As the HGT-HIT-046 (NCT01506141) and SHP609-302 (NCT02412787) studies are completed and closed, this post-trial access (PTA) program provides TAK-609 to participants in these studies for whom the benefit:risk ratio of continued treatment with idursulfase-IT remains positive.

Inclusion Criteria:

1. Participants will have completed the treatment period of the HGT-HIT-046 (NCT01506141) or SHP609-302 (NCT02412787) study prior to the first dose on this program.
2. Participant and/or a parent(s)/legal guardian is informed of the nature of this compassionate post-trial access program and can provide written informed consent for themselves or the child to participate (with assent from the child when appropriate prior to treatment).

Exclusion Criteria:

1. Participant has a condition that in the opinion of the treating physician may compromise their safety.
2. Participant has a known hypersensitivity to idursulfase-IT or its components.