Unilateral posteroventral<unk>  can be effective at reducing Parkinsonism. However, it is associated with impaired language learning (if performed on the dominant hemisphere) or impaired visuospatial constructional ability (if performed on the non-dominant hemisphere). It can also impair executive functions. Bilateral<unk>  will not reduce Parkisonistic symptoms. It will cause severe apathy and depression, along with slurred, unintelligible speech, drooling, and pseudobulbar palsy. The surgery itself can cause complications. Damage to a blood vessel may cause intracranial haemorrhage. Damage to the optic tract can cause a permanent vision problem. Pressure on brain tissue can induce a seizure.
Pallidotomy
Cricopharyngeal myotomy
Ventriculotomy 
Lumbar–peritoneal shunt
Surgical airway management
Positive airway pressure
Cerebrospinal fluid diversion
Craniotomy