Normal Pressure Hydrocephalus (NPH) is a neurological condition that often affects older adults, characterized by a specific set of symptoms: urinary incontinence, cognitive decline, and a distinctive walking problem. This article focuses on the gait disturbance, a unique walking difficulty associated with NPH that can significantly impact daily life.
Defining Characteristics of the Gait
The walking pattern associated with Normal Pressure Hydrocephalus is often described as a “magnetic gait,” where the feet appear stuck or glued to the floor. This results in small, shuffling steps that barely clear the ground.
Individuals often adopt a wide-based stance for enhanced stability. Difficulty initiating movement, known as “gait ignition failure” or “start hesitation,” is common. Turning is also challenging; rather than a smooth pivot, turns are accomplished with small, slow steps, often called “en bloc” turning. The overall gait is slow, with reduced stride length and step height, often resembling an apraxia of gait.
The Underlying Cause in the Brain
Cerebrospinal fluid (CSF) cushions the brain and spinal cord, circulating within and around these structures. In NPH, impaired CSF absorption leads to excessive accumulation. This buildup causes the ventricles, fluid-filled cavities in the brain, to gradually enlarge.
The enlarged ventricles exert pressure on surrounding brain tissue. They specifically compress motor fibers controlling leg movement, located near these spaces. This pressure disrupts signals necessary for coordinated walking, disproportionately affecting the legs. The gradual nature of this fluid accumulation often allows intracranial pressure to remain within the normal range, despite the ventricular enlargement, leading to the “normal pressure” designation.
The Diagnostic Pathway
Diagnosing Normal Pressure Hydrocephalus begins with a thorough medical history and a neurological examination. Clinicians look for characteristic symptoms: gait disturbance, cognitive changes, and urinary issues. Brain imaging, such as MRI or CT scans, is then performed to visualize the enlarged ventricles, a hallmark sign.
A key diagnostic step is the high-volume lumbar puncture or spinal tap. During this procedure, a thin needle is inserted into the lower back to remove 30-50 milliliters of CSF. The aim is to observe if temporarily reducing fluid volume and pressure improves gait, assessed before and after the procedure. A positive response, where walking improves even briefly, strongly supports an NPH diagnosis and suggests potential benefit from further treatment.
Treatment to Improve Mobility
The primary treatment for Normal Pressure Hydrocephalus is the surgical placement of a ventriculoperitoneal (VP) shunt. This thin, flexible tube is surgically implanted to create an alternative pathway for excess cerebrospinal fluid. One end of the shunt is placed in a brain ventricle, and the other is tunneled under the skin to the abdominal cavity.
Once in the abdomen, the excess CSF is absorbed by the body. By continuously draining fluid, the shunt reduces enlarged ventricles and alleviates pressure on brain’s motor fibers. This pressure reduction helps restore proper signaling to the legs, often significantly improving walking ability. Gait is frequently the first and most responsive symptom to improve after successful shunt placement, with many patients showing improvement within days to weeks. Physical therapy may also be recommended post-surgery to help individuals regain strength, balance, and confidence.