Yes, B12 deficiency-related peripheral neuropathy commonly causes both difficulty dorsiflexing the ankles and pins-and-needles sensations in the arms and hands.
Clinical Presentation
The neurological manifestations you describe are classic features of B12 deficiency neuropathy. According to the most recent NICE guidelines, pins and needles or numbness (paraesthesia) are explicitly listed as common neurological symptoms related to peripheral neuropathy from B12 deficiency 1. The guidelines also emphasize that impaired gait and balance issues are characteristic features 1.
Specific Manifestations
Motor weakness affecting ankle dorsiflexion:
- Difficulty dorsiflexing the ankle is a well-documented finding in B12 deficiency neuropathy
- Research demonstrates that muscle power recovery follows a specific sequence: proximal muscles recover first, followed by hands, then plantar flexion, and finally dorsiflexion of the feet—making ankle dorsiflexion one of the last functions to recover 2
- This motor weakness is part of a sensorimotor axonal polyneuropathy pattern 3, 4
Sensory symptoms in arms and hands:
- Paraesthesias (pins and needles) are among the most common presenting symptoms, often appearing in the upper extremities 3
- The "shuddering" quality you describe aligns with the abnormal sensory phenomena reported in B12 neuropathy
- Diminished vibratory sensation and proprioception in the extremities are the most common objective findings 3
Neurophysiological Pattern
The underlying pathology is a sensorimotor axonal polyneuropathy with predominantly sensory involvement 3, 4. Electrophysiological studies show:
- Absent or diminished amplitudes of sensory and motor action potentials (particularly in lower extremities)
- Normal or near-normal nerve conduction velocities in most cases
- Evidence of denervation in lower extremity muscles 4
Critical Clinical Pitfalls
Important caveat: B12 deficiency neuropathy can occur even with normal hematological parameters. In 27.4% of cases, the hematocrit is normal, and in 23% the mean corpuscular volume is normal 3. This means you cannot rule out B12 deficiency based on normal blood counts alone.
Duration matters significantly: The severity of neurologic dysfunction correlates directly with symptom duration before diagnosis 3. Delayed diagnosis in nonanemic patients frequently leads to neurologic progression despite normal blood counts 3. The median symptom duration before diagnosis is 4 months, but longer delays worsen outcomes 3.
Prognosis
Recovery is expected with treatment but follows a predictable pattern. Complete recovery occurs in approximately 47% of cases, with 91% showing at least 50% improvement in neurologic severity scores 3. However, the extent of recovery is inversely related to symptom duration—emphasizing the importance of early diagnosis and treatment 3.