What neuropathic pattern is typical of diabetic polyneuropathy and how is it assessed clinically and electrodiagnostically?

What neuropathic pattern is typical of diabetic polyneuropathy and how is it assessed clinically and electrodiagnostically?

• A. Distal symmetric polyneuropathy with stocking-glove distribution; decreased vibration and pinprick; reduced reflexes; NCS shows reduced amplitudes; monofilament tests
• B. Proximal weakness with proximal atrophy
• C. Focal mononeuropathy
• D. Central demyelinating disease

Answer: (A)

The pattern most typical of diabetic polyneuropathy is a length-dependent, distal symmetric neuropathy. Long nerves are hit hardest by the metabolic and microvascular effects of chronic hyperglycemia, so symptoms start in the feet and later involve the hands, giving a stocking-glove distribution. This reflects axonal damage that progresses from the most distant nerves toward the center. Clinically, this shows up as loss of sensory function in the distal extremities. Large-fiber loss is suggested by diminished vibration and proprioception, while small-fiber loss is indicated by impaired pinprick sensation. Reflexes, especially the ankle jerk, are reduced or absent. Monofilament testing assesses protective sensation on the soles; failure to feel the monofilament indicates significant neuropathy and increased ulcer risk. Electrodiagnostically, nerve conduction studies typically demonstrate reduced amplitudes in sensory (and sometimes motor) nerves due to axonal loss. Conduction velocities may be relatively preserved early on, which supports an axonal rather than a demyelinating process. EMG may show signs of distal denervation in affected muscles. This combination—distal symmetric polyneuropathy with stocking-glove distribution, sensory loss (vibration and pinprick), decreased reflexes, and reduced amplitudes on NCS—fits the classic profile of diabetic polyneuropathy.

The pattern most typical of diabetic polyneuropathy is a length-dependent, distal symmetric neuropathy. Long nerves are hit hardest by the metabolic and microvascular effects of chronic hyperglycemia, so symptoms start in the feet and later involve the hands, giving a stocking-glove distribution. This reflects axonal damage that progresses from the most distant nerves toward the center.

Clinically, this shows up as loss of sensory function in the distal extremities. Large-fiber loss is suggested by diminished vibration and proprioception, while small-fiber loss is indicated by impaired pinprick sensation. Reflexes, especially the ankle jerk, are reduced or absent. Monofilament testing assesses protective sensation on the soles; failure to feel the monofilament indicates significant neuropathy and increased ulcer risk.

Electrodiagnostically, nerve conduction studies typically demonstrate reduced amplitudes in sensory (and sometimes motor) nerves due to axonal loss. Conduction velocities may be relatively preserved early on, which supports an axonal rather than a demyelinating process. EMG may show signs of distal denervation in affected muscles.

This combination—distal symmetric polyneuropathy with stocking-glove distribution, sensory loss (vibration and pinprick), decreased reflexes, and reduced amplitudes on NCS—fits the classic profile of diabetic polyneuropathy.