Perfusion imaging insights into SMART syndrome: a case report

Comprehensive Update and Review of Clinical and Imaging Features of SMART Syndrome

Stroke-like migraine attacks after radiation therapy (SMART) syndrome is a delayed complication of cranial irradiation, with subacute onset of stroke-like symptoms including seizures, visual disturbance, speech impairment, unilateral hemianopsia, facial droop, and aphasia, often associated with migraine-type headache. The diagnostic criteria were initially proposed in 2006. However, the diagnosis of SMART syndrome is challenging because clinical symptoms and imaging features of SMART syndrome are indeterminate and overlap with tumor recurrence and other neurologic diseases, which may result in inappropriate clinical management and unnecessary invasive diagnostic procedures. Recently, various imaging features and treatment recommendations for SMART syndrome have been reported. Radiologists and clinicians should be familiar with updates on clinical and imaging features of this delayed radiation complication because recognition of this entity can facilitate proper clinical work-up and management. This review provides current updates and a comprehensive overview of the clinical and imaging features of SMART syndrome.

SMART syndrome: a case report

INTRODUCTION

Stroke-like migraine attacks after radiation therapy (SMART) syndrome, is a late complication of brain radiotherapy (1). Symptoms are commonly subacute in onset and involve migraine type of headache, seizures, focal neurologic deficits (2). Magnetic resonance imaging (MRI) findings are usually unilateral and posterior predominant cortical-subcortical hyperintensity, swelling and prominent gyriform (cortical and leptomeningeal) gadolinium enhancement in the areas of the brain that underwent irradiation with or without diffusion restriction (1). There is no standard treatment protocol for SMART syndrome. Antiepileptics and corticosteroids are commonly used drugs.

CASE REPORT

A 65 years old woman was diagnosed with breast cancer with brain metastases and treated with more than 50 Gy brain radiotherapy. The patient presented with acute right-sided weakness and numbness, episodic myoclonic jerking of the right arm and leg, and gait instability five months later. MRI and magnetic resonance angiography of the brain with gadolinium revealed left parietooccipital cortical diffusion restriction and accompanying dilatation of the left posterior cerebral artery as new findings. Computed tomography (CT) perfusion revealed increased perfusion in the affected area. The patient was diagnosed with SMART syndrome.

MANAGEMENT AND OUTCOME

The patient was treated with dexamethasone (16 mg/day) and anticonvulsant therapy. Myoclonic seizures had almost completely remitted. However, her cognitive impairment persisted, then the patient was arrested because of aspiration a month later.

DISCUSSION

Besides confirming SMART syndrome, diagnostic investigations are also important to exclude other etiologies. Posterior reversible encephalopathy syndrome, post-ictal changes, meningoencephalitis, and cerebrovascular diseases are radiological differential diagnoses considered (3). Proper and early diagnosis of SMART syndrome is significant in preventing unnecessary aggressive approaches and appropriate treatment to avoid lesions of sequela.

Prognostic Factors of Stroke-Like Migraine Attacks after Radiation Therapy (SMART) Syndrome

BACKGROUND AND PURPOSE

Prognostic factors of stroke-like migraine attacks after radiation therapy (SMART) syndrome have not been fully explored. This study aimed to assess clinical and imaging features to predict the clinical outcome of SMART syndrome.

MATERIALS AND METHODS

We retrospectively reviewed the clinical manifestations and imaging findings of 20 patients with SMART syndrome (median age, 48 years; 5 women) from January 2016 to January 2020 at 4 medical centers. Patient demographics and MR imaging features at the time of diagnosis were reviewed. This cohort was divided into 2 groups based on the degree of clinical improvement (completely versus incompletely recovered). The numeric and categoric variables were compared as appropriate.

RESULTS

There were statistically significant differences between the completely recovered group (n = 11; median age, 44 years; 2 women) and the incompletely recovered group (n = 9; median age, 55 years; 3 women) in age, months of follow-up, and the presence of steroid treatment at diagnosis (P = .028, .002, and .01, respectively). Regarding MR imaging features, there were statistically significant differences in the presence of linear subcortical WM susceptibility abnormality, restricted diffusion, and subcortical WM edematous changes in the acute SMART region (3/11 versus 8/9, P = .01; 0/11 versus 4/9, P = .026; and 2/11 versus 7/9, P = .022, respectively). Follow-up MRIs showed persistent susceptibility abnormality (11/11) and subcortical WM edematous changes (9/9), with resolution of restricted diffusion (4/4).

CONCLUSIONS

Age, use of steroid treatment at the diagnosis of SMART syndrome, and MR imaging findings of abnormal susceptibility signal, restricted diffusion, and subcortical WM change in the acute SMART region can be prognostic factors in SMART syndrome.

Atypical imaging findings of presumed stroke-like migraine attacks after radiation therapy syndrome in the brainstem

The authors present an atypical case of presumed stroke-like migraine attacks after radiation therapy (SMART) syndrome in the brainstem. A 29-year-old male, who had been treated with resection and subsequent craniospinal radiation for posterior fossa medulloblastoma 21 years before, presented with subacute progressive left hemiparesis evolving over 4 days. Hematological findings, cerebrospinal fluid (CSF), and electroencephalogram (EEG) were unremarkable. Magnetic resonance imaging (MRI) showed a round area of hyperintense FLAIR signal centered within the pons associated with central restricted diffusion, peripheral enhancement, and small paramagnetic low susceptibility signal foci consistent with petechial hemorrhage. Positron emission tomography (PET), perfusion MRI, and MR spectroscopy revealed no evidence of tumor recurrence. The diagnosis of SMART syndrome is presumed from the conventional and advanced imaging findings, clinical history, and clinical course.

SMART Syndrome Identification and Successful Treatment

Stroke-like migraine attacks after radiation therapy (SMART) syndrome is a rare late complication of brain irradiation. Patients commonly present recurrent attacks of headaches, seizures, and paroxysmal focal neurological deficits including aphasia, negligence, or hemianopsia. We report a 41-year-old male patient admitted to our emergency room with a reduced level of consciousness and global aphasia. One month prior to admission, he started with frequent headache attacks of moderate intensity and paroxysmal behavioral alterations, advancing to confusion, gait instability, language impairment, and somnolence. He had a history of medulloblastoma treated with surgical resection followed by craniospinal irradiation 21 years before symptom onset. After excluding more frequent causes for the patient's symptoms along with a suggestive image pattern, we started treatment for SMART syndrome with high-dose corticosteroid and calcium channel blocker verapamil. The patient gradually improved his level of consciousness and recovered from aphasia and gait instability without new seizures or neuropsychiatric symptoms. Follow-up brain magnetic resonance imaging showed resolution of the typical findings. This case displays a successful clinical evolution of a patient treated for SMART syndrome in which identification of previous radiation treatment, exclusion of other etiologies, and prompt treatment institution were key for effectively tackling this disease.

SMART (stroke-like migraine attacks after radiation therapy) syndrome responded to steroid pulse therapy: Report of a case and review of the literature

This report presents a case of stroke-like migraine attacks after radiation therapy (SMART) syndrome in a 31-year-old man in whom symptoms and radiological findings resolved with steroid pulsed therapy and reviews the literatures with special emphasis on the use of steroids against SMART syndrome. The patient had a past history of left temporal anaplastic astrocytoma and was treated with surgery followed by local 72 Gy radiation therapy and chemotherapy using Nimustine Hydrochloride. Four years after the surgery, he was suffering from subacute progressing symptoms of headache, right hemianopia, right hemiparesis and aphasia from 2 to 4 days before admission to our hospital. At first he was diagnosed as symptomatic epilepsy but after extensive examination, the final diagnosis was SMART syndrome. His symptoms soon improved with steroid pulse therapy. In the literature, steroid pulse therapy is not necessarily a standard of care for SMART syndrome, but it seemed to decrease the need of biopsy. As the lesions of SMART syndrome require differential diagnosis from recurrences, biopsy was performed in some cases. However, lack of benefit and possible detriment is reported with biopsy of SMART lesions. Through this experience we suggest that steroid pulse therapy may provide speedy recovery from symptoms, and it should be considered before other invasive investigations or treatments.

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Report a case of stroke-like migraine attacks after radiation therapy (SMART) syndrome in a 31-year-old man in whom symptoms and radiological findings resolved with steroid pulsed therapy.

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Lack of benefit and possible detriment is reported with biopsy of SMART lesions.

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Steroid pulse therapy is not necessarily a standard of care for SMART syndrome, but it seemed to decrease the need of biopsy.

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Steroid pulse therapy may provide recovery from symptoms of SMART, and should be considered before invasive investigations.

Stroke-like migraine attacks after radiation therapy syndrome: Case report and review of the literature

A 26-year-old female presented with vision loss accompanied by migraine-like headaches. A contrast-enhanced magnetic resonance imaging of the brain was performed which revealed findings suggestive of stroke-like migraine attacks after radiation therapy (SMART) syndrome. SMART syndrome is a delayed complication of brain radiation characterized by neurologic symptoms including migraine-like headaches, seizures, and hemispheric impairment. The purpose of this article is to make the readers aware of this rare complication of brain irradiation. Appropriate diagnosis of SMART syndrome is essential to avoid invasive tests.