What is a Codman in relation to neurology?

Codman in Neurology: Programmable Valve Systems for Hydrocephalus Management

In neurology, Codman refers to the Codman Hakim Programmable Valve system, which is a type of adjustable cerebrospinal fluid shunt valve used in the management of hydrocephalus that allows non-invasive pressure adjustments to optimize cerebrospinal fluid drainage. 1

Characteristics and Function

• The Codman Hakim Programmable Valve allows neurosurgeons to adjust cerebrospinal fluid pressure non-invasively in differentials of 10 mm of water within a range of 30-200 mm of water, tailoring the pressure to the patient's specific clinical needs 2
• This valve system can be reprogrammed after implantation to address issues such as overdrainage (slit ventricles) or underdrainage (persistent ventriculomegaly) without requiring additional surgery 2, 3
• The programmable feature is particularly beneficial for patients with posthemorrhagic acute hydrocephalus, subdural effusions, and arachnoid cysts 3

Clinical Applications

• For patients with slit-like ventricles (overdrainage), the Codman valve can be programmed to a higher pressure setting to reduce overdrainage and associated complications 4
• In cases of normal pressure hydrocephalus, the programmable valve allows for gradual decreasing of ventricle size by adjusting pressure settings 2
• Approximately 50% of patients with Codman valves require reprogramming of opening pressure postoperatively, highlighting the clinical utility of this adjustable feature 3

Comparison with Other Valve Types

• In randomized controlled trials, the Codman Hakim programmable valve showed comparable efficacy and safety to conventional valves, with no statistically significant difference in shunt survival between the experimental and control groups 1, 5
• Some studies have found that programmable valve placement (including Codman) was associated with a reduced risk of both overall shunt revision (35% vs 54% in nonprogrammable group) and proximal shunt obstruction (12% vs 28%) 1
• However, other studies have reported contradictory findings, with programmable valves (including Codman) having significantly lower survival rates compared to nonprogrammable valves (19.8% vs 45.8%) 1

Considerations and Limitations

• The valve is sensitive to magnetic fields, requiring confirmation of opening pressure after every magnetic resonance imaging examination 3
• At 3-Tesla MRI, the Codman valve shows minor magnetic field interactions and heating, but may require reprogramming after imaging 6
• Complications associated with the Codman valve include valve obstruction (most common), infection, and spontaneous deprogramming 3, 7
• Valve obstruction complications appear more likely in patients with brain tumors 3

Management of Slit Ventricles with Codman Valves

• For patients with slit-like ventricles and ventriculostomy catheters near the foramen of Monro, increasing the valve setting to a higher pressure is recommended as first-line intervention 4
• Anti-siphon devices can be incorporated into the Codman shunt system to reduce overdrainage complications and proximal catheter obstructions 4
• In refractory cases, conversion to a different valve type such as the Orbis-Sigma valve may be considered, as it has been associated with a lower incidence of slit-like ventricles (3.6% with Orbis-Sigma vs 10.8% with differential pressure valves) 1, 4