Shajehan S, Fazal Gafoor PA, Krishna Kiran, Usha R Experience with fascia lata graft for Micro-Vascular Decompression for Trigeminal neuralgia and Hemi-facial spasm.The Calicut Medical Journal

Experience with fascia lata graft for Micro-Vascular Decompression for Trigeminal neuralgia and Hemi-facial spasm

Shajehan S, Fazal Gafoor PA, Krishna Kiran, Usha R
Dept of Neurosciences and Dept of Radiology,
National Hospital,Calicut, Kerala, India .

Address for Correspondence:
Dr Shajehan S
Dept of Neurosciences and Dept of Radiology,
National Hospital, I. G. Road,
Calicut, Kerala, India 673001.
E-Mail:shajeus@snacharnet.in

The efficacy of Micro-Vascular Decompression (MVD) as a treatment modality for Trigeminal Neuralgia and Hemi-facial spasm and other cranial nerve compression syndromes of the posterior cranial fossa is well established. Various types of implants have been used during MVD to keep the offending vessel away from the nerve. We have used fascia lata in a series of 10 patients who underwent MVD over a period of 2 years. Graft related complications like aseptic meningitis, slipping of the graft with resultant recurrence of neuralgia etc., were not encountered in these patients. All patients had excellent relief of symptoms. The vascular anomalies encountered, the procedure, the results and the advantages of using fascia lata as graft are discussed.

The clinical manifestations of neuro-vascular compression syndromes of the posterior fossa are manifold. Trigeminal neuralgia, hemi-facial spasm, glossopharyngeal neuralgia, intractable vertigo, tinnitus and essential hypertension have neurovascular compression as an etiology (1, 2, 3, 4, 8). Though they initially respond to medical treatment a lot of these patients go on to develop intractable symptoms that can be relieved by surgical treatment viz., MVD. Vascular compression of cranial nerves in the posterior fossa due to arterial loops or stretched veins results in segmental demyelination at the point of contact between the vessel and the nerve. The resultant changes in the nerve leads to ephaptic transmission or "cross talk" within the fibres of the nerve causing neuralgic pain or hemi-facial spasm (5). Similar compression of the lateral medulla on the left side leads to essential hypertension (6). Surgical exposure and separating the offending vessel off the nerve and keeping the vessel away from the nerve using an interposed graft relieves the neural compression and the symptoms (7, 8, 9). Various types of implants have been used during MVD as the graft including fat, muscle, Teflon, Dacron, gelfoam etc. We have used fascia lata as the interposition graft during MVD for trigeminal neuralgia and hemi-facial spasm and obtained excellent results.

From July 2000 to June 2002 we have operated on 10 patients, 2 of whom had hemi-facial spasm, 7 had trigeminal neuralgia and 1 had Tic convulsif (trigeminal neuralgia with ipsilateral hemi-facial spasm). The mean duration of symptoms was 8 years in the patients with trigeminal neuralgia. They had distressing symptoms in spite of being on continuous medication. One patient had partial relief of pain for 6 months following a Glycerol injection of the trigeminal ganglion 3 years earlier. The youngest patient was 35 years old and the oldest was 70.
Both patients with hemi-facial spasm were women in the 6th decade with worsening symptoms of more than 3 years duration and had no relief with medication. The patient with Tic convulsif was a 65 year old lady with trigeminal neuralgia and hemi-facial spasm on the left side. She and a 70 yr old male with trigeminal neuralgia on left side had medically intractable hypertension. None of the patients had other medical problems. Two of the patients with trigeminal neuralgia, 1 with hemi-facial spasm and the lone patient with Tic convulsif had hyper-cholesterolemia on biochemical evaluation.
MRI of the brain was done in all the patients to rule out a mass lesion in the posterior fossa, requesting the radiologist to look out for a vascular compression. With 1 mm thin slices through the posterior fossa it was possible to demonstrate the neurovascular compression in all the 10 patients (10, 11, 13). One patient with trigeminal neuralgia and the patient with Tic convulsif had a dolicho-ectactic vertebro-basilar system.

All patients underwent a Retro-mastoid craniectomy in the lateral position. A lumbar drain was inserted at the beginning of the surgery in all the patients to drain CSF and to facilitate cerebellar retraction. After opening the dura the cerebellum was gently retracted superiorly or laterally as the case may be, for trigeminal neuralgia or hemi-facial spasm to visualise the appropriate cranial nerve. The superior petrosal vein was divided in all patients with trigeminal neuralgia. Arachnoidal dissection and separation of the offending vessel from the nerve was done followed by the placement of an appropriate sized fascia lata graft between them. In one case of hemi-facial spasm the graft was wrapped around the 7th nerve as the Anterior inferior cerebellar artery (AICA) had made a groove around it.

The Superior cerebellar artery (SCA) was found to be compressing the nerve in 5 cases of trigeminal neuralgia. In one case the 5th nerve was seen to be compressed superiorly by the SCA and inferiorly by the AICA. One case each was due to neural compression by the superior petrosal vein and an ectactic basilar artery. The SCA was found to be duplicated in 2 patients and triplicated in 2 patients. The patient with Tic convulsif had a dolicho-ectactic basilar system pressing on both the 5th and the 7th nerves (9, 12, 14). Atheromatous plaques could seen through the vessel wall in the patient with Tic convulsif. One case of hemi-facial spasm had a loop of the AICA tightly encircling the nerve with a groove seen around the nerve. The other patient with hemi-facial spasm had a loop of the AICA going into the internal auditory meatus and coming out. Both patients with hemi-facaial spasm required the sub arcuate artery to be divided, preserving the internal auditory artery before the loop of the AICA could be mobilised and separated off the nerve. These operative findings concur with the data in various other operative series by Peter Jannetta, Marc P Sindou, Albert Rhoton Jr., Tetsuo Kanno, Gardner, AK Singh, KE Turel etc., (9).


I: 5th nerve compression superiorly by duplicated SCA and inferiorly by AICA, grooving the nerve.	II: AICA loop entering and exiting IAM on either side of the 7th-8th complex.

III: Extricated AICA loop and the 7th nerve showing areas of compression on both sides.	IV: Fascia lata graft covering the 7th-8th complex with the AICA loop lying separate.

All the patients with trigeminal neuralgia had complete relief of neuralgic pain after surgery. One patient with hemi-facial spasm became asymptomatic early in the post-operative phase and the other patient had occasional twitches for another 2 weeks before becoming totally free of her symptoms. The medically intractable hypertension which 2 patients had pre-operatively came under control after MVD and their anti-hypertensive drugs could be reduced.
Two patients had post-operative vomiting which responded to Ondensetron. Both patients with hemi-facial spasm had transient tinnitus which subsided spontaneously over a period of 3 weeks. One patient had a facial paresis which recovered in a week's time. The patient with Tic convulsif developed headache and nausea 3 months post operatively, and CT scan revealed communicating hydrocephalus. She became asymptomatic after a Ventriculo-peritoneal shunt. There was no incidence of aseptic meningitis in these patients, which however, is reported in up to 20% of patients where Teflon felt or Dacron was used as the graft (9). There is no recurrence of symptoms in any of these patients and they are on regular follow-up. Recurrence of symptoms has been reported in 3-5% in patients due to graft getting displaced or disappearing over a course of time (9, 15). Synthetic grafts may migrate into the sub-arachnoid space and fat or muscle may disappear over time. Post-operative MRI scan in our patients after 1 year has demonstrated persistence of the graft at the implant site.

Fascia lata had excellent handling properties per operatively. It could be positioned between the vessel and the nerve with ease and in 4 patients it was possible to even wrap the fascia around the nerve without difficulty using micro instruments. Thus, fascia lata was found to be a good graft material. Being autologous tissue and the fact that it could be obtained sterile during the procedure by a small incision on the lateral aspect of the thigh also makes it an excellent choice as a graft for MVD.
Gentle cerebellar retraction facilitated by introduction of a lumbar drain at the beginning of surgery, careful and minimal handing of the nerves, and minimal use of bipolar coagulation helped in achieving a good out come.

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