Lumbar infusion test in normal pressure hydrocephalus.
OBJECTIVE
To compare potential clinical value of plateau pressure (P(pl)), resistance to outflow (R(out)), pulse-pressure amplitude (P(plA)) and rate of pressure increase (v(P)), taken from the constant rate lumbar infusion test (LIT), as predictors for the outcome of shunt surgery.


METHODS
Recordings from preoperative LIT in 55 patients were scrutinized for the values of P(pl), P(plA), v(P) and R(out). Gait, memory, spatial capacity and reaction ability were tested before and 6 months after shunt surgery.


RESULTS
Forty-three (78%) of the patients improved. There were no statistically significant differences in P(pl), R(out), P(plA) or v(P) between improved and not improved patients. Five patients with P(pl) below 22 mmHg (the cut off level) improved after shunting, while 16 and eight patients with R(out) below the cut off levels of 18 and 14 mmHg/ml/min improved. P(plA) correlated with P(pl) and R(out) (r = 0.74 and 0.63, respectively). In the group of patients with high P(plA) (>/=20 mmHg) as many as 93% improved but a high P(plA) did not recruit more improved patients than P(pl) or R(out) alone.


CONCLUSIONS
v(P) or P(plA) does not add useful information to P(pl) for selecting patients with suspected NPH for surgery. R(out) calculations from LIT does not provide advantage over using the steady-state plateau pressure for selecting patients for surgery and may increase the risk of missing patients who should benefit from surgery.
Kahlon
B
B
Department of Neurosurgery, University Hospital, Lund, Sweden. babar.kahlon@neurokir.lu.se
Sundbärg
G
G
Rehncrona
S
S
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015984:Causality; D002555:Cerebrospinal Fluid / Q000502:physiology*; D015170:Cerebrospinal Fluid Pressure / Q000502:physiology*; D003072:Cognition Disorders / Q000134:cerebrospinal fluid / Q000175:diagnosis / Q000503:physiopathology; D005260:Female; D020233:Gait Disorders, Neurologic / Q000134:cerebrospinal fluid / Q000175:diagnosis / Q000503:physiopathology; D006801:Humans; D006850:Hydrocephalus, Normal Pressure / Q000134:cerebrospinal fluid* / Q000175:diagnosis* / Q000601:surgery; D008297:Male; D008875:Middle Aged; D018579:Patient Selection; D011237:Predictive Value of Tests; D020127:Recovery of Function / Q000502:physiology; D013129:Spinal Puncture / Q000379:methods*; D016896:Treatment Outcome; D017287:Ventriculoperitoneal Shunt / Q000592:standards