Pseudopheochromocytoma as a Presentation of Amyotrophic Lateral Sclerosis

Abstract

Introduction: Pseudopheochromocytoma presents as paroxysmal events of hypertension and other noradrenergic symptoms similar to pheochromocytoma (PCC) but do not meet tumoral diagnosis. Case Report: A 70-year-old Caucasian male with history of gastroesophageal reflux disease (GERD) and Barrett’s esophagus presented to the Emergency Department with fatigue, shortness of breath, palpitations, and fasciculations in the anterior chest wall. He reported recent diagnosis of PCC. Patient had episodes of non-exertional palpitations, diaphoresis, dizziness, facial flushing, and facial involuntary movement along with self-monitored average blood pressure (ABP) of 160/100 mmHg and heart rate (HR) of 90 beats per minute (bpm). Spells occurred 2 to 3 times per month at first, later increased. Between episodes self-monitored ABP was 120/70 mmHg and HR of 50 bpm and asymptomatic. He reported unintentional weight loss of 40 pounds in the same interval and newly muscle weakness that he attributed to weight loss and malnutrition. Patient had no remarkable past medical history. Medications included coq10 enzyme, glucosamine, flax seed oil, primrose oil and recently added doxazosin 1 mg tab per day. Evaluation revealed a cachectic patient (body mass index 17.46 k/m2) with normal vital signs, otherwise unremarkable physical exam except for diffuse fasciculations in chest and upper extremities. Outpatient work up included normal complete blood count, comprehensive metabolic panel, drug screening, thyroid function test. He had elevated free plasma metanephrine (FPM) of 73 pg/mL (< 57 pg/mL), free plasma normetanephrine (FPN) of 487 pg/mL (<148 pg/mL), before doxazosin. Repeated FPM of 55 pg/mL (< 57 pg/mL), FPN of 347 pg/mL (<148 pg/mL). The 24-hour urine for metanephrine was normal with total metanephrine of 157 ug/d (55-320 ug/d) and normetanephrine 432 ug/d (114-865 ug/d) with a creatinine of 900 mg/dL (800-2100 mg/d). He also had outpatient computed tomography (CT) scan of thorax, abdomen, and pelvis that was normal. Positron emission tomography CT scan did not reveal any tumors. Our initial suspicion, later confirmed with electromyography, was a neurodegenerative disease with motor neuron dysfunction. Patient was diagnosed with Amyotrophic Lateral Sclerosis (ALS) and started in riluzole with improvement of spells. Since, his muscle weakness progressed, he now requires noninvasive ventilation. Discussion: Pseudopheochromocytoma is an idiopathic disease that mimics catecholamine-secreting PCC and needs adequate and complete evaluation. Catecholamine levels can be affected by illness, stress, medications, and sample collection. In the case presented, the patient’s muscular weakness and fasciculations was caused by ALS. Neurodegenerative diseases such as ALS can cause a central nervous system stress response, consequently causing elevated norepinephrine levels.