Drainage control system for control signal generation for a drainage unit to be used in a drainage line to remove a liquid from a patient's cerebral ventricle, comprising - a pressure sensor for the time-resolved detection of a cerebral ventricle internal pressure, - a waveform candidate memory, - an evaluation unit, which is in signal communication with the pressure sensor and the waveform candidate memory, - the evaluation unit comprising -- a heart rate analysis module to determine a patient's heart rate, -- a wave phase extraction module to determine a starting time (t A) and an end time (t E) of an intracranial pressure wave synchronous to the heart rate, -- a waveform analysis module, which allocates a form of the intracranial pressure wave between the starting time and end time thus determined to a waveform determined from a plurality of waveform candidates (WF 1 -WF 5), which are stored in the waveform candidate memory, - a control signal generation module, which is in signal communication with the evaluation unit and generates a drainage control signal based on an allocation result of the waveform analysis module of the evaluation unit, - wherein an allocation is carried out in such a way that by performing a statistical evaluation of the allocation frequencies, a conclusion is drawn as to the current pressure and/or a compliance in the cerebral ventricle irrespective of potential absolute measurement drifts of the pressure sensor. - a pressure sensor for the time-resolved detection of a cerebral ventricle internal pressure, - a waveform candidate memory, - an evaluation unit, which is in signal communication with the pressure sensor and the waveform candidate memory, - the evaluation unit comprising -- a heart rate analysis module to determine a patient's heart rate, -- a wave phase extraction module to determine a starting time (t A) and an end time (t E) of an intracranial pressure wave synchronous to the heart rate, -- a waveform analysis module, which allocates a form of the intracranial pressure wave between the starting time and end time thus determined to a waveform determined from a plurality of waveform candidates (WF 1 -WF 5), which are stored in the waveform candidate memory, -- a heart rate analysis module to determine a patient's heart rate, -- a wave phase extraction module to determine a starting time (t A) and an end time (t E) of an intracranial pressure wave synchronous to the heart rate, -- a waveform analysis module, which allocates a form of the intracranial pressure wave between the starting time and end time thus determined to a waveform determined from a plurality of waveform candidates (WF 1 -WF 5), which are stored in the waveform candidate memory, - a control signal generation module, which is in signal communication with the evaluation unit and generates a drainage control signal based on an allocation result of the waveform analysis module of the evaluation unit, - wherein an allocation is carried out in such a way that by performing a statistical evaluation of the allocation frequencies, a conclusion is drawn as to the current pressure and/or a compliance in the cerebral ventricle irrespective of potential absolute measurement drifts of the pressure sensor.