Authors examined the spinal arachnoidal spaces in the above mentioned conditions in order to examine the cerebrospinal fluid (CSF) circulation.

Method: 23 infants (12 normal and 11 sick: 8 PHH, 2 infections, 1 brain tumor) were examined between the ages of 4-6 weeks. Patients were lying in prone position. Examination were performed by ATL UM 9 HDI equipment with 5-10 Mhz linear transducer. Echogenecity of the dorsal and ventral arachnoidal spaces were evaluated in longitudinal and axial sections.

Results: in the control group (12 children) we found echofree ventral and dorsal subarachnoidal spaces always. In the 8 PHH cases only one case was normal, in 7 patients echodensity was found in the dorsal subarachnoidal space. One of the infectious patients both arachnoidal spaces were echodens and the other patient has had echodensity only in the dorsal arachnoidal space. In the patient with tumor the dorsal arachnoidal space was echodens.

Conclusion: Our finding indicates that “sludge” formation in the dorsal arachnoidal space leads to the alteration of the CSF circulation and might have role: (1) in the pathogenesis of the PHH; (2) might explain incorrect negative results (pressure, blood, protein, etc.) of the lumbar puncture (Lp); (3) can explain the unsuccessful therapeutic Lp drainage of the CSF in order to decrease the hydrocephalus. Authors opinion the ultrasound examination of the spine is a useful diagnostic procedure for the examination of the disturbance of the CSF circulation.