Objective: To present an alternative surgical technique in treating
cases of Chiari I Malformation with mild-to-moderate syringomyelia after
decompressive suboccipital craniectomy: incising only the outer layer of
the dura mater, then dissecting it from the inner layer without opening
the latter. Methods and Results: We utilized this technique in a short
series of three cases who were admitted in our department for mild
symptoms such as intermittent headache and dissociated sensory loss in
the upper limbs, caused by a Chiari Malformation Type I. The patients
were placed in the sitting position. We performed a reduced median
suboccipital craniectomy and resection of the posterior arch of C1
adapted to the level of tonsil descent, from a limited superior half to
a complete resection. Afterwards, we incised the outer dural layer,
while sparing the inner one. Using a fine dissector, we then split apart
the outer and inner layers to the margin of the craniectomy. Through the
transparency of the inner layer and the arachnoid, the cerebellum and
the medulla were visible and pulsating. An autologous fascia duraplasty
was then performed. The postoperative course was favorable in all cases,
patients being discharged without any deficits and with complete symptom
resolution. Conclusions: Interlayer dural split technique can be used
effectively in treating symptomatic cases of type I Chiari malformation
in adults, with mild-to-moderate syringomyelia. It is less invasive than
opening the dura and possibly more effective than decompressive
craniectomy and C1 laminectomy alone. This technique must be validated
in a larger case-control series.
Interlayer dural split technique for Chiari I malformation treatment in adult—Technical note