Space Flap for Cerebral Protection Following Decompressive Hemicraniectomy for Stroke
Condition: Infarction
MeSH terms: Infarction
Study type: Interventional

Summary: 
      In this study the investigators want to investigate to what extent the application of an
      artificial bone flape (space flap) influences the success of a decompressive craniectomy.

      In all participants, a space flap is placed immediately after removal of the skull cap. In a
      second operation, after 1-3 months, an operation is performed, in which the stored own skull
      bone is re-inserted. The artificial bone cover is removed at this point.
    

Detailed description: 
      The destruction of local brain parenchyma after cerebral infarction leads to local swelling
      within a few days. In the beginning the ischemic brain expand at the expense of the CSF and
      venous spaces. However, once these spaces are partially displaced further swelling invariably
      leads to increase of the intracranial pressure due to the limited space available inside the
      cranial vault. In cases of large infarctions this increase in intracranial pressure (ICP) may
      entail life threatening secondary injuries to the brain. The surgical removal of a large part
      of the skull (decompressive hemi-craniectomy) allows the ischemic brain to expand, therefore
      avoiding an increase of ICP and it's deleterious effects. After removal of a part of the
      skull the skin is closed again, and the skull flap is kept in sterile environment. Several
      months after decompression craniectomy patients undergo implantation of either their
      preserved bone flap or of a bone flap substitute (so-called patient specific implant, or PSI,
      mostly made out of Palacos®).

      Decompressive hemi-craniectomy comes at a cost for the patient, despite its undisputed role
      as a life saving surgery after large cerebral infarction. During the first days after surgery
      the brain may use the space freed up by bone removal. In some cases the brain may prolapse
      even further out of the cranial vault, leading to brain herniation. Brain herniation are
      common and may lead to further damage due to axonal shearing injuries in the brain, and to
      hemorrhages and infarction at the craniotomy edges. The lack of the protective skull prior to
      re-implantation of the bone flap puts the brain at risk of injuries due to falls during
      rehabilitation and exposes the brain indirectly to atmospheric pressure. Various neurological
      deficits subsumed as the syndrome of the trephined have been described in these patients. The
      symptoms of the syndrome of the trephined have in common that they appear a few weeks after
      decompression and significantly improve after re-implantation of the patient's own bone. The
      symptoms range from orthostatic headache and dizziness to motor paresis, aphasia, cognitive
      decline and brainstem compression symptoms. The pathophysiology behind the syndrome of the
      trephined can be understood as an "open box" phenomenon. After removal of the bone the brain
      is separated from the atmospheric pressure only by the skin. The skin, however, does not hold
      against atmospheric pressure and sinks into the skull cavity (sinking skin flap) once the
      brain swelling diminishes. Physiologic dynamics of the cerebrospinal fluid are deranged,
      leading to hydrocephalus, subdural hygromas and parenchymal effusions. This assumption is
      enforced by pathophysiological observations of decreased cerebral blood flow in both
      hemispheres following decompression, and normalization thereof following re-implantation of
      the bone flap.

      This pilot study aims at assessing feasibility of a change in surgical protocol. The rate of
      ICP control will be used to determine the sample size of a planned monocenter study.
    

Intervention name(s): Space Flap
Intervention type(s): Device
Intervention description(s): A space flap is formed out of Palacos®, adjusted to the skull surface with temporal augmentation
Intervention model: Single Group Assignment
Masking: None (Open Label)
Primary purpose: Treatment
Keywords: Decompressive hemi-craniectomy; bone flap