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

Resolution of Refractory Status Epilepticus With Ketamine Without Intubation in a Patient With Stroke-Like Migraine Attacks After Radiation Therapy (SMART) Syndrome

Stroke-like migraine attacks after radiation therapy (SMART) syndrome is an infrequently reported complication arising years after radiation therapy that manifests as a reversible syndrome marked by migraine-like headaches, focal neurologic signs, and/or seizures. Refractory status epilepticus (RSE) associated with SMART syndrome is rare and can be challenging to treat. Valproic acid has been reported to improve seizures in RSE in SMART syndrome in a few case reports and may be ideal for SMART syndrome, given its use in the treatment of migraines and seizures. Ketamine has been used in RSE and a few instances in SMART syndrome. Here, we present a case of refractory focal status epilepticus in a patient with SMART syndrome who was treated with ketamine, which resolved seizures without the need for intubation.

A Rare Case of Diffuse Leptomeningeal and Cortical Enhancement Secondary to Stroke-Like Migraine Attacks After Radiation Therapy (SMART) Syndrome in a Patient With a History of Childhood Medulloblastoma

Stroke-like migraine attacks after radiation therapy (SMART) syndrome is a rare complication of craniospinal irradiation (CSI). Patients commonly present with headaches, seizures, and paroxysmal focal neurological deficits. There is a dearth of studies reported in the literature with an estimated fewer than 100 cases described since it was initially defined in the mid-1990s. The authors present the case of a 23-year-old patient with a history of childhood medulloblastoma and prior ventriculoperitoneal shunt (VPS), chemotherapy, and CSI who presented with headaches and new-onset seizures. Magnetic resonance imaging (MRI) of the brain showed diffuse left temporoparietal and occipital leptomeningeal and cortical enhancement. However, cerebrospinal fluid (CSF) analysis was unremarkable for neoplastic, infectious, or inflammatory etiology. Initiation of systemic steroid therapy resulted in drastic improvement of the patient's symptoms and prompted antiepileptic drug (AED) wean and persistent resolution of leptomeningeal and cortical contrast enhancement on brain MRI. When evaluating MRI evidence of leptomeningeal enhancement, neurosurgeons should consider SMART syndrome in the differential diagnosis, especially when extensive workup rules out more common causes of this finding such as leptomeningeal disease (LMD). Proper identification of SMART syndrome can lead to timely treatment, avoidance of invasive procedures such as tissue biopsy, and improved clinical outcomes.

Unexpected Cerebral Hyperperfusion after Transient Hypoperfusion Associated with Stroke-like Migraine Attacks after Radiation Therapy Syndrome

Stroke-like migraine attacks after radiation therapy (SMART) syndrome, a delayed sequela of cranial radiotherapy encountered rarely, occurs due to transient neurological deficits coupled with migraine episodes. This case report describes an occurrence of SMART syndrome in an individual 8 years after receiving medulloblastoma treatment. The subject, a 21-year-old male, experienced abrupt aphasia and right-sided hemiparesis. Arterial spin labeling (ASL) revealed initial cerebral hypoperfusion in the left temporal and parietal regions, with no tumor resurgence or notable ischemic alterations. Two days later, the symptoms disappeared completely; nevertheless, at that time, ASL presented cerebral hyperperfusion in the same lobule. The subject experienced a pulsating headache and nausea the next day. In the context of SMART syndrome, this fluctuation in cerebral blood flow indicated by ASL is a unique finding. The significance of this case lies in the documentation of the dynamic evolution of cerebral perfusion in SMART syndrome via ASL, thereby elucidating its underlying pathophysiology. As hemiplegic migraine shows a similar cerebral perfusion pattern to SMART syndrome, we inferred an unexplored but shared pathophysiology among hemiplegic migraine and SMART syndrome. Through this successful capture of these distinct cerebral blood flow alterations, from hypoperfusion to hyperperfusion, our understanding of the pathophysiological intricacies inherent to SMART syndrome will be enhanced.

Prosopagnosia: face blindness and its association with neurological disorders

Loss of facial recognition or prosopagnosia has been well-recognized for over a century. It has been categorized as developmental or acquired depending on whether the onset is in early childhood or beyond, and acquired cases can have degenerative or non-degenerative aetiologies. Prosopagnosia has been linked to involvement of the fusiform gyri, mainly in the right hemisphere. The literature on prosopagnosia comprises case reports and small case series. We aim to assess demographic, clinical and imaging characteristics and neurological and neuropathological disorders associated with a diagnosis of prosopagnosia in a large cohort. Patients were categorized as developmental versus acquired; those with acquired prosopagnosia were further subdivided into degenerative versus non-degenerative, based on neurological aetiology. We assessed regional involvement on [18F] fluorodeoxyglucose-PET and MRI of the right and left frontal, temporal, parietal and occipital lobes. The Intake and Referral Center at the Mayo Clinic identified 487 patients with possible prosopagnosia, of which 336 met study criteria for probable or definite prosopagnosia. Ten patients, 80.0% male, had developmental prosopagnosia including one with Niemann-Pick type C and another with a forkhead box G1 gene mutation. Of the 326 with acquired prosopagnosia, 235 (72.1%) were categorized as degenerative, 91 (27.9%) as non-degenerative. The most common degenerative diagnoses were posterior cortical atrophy, primary prosopagnosia syndrome, Alzheimer's disease dementia and semantic dementia, with each diagnosis accounting for >10% of this group. The most common non-degenerative diagnoses were infarcts (ischaemic and haemorrhagic), epilepsy-related and primary brain tumours, each accounting for >10%. We identified a group of patients with non-degenerative transient prosopagnosia in which facial recognition loss improved or resolved over time. These patients had migraine-related prosopagnosia, posterior reversible encephalopathy syndrome, delirium, hypoxic encephalopathy and ischaemic infarcts. On [18F] fluorodeoxyglucose-PET, the temporal lobes proved to be the most frequently affected regions in 117 patients with degenerative prosopagnosia, while in 82 patients with non-degenerative prosopagnosia, MRI revealed the right temporal and right occipital lobes as most affected by a focal lesion. The most common pathological findings in those with degenerative prosopagnosia were frontotemporal lobar degeneration with hippocampal sclerosis and mixed Alzheimer's and Lewy body disease pathology. In this large case series of patients diagnosed with prosopagnosia, we observed that facial recognition loss occurs across a wide range of acquired degenerative and non-degenerative neurological disorders, most commonly in males with developmental prosopagnosia. The right temporal and occipital lobes, and connecting fusiform gyrus, are key areas. Multiple different pathologies cause degenerative prosopagnosia.