Neurological changes and hip prosthesis: consider cobalt toxicity

July 26, 2011, 10:22 pm

★★★★☆

Neurotoxicity of cobalt. Catalani S et al. Hum Exp Toxicol 2011 Jul 5. [Epub ahead of print]

Abstract

It is important that clinicians be important with the neurological manifestations of cobalt toxicity, since some metal-on-metal hip protheses can deteriorate releasing large amounts of the metal into surrounding tissues and the blood.  Pain at the site of hip replacement can herald deterioration. The fact that relatively little has been written on this makes this comprehensive review article especially welcome.

Manifestations of cobalt neurotoxicity include:

  • optic nerve damage and retinopathy with decreased visual acuity
  • bilateral nerve deafness and tinnitus
  • polyneuropathy (sensory and motor)
  • cognitive impairment and memory loss
  • tremor

Other sequelae of cobalt toxicity include hypothyroidism and cardiac dysfunction.

Mechanisms of neurological damage in cobalt toxicity may include generation of reactive oxygen species, depletion of neurotransmitters, demyelination, and mitochondrial impairment. Patients seem to improve symptomatically once the deteriorating metal hip prosthesis is replaced.

The key take-home lesson here: Any patient with a history of hip replacement and any neurological symptoms should be evaluated to determine the exact prosthesis involved, as well as cobalt levels.

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