Dynamics of cerebral blood flow and metabolism in patients with cranioplasty as evaluated by 133Xe CT and 31P magnetic resonance spectroscopy.

Abstract

Objective-Prolonged improvement in neurological and mental disorders has been seen after only cranioplasty in patients initially treated with external decompression for high intracranial pressure. The objective was to evaluate, using 133Xe CT and 31P magnetic resonance spectroscopy (MRS), how restoring the bone itself can influence cerebral blood flow and cerebral energy metabolism after high intracranial pressure is attenuated. Methods-Seven patients (45-65 years old) who had undergone external decompression to prevent uncontrollable intracranial hypertension after acute subarachnoid haemorrhage were evaluated. Cerebral blood flow and metabolic changes were evaluated before and after cranioplasty. Results-The ratio of phosphocreatine to inorganic phosphate (PCr/Pi), which is a sensitive index of cerebral energy depletion, was calculated and ,3-ATP was measured. The cerebral blood flow value in the thalamus was normalised, from 44 (SD 9) to 56 (SD 8) ml/100 g/min (P < 0.01) and the value in the hemisphere increased from 26 (SD 3) to 29 (SD 4) ml/100 g/min on the side with the bone defect. The PCr/Pi ratio improved greatly from 2 53 (SD 0'45) to 3'01 (SD 0.24) (P < 0.01). On the normal side, the values of cerebral blood flow and PCr/Pi increased significantly (P < 0'01) after cranioplasty, possibly due to transneural suppression. The pH of brain tissue was unchanged bilaterally after cranioplasty. Conclusion-Cranioplasty should be carried out as soon as oedema has disappeared, because a bone defect itself may decrease cerebral blood flow and disturb energy metabolism.(7 Neurol Neurosurg Psychiatry 1996;61: 166-171) pressive craniotomy remains controversial. Some authors found that morbidity was increased in survivors although decompressive craniectomy reduced the mortality rate, probably because it reduced the adverse effects of severe cerebral oedema and swelling.i"2 Many patients with severe head injury or massive cerebral infarction undergo external decompression as a treatment.However, little is known about how a bone defect itself can influence cerebral blood flow and cerebral energy metabolism after high intracranial pressure is normalised. Prolonged improvement in neurological and mental disorders has been seen only after cranioplasty in patients treated initially with external decompression for high intracranial pressure.'3-'7 The objective of the present study was to measure cerebral blood flow and metabolic changes, using '33Xe CT and 31P magnetic resonance spectroscopy (MRS), before and after cranioplasty to evaluate whether the brain would recover after attenuation of high intracranial pressure, by restoration of the bone itself. Materials and methodsSeven patients (45-65 years old) were selected who had undergone clipping and external decompression to prevent uncontrollable

Effective ICP Reduction by Decompressive Craniectomy in Patients with Severe Traumatic Brain Injury Treated by an ICP-Targeted Therapy

“…Late after craniectomy, a reduced CBF has been shown not just in the brain underlying the craniectomy but also in the brain contralateral to the craniectomy. These changes seem to normalize after cranioplasty (Yoshida et al, 1996;Winkler et al, 2000). Thus, we recommend that "prophylactic craniectomies" be avoided.…”

Complications of decompressive craniectomy for traumatic brain injury

“…20 Decompressive craniectomy also induces a hyperemic response as evidenced by 99m Tc SPECT, 31 P MR imaging, and 133 Xe CT studies demonstrating augmentation of CBF as well as cerebral metabolism. 96,101 Physiological monitoring using CBF, transcranial Doppler, and brain tissue oxygen probes has demonstrated increased CBF and brain tissue oxygen following decompressive craniectomy. 7,39,80 Cerebrovascular reactivity is also impaired for the first 24 hours, trending toward a return to intact autoregulation within the first 72 hours following decompressive craniectomy.…”

Unexpected complications immediately after cranioplasty

“…In our review of published work, we found nine cases of midline shift prior to surgery (47.4%), 10 cases of prior shunt surgery (52.6%), and 15 cases of prior midline shift or shunt surgery (78.9%) (Table 1). Yoshida et al 2. reported increased cerebral blood flow and metabolism in SSFS.…”