A 73-year-old man is brought to the emergency department by his daughter for mild confusion, double vision, and frequent falls over the past 2-3 weeks. He has also been having headaches, decreased appetite, and nausea. His past medical history is significant for diet-controlled type 2 diabetes mellitus and hypertension. The patient underwent resection of a malignant melanoma 2 months ago.
His blood pressure is 142/88 mm Hg and heart rate is 67/min. He appears comfortable and answers questions appropriately. There is no nuchal rigidity. Neurologic examination shows diplopia, mild weakness and spasticity of the right arm, and ataxic gait.
Which of the following is the next best step in management of this patient?

Question

A 73-year-old man is brought to the emergency department by his daughter for mild confusion, double vision, and frequent falls over the past 2-3 weeks.  He has also been having headaches, decreased appetite, and nausea.  His past medical history is significant for diet-controlled type 2 diabetes mellitus and hypertension.  The patient underwent resection of a malignant melanoma 2 months ago.
His blood pressure is 142/88 mm Hg and heart rate is 67/min.  He appears comfortable and answers questions appropriately.  There is no nuchal rigidity.  Neurologic examination shows diplopia, mild weakness and spasticity of the right arm, and ataxic gait.
Which of the following is the next best step in management of this patient?

Quizplus · Accepted Answer

This patient is presenting with likely undiagnosed metastatic melanoma and leptomeningeal carcinomatosis (LC). Patients with LC typically present with the subacute onset (days to weeks) of headache and a variety of neurologic symptoms/signs including altered mental status, seizure, and/or multifocal neurologic deficits. LC is most frequently associated with metastatic solid tumors such as breast cancer, lung cancer, and malignant melanoma. The usual first step in evaluating a patient suspected of having LC is to obtain a gadolinium-enhanced MRI of the brain and spinal cord, which has a sensitivity of 76%-87%. Typical findings include linear or nodular leptomeningeal enhancement along the surface of the brain and spinal cord, enhancement of the cranial nerves or nerve roots, and/or hydrocephalus. Diagnosis can be made in patients with known metastatic cancer who have typical clinical presentations and MRI findings. Typical findings A lumbar puncture is obtained in most patients after MRI as it increases diagnostic accuracy. However, it should be avoided in patients with large intracranial and/or spinal masses due to the risk of cerebral herniation. Furthermore, lumbar puncture performed before MRI can result in an artifact that can sometimes be confused with LC (Choice C). Typical findings include elevated opening pressure, low glucose, elevated protein, and mild lymphocytotic pleocytosis. Cytology should also be analyzed and is considered the gold standard for diagnosis (highly specific), but can be negative in up to 20% of cases. (Choice A) Empiric therapy with intravenous acyclovir is indicated for suspected herpes simplex virus (HSV) encephalitis due to the high mortality rate if treatment is delayed. Patients with HSV encephalitis can present with the rapid onset of fever, headache, altered mental status, ataxia, and flaccid paralysis. However, this patient's subacute presentation, lack of fever, and spastic muscle weakness make this diagnosis less likely. (Choice B) This patient's ataxic gait could be from a posterior fossa (cerebellar) lesion or spinal nerve root involvement. An MRI is better for evaluating posterior fossa lesions, cranial nuclei involvement, and leptomeningeal enhancement. In addition, an MRI of the spine is needed in this patient. (Choice E) Vitamin B12 deficiency would not typically cause cranial nerve involvement and symptoms of increased intracranial pressure. 12 Educational objective: Leptomeningeal carcinomatosis typically presents with the subacute onset of headache and multifocal neurologic deficits in patients with metastatic breast cancer, lung cancer, or melanoma. Diagnosis can be made with gadolinium-enhanced MRI of the brain and spinal cord. Lumbar puncture increases diagnostic accuracy but is generally performed after MRI to avoid the risk of cerebral herniation and potential for radiographic artifact. __________ References: Neoplastic meningitis: a guide to diagnosis and treatment. (http://www.ncbi.nlm.nih.gov/pubmed/11148663)

A 73-Year-Old Man Is Brought to the Emergency Department by His