Background

Sleep disturbance is an important symptom in palliative care which impacts on daytime function and quality of life for both patients and caregivers. It is common among patients with advanced disease and has a complex and multifactorial pathophysiology. As such, the underlying aetiology of sleep disturbances can be overlooked by clinicians. We present the case of a woman in her early 50s with probable rapid-eye movement (REM) sleep behaviour disorder (RBD) due to cerebral metastases from malignant melanoma. Her symptoms were rapidly controlled with clonazepam, which was initiated early given the suspected diagnosis.

Case report

This case was a woman in her early 50s with metastatic BRAF v600e mutant cutaneous melanoma diagnosed in May 2019. After a wide local excision in 2019, she developed metastatic disease in January 2022. She commenced pembrolizumab in July 2022, which was subsequently discontinued in October 2022 due to pneumonitis and progressive disease.

She was admitted to Christchurch Hospital, New Zealand, in September 2023, with new-onset blurred vision and difficulty mobilising. CT revealed multiple new brain metastases and progression in her lung, peritoneum, spine and subcutaneous tissues over the 3 months since her previous imaging. MRI of the head confirmed a 17×13 mm right frontal lesion with localised mass effect and approximately 5 mm of leftward midline shift, a 16×12 mm left parasagittal parietal lesion, a 15×10 mm right cerebral peduncle metastasis with associated haemorrhage and a 4 mm right cerebellar and punctate left cerebellar lesion (figure 1). There was mild to moderate perilesional oedema. She was started on oral dexamethasone 12mg daily.