateral leg pain, and bladder hesitancy. He had no history of trauma. His examination revealed 4/5 weakness in his legs and hyper-reflexia with ankle clonus bilaterally. MRI showed abnormal increased T2 signal intensity and swelling of the lower thoracic spine and multiple dilated intradural veins suggestive of arteriovenous fistula. A thoracic myelogram and follow-up MRI with contrast did not reveal an arterial feeder or AVM. CSF showed 3 nucleated cells and protein of 84 mg/dL. The diagnosis was incomplete transverse myelitis and the patient was discharged with an oral steroid taper.
The following month, he returned with continued progression of his symptoms. A spinal angiogram revealed no evidence of dAVF or AVM. Due to persistent worsening symptoms and the MRI evidence of dilated intramural veins, a second angiogram was performed of the left internal iliac artery, which demonstrated multiple feeders to a dural AV fistula at S1.
He underwent an L4 to S1 laminectomy and surgical repair of the dAVF. In the center of the thecal sac, a large central vein was noted intraoperatively with as many as three feeding vessels. Postoperatively, he had persistent lower extremity weakness and pain, requiring the use of intrathecal analgesia and years later, a spinal cord stimulator.
Discussion: These cases illustrate the difficulty in diagnosing vascular malformations of the spinal cord and brainstem. All three cases were first thought to represent variable forms of demyelinating disease: neuromyelitis optica, acute disseminated encephalomyelitis, and transverse myelitis. Initial laboratory and radiological data were misleading and delayed the diagnosis.
The clinical course of dAVF is usually one of a progressive myelopathy due to chronic hypoxia from decreased drainage in spinal veins, venous congestion, hypertension, and direct compression by enlarging veins – a venous congestion myelopathy (VCM). The initial symptoms of dAVF are gait disturbance, numbness, and paresthesia. However, due to delay in diagnosis, the most common symptoms are micturition or incontinence, leg weakness, in addition to numbness in the legs or buttocks (
). Many of these symptoms were noted in our three cases.
Some of these MRI abnormalities, such as T2 hyperintensity and variable gadolinium enhancement may mimic demyelinating disease, but there is no specific combination of clinical symptoms and signs, or radiographic and laboratory data that is typical of vascular malformation. It is important to consider vascular malformations in cases that do not fit with established criteria for other better defined disorders.
Case #3 illustrates the importance of a high clinical suspicion based on age and presentation with the need to repeat angiography of all levels of the spine if clinically indicated following evaluation - as has been reported (
). This could be emphasized as often as the diagnosis of AVM or AVF is ruled out prematurely based on inadequate imaging. Two of our cases demonstrated a worsening of neurological symptoms from dAVF or AVMs after steroid use. Previous authors have described reversible aggravation of neurological deficits after steroids in VCM patients. A potential mechanism for this worsening is from steroids leading to reduced retrograde perfusion in long standing venous hypertension (
Reversible aggravation of neurological deficits after steroid medication in patients with venous congestive myelopathy caused by spinal arteriovenous malformation.
). Exercise has also been described as aggravating symptoms of VCM, possibly from the same physiologic mechanism.
Treatment options for dAVF include surgical occlusion or endovascular embolization. Although disease progression can be halted, motor symptoms may not be improved and an even fewer proportion of patients will show sensory improvement. Our cases demonstrate the need for consideration of angiography to improve outcomes in patients with atypical presentation and persistent or variable MRI findings with enhancement.
Case #1: Gadolinium enhanced T1 sagittal MRI showing superficial enhancement of the upper cervical spinal cord. B) Case #1: anterior-posterior view digital subtraction angiogram in the arterial phase showing the vertebro-basilar junction and AVM at the C1 level. C) Case #2: gadolinium enhanced T1 axial MRI showing patchy medullary enhancement. D) Case #2: sagittal view digital subtraction angiogram in the arterial phase showing the posterior arterial circulation and a cerebellar pial AVM. E) Case #3: T2 sagittal MRI showing abnormal signal throughout the thoracic spine. F) Case #3: anterior-posterior view digital subtraction angiogram in the arterial phase showing the left internal iliac artery and dAVF at the S1 level.
Reversible aggravation of neurological deficits after steroid medication in patients with venous congestive myelopathy caused by spinal arteriovenous malformation.
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