A central nervous system metastasis of melanoma with stroke‐like onset of left‐lower quadrantanopsia

Abstract “Stroke mimics” mean diseases presenting with acute neurological impairments that are taken for stroke. Discriminating them is crucial to avoid improper treatment or delayed correct treatment. We describe a 48‐year‐old woman presenting with a sudden onset of scintillating scotoma and left‐lower quadrantanopsia. Hyperacute cerebral infarction was suspected. However, brain magnetic resonance imaging (MRI) revealed a mass at the cortico‐medullary junction in the right occipital lobe. We diagnosed her as metastatic melanoma. We suspected that neurological deficits can be attributed to seizure, and therefore introduced levetiracetam. She showed neurological improvement immediately. Our case demonstrated the importance of considering brain tumor as a differential diagnosis in patients presenting with acute‐onset neurological deficits. In addition to appropriate treatment of tumor, the use of newer antiepileptic drugs resulted in good neurological prognosis in metastatic brain tumors.


Abstract
"Stroke mimics" mean diseases presenting with acute neurological impairments that are taken for stroke. Discriminating them is crucial to avoid improper treatment or delayed correct treatment. We describe a 48-year-old woman presenting with a sudden onset of scintillating scotoma and left-lower quadrantanopsia. Hyperacute cerebral infarction was suspected. However, brain magnetic resonance imaging (MRI) revealed a mass at the cortico-medullary junction in the right occipital lobe. We diagnosed her as metastatic melanoma. We suspected that neurological deficits can be attributed to seizure, and therefore introduced levetiracetam. She showed neurological improvement immediately. Our case demonstrated the importance of considering brain tumor as a differential diagnosis in patients presenting with acute-onset neurological deficits. In addition to appropriate treatment of tumor, the use of newer antiepileptic drugs resulted in good neurological prognosis in metastatic brain tumors.

K E Y W O R D S
central nervous system metastasis, magnetic resonance imaging, melanoma, stroke mimics, visual symptom signs were within normal limit. Neurological examination revealed left-lower quadrantanopsia, horizontal gaze palsy, and disturbance of attention. Her National Institute of Health Stroke Scale (NIHSS) was 4. We considered undergoing thrombolytic therapy with the use of tissue plasminogen activator.
We performed brain MRI immediately. However, contrary to our expectation, it showed a hypointense lesion in the right occipital lobe on diffusion-weighted images and fluid-attenuated inversion recovery. We made the diagnosis of melanoma CNS metastases. Stroke-like episode was speculated to be induced by a seizure-like mechanism from metastatic lesion. The patient was treated with levetiracetam, concentrated glycerin, fructose, carbazochrome, and tranexam immediately after admission. Quadrantanopsia and gaze palsy gradually subsided, disappearing 2 days after admission. She was discharged from our hospital 7 days after admission. Subsequently, stereotactic radiation therapy was performed at another hospital for 3 days, and follow-up MRI after 3 months from admission showed the reduction in the size of lesion. The lesion was surgically resected 6 months after admission. For the next 1 year, the patient still followed an uneventful course without any recurrence of metastasis, seizure recurrence, or neurological deficits. One and a half years later after admission, the patient experienced recurrence of melanoma with multiple brain metastases. On brain MRI, hydrocephalus and melanomatosis cerebri were not observed. The patient eventually died 2 years after discharge from our department because of multiple-organ failure.

| D ISCUSS I ON
Stroke mimics account for 20%-25% of suspected stroke cases in the UK 1 and 8.8% of cases in Japan. 2 Though the common correct diagnoses were different among reports, brain tumors account for a considerable proportion of stroke mimics (Table 1).
Misdiagnosis might lead to improper treatment of the disease, especially when they came within 4.5 hours from onset, and therefore, thrombolytic therapy was considered.
With regard to brain tumor, most patients present with subacute or chronic time course. On average, symptoms developed approximately 3 weeks before the diagnosis of brain metastases (median 2 weeks). 3 However, about 5%-10% of tumors present with a stroke-like time course. 4 Lewis et al reported that 11 out of 224 (5%) patients with brain tumors were initially diagnosed as "stroke."  (Table S1). The speculated mechanisms include postseizure paralysis, focal inhibitory seizure, acute intracranial pressure changes and consequent reduced cerebral blood flow, vascular steal phenomenon, acute hemorrhage, vascular compression and resultant infarction, and tumor embolus. 5 Seizure is a common manifestation of brain tumors. Patients with metastatic melanoma are most likely to develop seizures, with 67% of all cases. 6 Seizure control can be achieved by AEDs in addition to antitumor treatments including surgery, radiotherapy, and chemotherapy. Classical AEDs (eg, carbamazepine, phenytoin, and sodium valproate) failed to control brain tumor-related seizures because of side effects, difficulty of maintaining therapeutic serum antiepileptic drug levels, changes in plasma albumin levels, and drug interactions. 7 Neurological prognosis was often poor. Recently, although there are no satisfactory randomized controlled clinical trials, 8 several prospective series suggest newer AEDs lead to lower risk of seizures and longer seizure-free period compared to classical AEDs in patients with primary brain tumors (Table S2), 9 and possibly metastatic brain tumors. 10 The good neurological prognosis of the patient and the absence of recurrence could be achieved by appropriate treatment of metastatic lesion and medication with newer AEDs.

| CON CLUS ION
This report highlights the importance of considering brain tumor as a differential diagnosis of patients with acute-onset neurological deficits. Non-negligible proportion of brain tumors present with strokelike episodes. Newer AEDs in addition to tumor-oriented treatments could result in good neurological prognosis.

ACK N OWLED G EM ENT
None.