A 65-year-old woman is evaluated for worsening urinary urgency and incontinence. The patient has had no abdominal pain, dysuria, or changes in urinary frequency. On several occasions, she has urinated involuntarily, which she attributes to an inability to walk quickly to the bathroom. The patient feels unsteady while ambulating and walks slowly with small steps. Her family also reports that she has become forgetful and has difficulty planning and executing various activities that she used to perform regularly. Medical history is notable for hypertension. The patient does not use tobacco, alcohol, or illicit drugs. Vital signs are within normal limits. Cardiopulmonary, abdominal, and genitourinary examinations show no abnormalities. Neurological examination shows impaired attention and short-term memory. MRI of the brain reveals chronic white matter changes with no infarction, hemorrhage, or mass lesions. There is diffuse ventriculomegaly with no sulcal enlargement. Which of the following is the most likely underlying cause of this patient's urinary incontinence?

Question

A 65-year-old woman is evaluated for worsening urinary urgency and incontinence.  The patient has had no abdominal pain, dysuria, or changes in urinary frequency.  On several occasions, she has urinated involuntarily, which she attributes to an inability to walk quickly to the bathroom.  The patient feels unsteady while ambulating and walks slowly with small steps.  Her family also reports that she has become forgetful and has difficulty planning and executing various activities that she used to perform regularly.  Medical history is notable for hypertension.  The patient does not use tobacco, alcohol, or illicit drugs.  Vital signs are within normal limits.  Cardiopulmonary, abdominal, and genitourinary examinations show no abnormalities.  Neurological examination shows impaired attention and short-term memory.  MRI of the brain reveals chronic white matter changes with no infarction, hemorrhage, or mass lesions.  There is diffuse ventriculomegaly with no sulcal enlargement.  Which of the following is the most likely underlying cause of this patient's urinary incontinence?

Quizplus · Accepted Answer

11ec160b_39d7_ad5d_9249_2d609c80ab43_MD0001_00 This patient with impaired memory and cognition, unsteady gait, and urinary incontinence has ventriculomegaly without sulcal enlargement on MRI, which is characteristic of normal pressure hydrocephalus (NPH). NPH can occur due to decreased absorption of cerebrospinal fluid (CSF) by the arachnoid granulations (eg, fibrosis from previous cerebral inflammation or bleeding) with gradual accumulation of CSF in the ventricular system. The lateral ventricles expand, resulting in normal intracranial pressure and stretching the descending cortical fibers (corona radiata). Interruption of these pathways, along with impairment of cortical and subcortical function, leads to the classic triad of NPH symptoms (dementia, gait disturbance, urinary incontinence). The cerebral cortex (through the pontine micturition center) regulates the micturition reflex, which is an autonomic spinal reflex mediated by the neurons in the sacral spinal cord. In NPH, the lack of cortical inhibition results in detrusor muscle hyperactivity. This leads to urinary urgency, which can be worsened by gait abnormalities that limit a patient's ability to quickly get to a bathroom (urge incontinence). Progressive frontal lobe impairment leads to the inability to recognize urinary urge, uncontrolled urination, and a lack of concern as the disease progresses. (Choice A) Cerebellar dysfunction can cause an ataxic gait, dysarthria, and intention tremors. Memory dysfunction and urinary incontinence are more indicative of cerebral impairment. NPH typically spares cerebellar function. (Choice B) Compression of the reticular formation can occur with brainstem herniation, leading to loss of consciousness and coma. (Choice C) Impaired basal ganglia signaling is characteristic of Parkinson disease, which can result in ataxia with a slow gait. However, cogwheel rigidity and resting tremor would be prominent and dementia and urinary incontinence would not be expected until later in the disease course. (Choice D) Spinal cord damage is a common cause of incontinence with gait impairment. However, spinal cord injury also frequently causes lower extremity weakness and is not associated with cognitive impairment. Educational objective: Normal pressure hydrocephalus occurs due to decreased cerebrospinal fluid absorption, resulting in ventriculomegaly with normal intracranial pressure. This causes stretching of the descending cortical fibers (corona radiata) from the frontal lobe and contributes to the classic triad of symptoms (ie, dementia, gait abnormalities, urinary incontinence). Loss of cortical inhibition of the sacral micturition center leads to urge incontinence.

A 65-Year-Old Woman Is Evaluated for Worsening Urinary Urgency and Incontinence