Table 2 Non-invasive ICP monitoring methods

Fluid dynamics

TCD 51–55

1. Get the cerebral vessel condition, cerebral blood flow and other parameters

2. NIRs use for the earlier recognition traumatic brain injury secondary insults

1. Pathological vessels and CSF will affect the result

2. Different processing Models will get different results

3. There is plenty variation in NIRS techniques and the reference measurements

TDTD 60

Dynamic MRI 56–59

Near-infrared spectroscopy 67

Jugular bulb monitoring

Otology

Tympanic membrane displacementw 69,70

CM measurements have been routinely used for decades in audiology

1. TMD complications, long-lasting intubation may resulting auditory-tube dysfunction and insufficient middle-ear ventilation or effusion

2. TMD variability varies considerably due to spontaneous pulsing and cochlear aqueduct

3. TMD limited by daily safe noise exposure limits and sedative drugs

4. Need exclude the abnormal transmission of sound through the ear

Cochlear microphonic potential (CM) 68

Distortionproduct oto-acoustic emissions

Ophthalmology

ONSD 43–50

1. Only need commom ophthalmic examinations

2. NPI may predict patient prognosis

1. Patients with ophthalmic diseases will influce the measurement result

2. Individual differences

Neurological pupil index (NPI) 65

Spontaneous venous eye measurement

Venous opthalmodynamometry

Tonometry

Electrophysiology

Rheoencephalography (REG) 61

1.Visual evoked potential can measure the pressure of the left and right compartments separately

2.The measurement results of EIT do not depend on the operator's experience

1.Exist time delay between EEG and ICP

2.Visual evoked potential influced by anatomic injury of the visual pathway

3.Disturbed by some drugs, severe acidosis, liver func-tion damage, sedation, and anesthesia

Electroencephalogram (EEG) 62,63

Electrical impedance tomography (EIT) 66

Visual evoked potential 64

Other

Tissue resonance analysis

Innovative technology

Lack of clinical experiment need further research

Acoustoelasticity

Anterior fontanelle pressure monitoring

Skull elasticity