Copper Deficiency Myelopathy (CDM) is a rare, acquired neurological disorder resulting from insufficient copper levels in the body. This condition directly affects the spinal cord, often mimicking the symptoms of Vitamin B12 deficiency. Copper is a trace element that plays a fundamental role in various biological processes, particularly within the central nervous system. CDM is a treatable cause of non-compressive myelopathy, but diagnosis is often delayed because its neurological presentation is frequently misattributed to other causes.
What Is Copper Deficiency Myelopathy?
Copper deficiency myelopathy is a syndrome marked by damage to the spinal cord and peripheral nerves when the body’s copper stores are low. Copper is a cofactor for enzymes involved in energy production and nerve sheath maintenance; its scarcity leads to a progressive breakdown of nerve tissue. The most significant damage occurs in the dorsal columns of the spinal cord, which transmit sensory information like position and vibration sense. This demyelination causes the characteristic neurological symptoms.
The clinical presentation of CDM is dominated by profound sensory ataxia, which is a loss of coordination due to a lack of proprioception. Patients commonly experience difficulty with balance and walking, often describing a spastic or unsteady gait. Numbness and tingling (paresthesia) frequently affect the upper and lower limbs in a stocking-and-glove distribution, indicating an associated peripheral neuropathy.
Copper deficiency also affects the production of blood cells, leading to associated hematological abnormalities. Anemia (a reduction in red blood cells) and neutropenia (a low count of white blood cells) are frequently observed alongside neurological symptoms. These blood issues can sometimes be mistakenly diagnosed as a myelodysplastic syndrome before the underlying copper deficiency is identified.
Identifying the Underlying Causes
Copper deficiency is rarely due to a simple lack of copper in the diet, as the element is widely distributed in food sources. The majority of cases are secondary, resulting from a disruption in the body’s ability to absorb or utilize copper. A prior history of upper gastrointestinal surgery is a common risk factor, particularly bariatric procedures like Roux-en-Y gastric bypass. These surgeries alter the anatomy of the stomach and small intestine, bypassing the primary absorption sites and leading to chronic malabsorption.
Excessive zinc intake causes acquired copper deficiency due to a competitive absorption mechanism. Zinc and copper compete for binding to metallothionein, a protein synthesized in intestinal cells. High zinc levels increase metallothionein production, which preferentially binds copper, trapping it within the cells.
The trapped copper is shed when the intestinal cells turn over, preventing its absorption. This zinc-induced deficiency can occur from long-term use of high-dose zinc supplements or exposure to zinc-containing products like denture adhesives. Malabsorption syndromes, such as celiac disease or inflammatory bowel disease, also compromise the intestinal lining, reducing copper uptake. In some cases, the specific cause of the deficiency remains unknown.
Diagnostic Procedures
Diagnosis begins with a detailed patient history to identify risk factors like prior surgery or chronic supplement use. The definitive diagnosis relies on specific laboratory blood tests measuring copper and the copper-carrying protein, ceruloplasmin. Both serum copper and ceruloplasmin levels are typically significantly reduced in patients with copper deficiency myelopathy.
Clinicians must rule out Vitamin B12 deficiency, as the symptoms and radiological findings of the two conditions are nearly identical. This is achieved by testing Vitamin B12 levels and related metabolites, which helps isolate copper deficiency as the specific cause. The presence of concurrent anemia or neutropenia can also serve as a diagnostic clue.
Magnetic Resonance Imaging (MRI) of the spinal cord is often used to visualize the damage. The MRI typically shows increased signal intensity on T2-weighted images in the dorsal columns of the cervical and thoracic spinal cord. This finding is suggestive of a myelopathy but is indistinguishable from the pattern seen in B12 deficiency. Further testing, such as nerve conduction studies, may reveal signs of a sensory-motor polyneuropathy, which frequently coexists with the myelopathy.
Treatment and Recovery
The primary management strategy for copper deficiency myelopathy is immediate copper replacement therapy to halt the progression of neurological damage. Treatment begins with copper supplementation, administered orally or intravenously depending on the severity and underlying cause. For patients with mild to moderate deficiency or those without severe malabsorption, oral elemental copper supplementation (2 to 8 milligrams daily) is the standard approach.
For those with severe malabsorption or inability to absorb oral supplements, copper may be given intravenously to bypass the compromised gastrointestinal tract. Addressing the root cause of the deficiency is a component of the treatment plan. This involves immediately stopping excessive zinc supplementation or managing underlying malabsorption disorders like celiac disease.
Monitoring involves regularly checking serum copper and ceruloplasmin levels to ensure they return to the normal range. Hematological manifestations, such as anemia and neutropenia, generally respond quickly and completely to copper replacement, often resolving within a few weeks. Early diagnosis and intervention are necessary for maximizing neurological improvement, but if treatment is delayed, some neurological deficits, particularly sensory ataxia and gait instability, may remain permanent.