We report a case of a 69-year-old male who presented with pain, weakness, and clumsiness of his right hand. Initial evaluation suggested possible neoplastic process affecting his cervical spine, which was fortunately ruled out by bone biopsy. Subsequent electrodiagnostic studies and magnetic resonance imaging confirmed a lesion of the deep ulnar motor branch. Exploration of Guyon's canal was performed, and an intraneural ganglion involving the deep motor branch of the ulnar nerve was found and excised. Despite more than 14 months of symptomatic duration, the patient made a near-complete recovery with virtually no functional limitations. This provides supporting evidence for a functional benefit of intraneural ganglion excision and nerve decompression even in cases of chronic muscle atrophy.