**8. Predictors of shunt efficacy**

Apart from imaging findings and CSF tap test, there are other variables that can influence outcome after shunt surgery. Knowledge of these factors is important, and, when used in conjunction with diagnostic guidelines, can add weight to the decision‐making process. Several factors have been associated with either good or poor outcomes. These are summarised in **Table 2**.

The presence of white matter changes is of unclear significance in predicting outcome. The absence of white matter and severe periventricular signals on T2‐weighted imaging studies was associated with a good response to shunt placement [71]. The degree of periventricular and deep white matter lesions was shown to be inversely correlated with the degree of clinical improvement in 41 patients [72]. However, as mentioned earlier, Tullberg et al. [51] found that conventional MRI could not reliably differentiate between the causes of white matter changes and that the presence of DWMH or subcortical lacunar infarctions in NPH did not predict a poor outcome from shunt surgery [11]. These patients should not be denied surgery on the basis of these findings alone [11].


**Table 2.** Factors influencing the outcome of shunt surgery.
