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hans chiari , an austrian pathologist ( 1851 - 1916 ) , described chiari malformations and classified them into 4 types13 ) . according to this classification ; chiari type i is at least 3 mm downward displacement of cerebellar tonsils below the foramen magnum , chiari type ii is related with downward displacement of posterior fossa elements with accompanying myelomeningocele , chiari type iii is herniation of posterior fossa elements into an occipital or a cervical encephalocele , the last one is type iv seen in cerebellar hypoplasia event14 ) .
syringomyelia may accompany chiari type i malformation as in the other chiari malformation types . in the literature , craniovertebral decompression ( cvd ) and/or syringo - subarachnoid / syringo - peritoneal / syringo - cisternostomy
have been justified as the method(s ) of treatment for syringomyelia associated with chiari type i malformation9,12,14 ) . in this paper , authors define the first successful treatment of a patient with syringomyelia due to chiari type i malformation using a pre - defined new technique of syringo - subarachnoid - peritoneal shunt with t - tube , described by kim et al.11 ) .
a 34-year - old man presented to our outpatient clinic with a 3-month history of an increasing numbness and weakness in his four extremities .
magnetic resonance imaging revealed a tonsillar herniation with a large syringomyelia in the spinal cord starting from just below the foramen magnum level and ending at the level of t5 vertebral body .
somatosensory evoked potentials ( sep ) were abnormal ( increased n13 - 20 interval , reduced cortical amplitude from posterior tibial nerve ) .
we planned syringo - subarachnoid - peritoneal shunt insertion using a conventional lumbo - peritoneal shunt and a t - tube ( medtronic neurosurgery , goleta , ca , usa ) .
after induction of general anesthesia , we turned the patient in prone position . in an attempt to explore the widest portion of syrinx , we made laminectomy at the 6th and 7th cervical levels .
following the incision of dura and arachnoid membranes , we made a small dorsal myelotomy .
the t - tube side arms , which have many holes on it , are designated long enough for a desired length .
while we inserted one side arm of t - tube into the syrinx , we placed the other side arm into the subarachnoid space .
we sutured the side arm in the subarachnoid space to the dura and surrounding ligaments .
we made the connection between the t - tube and lumbo - peritoneal shunt system .
we passed the other free side end of the lumbo - peritoneal shunt to the left flank region through subcutaneous way .
after positioning the patient in a lateral decubitus position for the second stage of the procedure , we rechanneled the shunt system to the left para - umbilical area and inserted the distal end into the peritoneal cavity using the standard shunt technique ( fig .
the global strength of the right upper extremity and whole sensory function in four extremities , especially proprioception , significantly improved .
postoperative magnetic resonance ( mr ) image one year after the surgery showed that tonsillar herniation level was the same as before the surgery ; however a significant reduction in syringomyelia size was noticed .
chiari malformation was described by han chiari in his prestigious monograph " ueber vernderungen des kleinhirns infolge von hydrocephalie des grosshirns " in 18913 ) .
he described chiari 's type i malformation as " peg - like elongation of tonsils and medial divisions of the inferior lobes of the cerebellum into cone - shaped projections , which accompany the medulla oblongata into the spinal canal"3,13 ) .
later on , he described the other variants of this malformation as type ii , iii , and iv13 ) . in 1998 , iskandar et al.10 ) defined a new type of chiari malformation as type 0 .
his mr showed a tonsillar herniation compatible with chiari type i malformation and there was also an accompanying cervico - thoracic syringomyelia .
syringomyelia is a pathological state of a longitudinal cavity extending in the vertical axis of the spinal cord1 ) .
it was first defined in 1688 by johann conrad brunner ( 1653 - 1727 ) as " a large cavity in the spinal cord extending from the fourth ventricle to the dorsal vertebrae " .
charles prosper ollivier d'angers ( 1796 - 1845 ) is the scientist who gave the name of " syringomyelia"2 ) .
different surgical treatments have been imposed for syringomyelia secondary to chiari 's malformations : cvd with or without plugging of the obex ; syringo - subarachnoid , syringo - peritoneal and theco - peritoneal shunt placement8,9 ) .
some papers found cvd effective , and some others depicted shunt procedures as effective . in a study of hida et al.9 ) , they treated 70 symptomatic syringomyelia patients with chiari type i malformation ( age range 3 - 59 years ; median , 29.4 years ) either with cvd or syringo - subarachnoid shunt placement procedure .
they preferentially treated patients with lower cranial nerve palsy or nystagmus and small syrinx cavity via cvd procedure ( 33 patients ) ; patients with large syringomyelia ( syrinx width more than 70% of the spinal cord width at the same level ) with shunt method ( 37 patients ) .
the results depicted that neurological improvement was gained in 82% of patients operated with cvd , in 97% of the patients treated with syringo - subarachnoid shunt .
syringomyelia diminished in size faster with shunt procedures ( 1.8 weeks vs. 6.3 weeks)9 ) .
complications related with shunt procedures are mainly due to technical issues such as shunt malfunction , shunt migration , arachnoiditis that leads to fibrosis around shunt tube openings , increase of tonsillar descent8,9 ) . a failure rate between 0 - 40% has been reported for cvd procedures in the literature4,7,17,19,21,23 ) .
there are some described failure reasons in cvd procedures as inadequate bone removal at the foramen magnum , residual c1 lamina , arachnoid web , suture involving obex , pseudomeningocele , intradural and/or extradural adhesion , meningitis7,9,16 ) . in our case ,
syringomyelia cavity was large and there were no lower cranial nerve palsy or nystagmus ; so we preferred a shunt procedure instead of cvd . to overcome some disadvantages of conventional syringo - subarachnoid shunt we used the new shunt system described by kim et al.11 ) , who used syringo - subarachnoid - peritoneal shunt with t - tube for treatment of syringomyelia secondary to trauma . in this technique a conventional t - tube and lumbo - peritoneal
shunt are used together . after making a small dorsal myelotomy incision at the widest level of the syrinx
, one side arm of t - tube is inserted into the cavity in rostral direction .
the other side arm is anchored into the subarachnoid space with a stich to the dura and surrounding ligaments .
t - tube is connected to the lumbo - peritoneal shunt system and the rest of the procedure is completed like in a standard shunt procedure11 ) .
after the procedure , the patient in our case got better and normalized in 6 months ' time . in the last control , 1 year after the procedure , he was still well and his control mri depicted that level of tonsillar descent was the same as before the surgery ; however the syrinx size had dramatically collapsed ( fig .
neurologically symptomatic large syringomyelia cavities secondary to chiari type i malformations should be treated surgically .
authors demonstrated the first successful application of syringo - subarachnoid - peritoneal shunt with t - tube system in a chiari type i malformation patient .
however , more clinical series with long follow - up are needed to make a general assessment of the success of this procedure in this patient population .
chiari type i malformation is a tonsillar herniation more than 3 mm from the level of foramen magnum , with or without concurrent syringomyelia . 
 different surgical treatments have been developed for syringomyelia secondary to chiari 's malformations : craniovertebral decompression with or without plugging of the obex , syringo - subarachnoid , syringo - peritoneal , and theco - peritoneal shunt placement . 
 shunt placement procedures are useful for neurologically symptomatic large - sized syrinx . in this paper , authors define the first successful treatment of a patient with syringomyelia due to chiari type i malformation using a pre - defined new technique of syringo - subarachnoid - peritoneal shunt with t - tube system .