Towards waterjet dissection in neurosurgery: experimental in-vivo results with two different nozzle types

A laser-induced pulsed water jet for layer-selective submucosal dissection of the esophagus

Background and aims: Conventional water jet devices have been used for injecting fluid to lift up lesions during endoscopic submucosal dissection or endoscopic mucosal resection procedures. However, these devices cannot dissect the submucosal layer effectively. Here we aim to elucidate the dissection capability of a laser-induced pulsed water jet and to clarify the mechanism of dissection with layer selectivity. Materials (Subjects) and methods: Pulsed water jets were ejected from a stainless nozzle by accelerating saline using the energy of a pulsed holmium: yttrium-aluminum-garnet laser. The impact force (strength) of the jet was evaluated using a force meter. Injection of the pulsed jet into the submucosal layer was documented by high-speed imaging. The physical properties of the swine esophagus were evaluated by measuring the breaking strength. Submucosal dissection of the swine esophagus was performed and the resection bed was evaluated histologically. Results: Submucosal dissection of the esophagus was accomplished at an impact force of 1.11-1.47 N/pulse (laser energy: 1.1-1.5 J/pulse; standoff distance: 60 mm). Histological specimens showed clear dissection at the submucosal layer without thermal injury. The mean static breaking strength of the submucosa (0.11 ± 0.04 MPa) was significantly lower than that of the mucosa (1.32 ± 0.18 MPa), and propria muscle (1.45 ± 0.16 MPa). Conclusions: The pulsed water jet device showed potential for achieving selective submucosal dissection. It could achieve mucosal, submucosal, and muscle layer selectivity owing to the varied breaking strengths.

Waterjet dissection of peripheral nerves: an experimental study of the sciatic nerve of rats

BACKGROUND

Although waterjet dissection has been well evaluated in intracranial pathologies, little is known of its qualities in peripheral nerve surgery. Theoretically, the precise dissection qualities could support the separation of nerves from adjacent tissues and improve the preservation of nerve integrity in peripheral nerve surgery.

OBJECTIVE

To evaluate the potential of the new waterjet dissector in peripheral nerve surgery.

METHODS

Waterjet dissection with pressures of 20 to 80 bar was applied on the sciatic nerves of 101 rats. The effect of waterjet dissection on the sciatic nerve was evaluated by clinical tests, neurophysiological examinations, and histopathological studies up to 12 weeks after surgery.

RESULTS

With waterjet pressures up to 30 bar, the sciatic nerve was preserved in its integrity in all cases. Functional damaging was observed at pressures of 40 bar and higher. However, all but 1 rat in the 80 bar subgroup showed complete functional regeneration at 12 weeks after surgery. Histopathologically, small water bubbles were observed around the nerves. At 40 bar and higher, the sciatic nerves showed signs of direct nerve injury. However, all these animals showed nerve regeneration after 12 weeks, as demonstrated by histological studies.

CONCLUSION

Sciatic nerves were preserved functionally and morphologically at pressures up to 30 bar. Between 40 and 80 bar, reliable functional and morphological nerve regeneration occurred. Waterjet pressures up to 30 bar might be applied safely under clinical conditions. This technique might be well suited to separate intact peripheral nerves from adjacent tumor or scar tissue. Further studies will have to show the clinical relevance of these dissection qualities.

Water jet dissection in neurosurgery: an update after 208 procedures with special reference to surgical technique and complications

BACKGROUND

Water jet dissection represents a promising technique for precise brain tissue dissection with preservation of blood vessels. In the past, the water jet dissector has been used for various pathologies. A detailed report of the surgical technique is lacking.

OBJECTIVE

The authors present their results after 208 procedures with a special focus on surgical technique, intraoperative suitability, advantages, and disadvantages.

METHODS

Between March 1997 and April 2009, 208 patients with various intracranial neurosurgical pathologies were operated on with the water jet dissector. Handling of the device and its usefulness and extent of application were assessed. The pressures encountered, potential risks, and complications were documented. The patients were followed 1 to 24 months postoperatively.

RESULTS

A detailed presentation of the surgical technique is given. Differences and limitations of the water jet dissection device in the various pathologies were evaluated. The water jet dissector was intensively used in 127 procedures (61.1%), intermittently used in 56 procedures (26.9%), and scarcely used in 25 procedures (12%). The device was considered to be very helpful in 166 procedures (79.8%) and helpful to some extent in 33 procedures (15.9%). In 8 (3.8%) procedures, it was not helpful, and in 1 procedure (0.5%), the usefulness was not documented by the surgeon.

CONCLUSION

The water jet dissector can be applied easily and very safely. Precise tissue dissection with preservation of blood vessels and no greater risk of complications are possible. However, the clinical consequences of the described qualities need to be demonstrated in a randomized clinical trial.

New applicator improves waterjet dissection quality

OBJECTIVE

Waterjet dissection is accomplished with Helix Hydro-Jet, but a new device with improved operative handling and potentially superior dissection qualities has been developed.

MATERIALS AND METHODS

Eighty-four fresh cadaveric pig brains were simultaneously cut with Helix Hydro-Jet and Erbejet 2. A commonly used applicator and a new applicator for the Helix Hydro-Jet were directly compared to the new Erbejet 2. Under standardised conditions, different pressure levels were applied to the brain surface without arachnoids. Technical features, cutting depth, tissue damage and differences of applicators were examined.

RESULTS

Microscopic analysis of cutting depth revealed different dissection characteristics of both the devices. With the standard applicators, waterjet cutting depth was shown to be deeper and with more foaming using the Helix Hydro-Jet compared to that of the Erbejet 2. With the new applicators, less foaming and a lower and more linear increased cutting depth were observed with the Helix Hydro-Jet, very similar to the superior qualities shown by the Erbejet 2.

CONCLUSIONS

The new developed applicator of the Erbejet 2 also improves the intraoperative results of the so far applied Helix Hydro-Jet. The new Erbejet 2 provides some advantages for practicability; but in combination with the new applicator, the Helix Hydro-Jet accomplished almost identical superior dissection qualities of the Erbejet 2.