In this case report, we present a patient with rare diagnosis of amyotrophic lateral sclerosis (ALS). In this patient, four different neurological disorders were diagnosed in a short-time period of 8 months. The first three diagnoses, chronic low back and leg pain, a left frontal gemistocytic astrocytoma WHO grade 2 and suspected Lyme's disease, could not fully explain the signs of physical examination. Finally, the diagnosis of ALS could reduce these signs to the same denominator.