Longitudinal Flow of Cochlear Fluids

Averaged figures for calculations:

Endolymph Flow : Basally-directed 0.008 mm/min (0.0008 ul/min or 0.8 nl/min assuming 0.1 mm2 endolymph CSA)
Perilymph Flow in ST (cochlea sealed) : Apically-directed 1.6 nl/min (0.0016 ul/min)
Perilymph flow (cochlea perforated) : 0.5 ul/min from cochlear aqueduct (base of ST) to site of leak

Note that in the table below, +ve flow indicates flow towards base of cochlea, -ve flow indicates flow toward apex

Endolymph Flow Rates

Value

Species

Source

Comment
------------------------ ---------------------- ------------------------------------ ---------------------
-0.067 mm/min
SD 0.074
n=8		 guinea pig cochlea
Turn 2		 Salt & DeMott (1988) Hear Res 123, 137 NS re. 0
+ is basally-directed
-0.006 mm/min
SD 0.026
n=10		 guinea pig cochlea
Turn 1		 Salt & DeMott (1997) Hear Res 107, 29 NS re. 0
+ is basally-directed
0.007 mm/min
SE 0.006
n=13		 guinea pig cochlea
turn 2		 Salt & DeMott (1995) Hear Res 90,12 NS re 0
+ is basally-directed
peri perfused
0.0036 mm/min guinea pig cochlea
turn 1		 Salt & Thalmann (1989) Meniere's Disease, Nadol. Ed p69 NS re. 0
0.009 mm/min guinea pig cochlea
turns 1 and 2		 Salt et al. (1986) Hear Res 23,141
0.1 mm/min guinea pig cochlea
turn 2		 Sykova et al (1988) Hear Res 28, 161
Yates et al. (1988) Hear Res 33,281		 flow between turns lower than this value
40 mm/hr
(0.67 mm/min)		 guinea pig cochlea Giebel (1982) Laryngol. Rhinol. Otol. 61, 481 Volume disturbance by injection- excluded from average

Perilymph Flow Rates - sealed cochlea

Value

Species

Source

Comment
------------------------ ---------------------- ------------------------------------ ---------------------
-1.6 nl/min guinea pig cochlea
ST, turns 1 and 2		 Ohyama et al. (1988) Hear Res 35, 119 + is basally-directed
0 guinea pig cochlea
SV, turns 1 and 2		 Ohyama et al. (1988) Hear Res 35, 119 + is basally-directed

Perilymph Flow Rates - perforated cochlea

Value

Species

Source

Comment
------------------------ ---------------------- ------------------------------------ ---------------------
-1.0 ul/min guinea pig cochlea
ST		 Ohyama et al. (1988) Hear Res 35, 119 Cochlear apex perforated
+ is basally-directed
-0.487 ul/min
SD 0.070
n=5		 guinea pig cochlea
ST		 Salt et al. (1991) Acta Otolaryngol 111, 899 apex perforated
-0.0069 ul/min guinea pig cochlea
ST		 Salt et al. (1991) Acta Otolaryngol 111, 899 apex perforated
CSF pressure released
-0.0018 ul/min guinea pig cochlea
ST		 Salt et al. (1991) Acta Otolaryngol 111, 899 apex perforated
cochlear aqueduct blocked