Subacute combined degeneration of the spinal cord often manifests insidiously in middle-aged and older adults, with no significant difference between males and females. The disease usually presents as subacute or chronic, and progresses gradually. Before the appearance of neurological symptoms, most patients exhibit anemia. Some patients with mild or severe anemia due to decreased gastric acid secretion may experience fatigue, weakness, palpitations, dizziness, diarrhea, slight glossitis, and edema. In the presence of gastrointestinal diseases, patients may experience decreased appetite, constipation or diarrhea, pale lips, etc.
Neurological symptoms often manifest as symmetrical sensory abnormalities in the fingers and toes, such as tingling, numbness, and burning sensation, which are persistent and more severe in the lower limbs. Sensory abnormalities can extend upwards to the trunk, and the objective examination of the distal extremities is usually normal. A few patients have symmetrical glove or sock-like sensory impairment. With the gradual damage to the posterior column of the spinal cord, there may be clumsy limb movements, tendency to fall, walking with a sensation of stepping on cotton, difficulty in closing eyes or walking in the dark. Motor disorders usually appear later than sensory disorders, and the lower limbs may present with incomplete spastic paraplegia. Physical examination may show weakness in both lower limbs, increased muscle tone, hyperreflexia, and positive pathological signs.
About535% of patients experience optic atrophy and bilateral central scotoma, narrowing of the visual field, decreased vision or blindness. A few patients may exhibit symptoms such as apathy, drowsiness, irritability, suspicion, depression, and unstable emotions. In severe cases, there may be mental confusion, gazing, delusions, hallucinations, paranoid tendencies, decline in cognitive function, and memory loss, which may even develop into dementia.