Case History/examination:
On 22 December 2019, a 79 years-old Iranian gentleman was referred to our hospital for diagnostic lumbar tap. He was a building painter and had an educational level of 6 years Primary School. The symptoms were begun since one year ago, primarily urinary incontinence and then gait disturbance. In addition, his family members noticed gradual decline in cognitive function, in the form of repeated questions and statements, word finding difficulty and time and place disorientation for recent several months. There was also some history of visual hallucination and rapid eye movement (REM) sleep behavior disorder. The past medical history was positive for diabetes mellitus, hypertension and cardiac arrhythmia that underwent permanent pacemaker. His medications included rivaroxaban, insulin, bisoprolol, valsartan, simvastatin, clonazepam and duloxetine. The physical examination revealed positive Myerson sign, absent ankle reflex, stocks and gloves hypoesthesia, and mild tremor in left hand. There was no rigidity, bradykinesia, ideomotor and ideational apraxia, and grasp and snout reflexes. Standing posture was slightly stooped with prominent postural instability. The walking was laborious needs help and consisted of wide based gait, very short steps and shuffling, in favor of frontal lobe gait. Neuropsychological assessment showed impairment in memory, attention and visuospatial domains. The total score of Mini-Mental Status Exam (MMSE) and of Montreal Cognitive Assessment (MoCA) were 19 and 14 out of 30, respectively.