Medical Mystery of the Week

    You have recieved your COVID19 immunizations and have returned to your outpatient practice. Your are examining a 70-year-old man with a 10-year history of a refractory depression coupled in the past several years with an unsteady gait, frequent falls, and bouts of urinary incontinence. Your neurological examination is notable for his depression, mild memory loss, and an unsteady gait that is slow to start, shuffling, and characterized by small steps and his turning on the "anchored" foot.

   You perform a lumbar puncture and the opening pressure and analysis of the cerebral spinal fluid are both normal. The results of an axial fluid-attenuated inversion recovery MRI image (Panel A) and a T2-weighted MRI image (Panel B) are shown below.
   What is your diagnosis, what test(s) would you order to confirm your suspicions, and what treatment, if any, do you recommend?

The arrow head points to an old lacunar infarct in the corona radiata; the arrows point to scattered hyperintensities suggestive of small-vessel ischemic changes.

DIAGNOSIS: Normal pressure hydrocephalus (NPH). The present case has the classic triad of urinary incontinece, gait instability and cognitive impairment ("wet, wobbly and wacky") and a normal opening CSF pressure that characterizes NPH. Characteristically, his gait is characterized by small (petite) steps, a narrow and unsteady turning angle around the anchored foot, with his feet grasping the floor as though they are magnitized. 
   Diagnostic criteria for NPH include: 1. Insidious progression of symptoms over ≥ 3 months; 2. On lumbar puncture, no elevation of opening pressure; 3. On CT or MRI of the head, an Evans index of ≥ 0.30, temporal horn enlargement, periventricular signal changes, periventricular edema, or an aqueductal or fourth ventricular flow void; 4. On MRI of the head, an acute callosal angle (no minimum required); 5. On clinical examination, gait dysfunction and either urinary incontinence or cognitive dysfunction; and 6. Workup ruling out other possible neuromedical contributors (e.g., a structural lesion or congenital aqueduct stenosis). The diagnosis of NPH is confirmed by showing clinical improvement upon removal of 30-50 ml of CSF over a period of 4-5 days.
   The treatment of NPH is ventriculoperitoneal (VP) shunting, preferably using programmable valves; when the peritoneal space is not suitable due to scarring, another space such as the pleural cavity or the bloodstream may be used.
   The presented case showed marked improvement following CSF volume reduction and underwent successful VP shunting.

Case citation: Marouf F, Glover M, Wininger B, Curry W T. Case 10-2021: A 70-year-old man with depressed mood, unsteady gait, and urinary incontinence. N Engl J Med 2012;384:1350-1358.