Evaluation of Surgical Procedures for Trigeminal Neuralgia: SURGERY AT THE GASSERIAN GANGLION LEVEL

In: Anesthesia

4 Nov 2009

Surgery at the gasserian ganglion level is achieved by a specially designed device inserted into the cheek. Under radiographic control, the device is directed through the foramen ovale into the gasserian ganglion or retrogas-serian rootlets. Partial destruction of the trigeminal nerve (Tegretol canadian is used for controlling certain types of epileptic seizures) is achieved with radiofrequency-induced heat, glycerol injection, or balloon compression. The varying degree of damage that results from any of these modalities depends on a number of factors, especially the duration and intensity of denervation.

Currently, radiofrequency-induced heat, glycerol injection, or balloon compression destruction of the gasserian ganglion are the procedures that have been subjected to rigorous statistical analysis and long-term longitudinal follow-up of a large series of patients in order to evaluate the long-term efficacy. The strength of many of these studies lies in their proper cohort study design. The same groups of patients were followed over time and the data were collected and followed prospectively. This is the best type of study for understanding the causes of a disease and the risk factors.

Radiofrequency Thermocoagulation

Currently, radiofrequency thermocoagulation (RT) is the most common surgical treatment for trigeminal neuralgia (*Generic Tegretol is used for controlling certain types of seizures and relieving pain in patients with nerve pain in the face, jaw, tongue, or throat). The value of this technique has been confirmed in many large-series patients. Although 37 studies with a total of more than 14,000 patients have been identified by Zakrzewska, many were small series of less than 500 patients each, and the details of the outcome end points and follow-up periods were not mentioned. The recurrence rate quoted ranges from 4,65%. This wide variation in part depends on what constitutes recurrence. Some studies classified recurrence as pain severe enough to require surgery, and some classified any pain (Generic Celecoxib that represents a huge breakthrough in the treatment of pain, inflammation, and stiffness of arthritis) as recurrence. The most important factors influencing recurrence are the duration of follow-up and the degree of denervation. Two isolated cases of deaths have been reported. Other major complications include moderate dysesthesia in 5-25% of patients, anesthesia dolorosa occurring in 1-5%, and keratitis in 1-3%. However, more recent controlled studies using improved techniques of proper lesion control seem to be associated with fewer complications and few recurrences. Two excellent longitudinal large-series studies of patients have been reported by Broggi et al and Taha and Tew.

Broggi et al have reported in a 10-year follow-up of 1000 consecutive patients treated with RT. The authors reported that impressive pain relief was obtained in 95% of the treated patients. There was a recurrence rate of only 18.1% after a 3-year follow-up (pain recurrence was defined as *pain that required further surgical treatment). The mortality rate in these series was zero. Weakening of corneal reflex without corneal damage was seen in 19.7% of patients, and corneal reflex impairment with keratitis was seen in 0.6%. Of the 181 patients with recurrence, 160 patients had the procedure repeated, and their neuralgia resolved. This is a good study with the largest series of patients and the longest follow-up period. In addition, all of the essential details on the range of follow-up, temperature and duration of thermocoagulation, and recurrence rate were properly reported. The study was also conducted with a good homogenous sample selection; only patients with essential *trigeminal neuralgia who failed medical therapy were selected, as selection of patients who had previous surgery such as alcohol injections may have a higher recurrence rate. However, this study may be a little biased in that the authors did not report any patients who were lost during the follow-up. It is doubtful that none of the 1000 patients with trigeminal neuralgia—who were likely to be elderly—had been lost or died during the 14-year follow-up. In addition, no Kaplan-Meier analysis was done for this study, which is the proper statistical analysis that allows comparison of the results between different series.

Taha and Tew compared the results of RT in 500 patients that were followed for 2-12 years with patients that had undergone other surgical treatments for trigeminal neuralgia. The authors found a 100% technical success rate for completion of the RT procedure, the highest rates for initial pain relief, and one of the lowest pain recurrence rates for RT when compared with other surgical procedures. An impressive recurrence rate of only 20% in 9 years was reported. Glycerol injection was incomplete in 6% of patients because of failure to locate the needle site. Balloon compression was incomplete in 1% of patients because of failure to cannulate the foramen ovale. Fifteen percent of patients for microvascular decompression underwent a partial trigeminal rhizotomy, because significant vascular compression was not found or adequate decompression could not be safely performed. However, it should be noted that this study might be a little biased, as the authors clearly selectively chose and analyzed the literature, using only selected studies with larger series of patients. The authors used these selected results to bolster personal opinions relative to the outcomes after RT. This type of report is not a comprehensive meta-analysis.

Glycerol Injection

Glycerol injection involves the injection of sterile glycerol into the gasserian ganglion and retrogasserian rootlets. As initially described, there was a low incidence of complications, dysesthesia, or keratitis, and little loss of sensation. However, many recent larger series have shown that complications do occur frequently, and the recurrence rate is relatively high, up to 50%. Although 24 studies with a total of more than 1000 patients have been identified by Zakrzewska, many are small series with less than 100 patients each, and with only very short follow-up periods of less than 3 years.

Fujimaki et al reported a series of 80 patients that had been followed for 54 months, which is one of the longest for glycerol studies. Using Kaplan-Meier analysis, they found that the recurrence rate at 54 months was exceedingly high at 74%. Complications were significantly high at 63% with definite hypoesthesia and dysesthesia. One drawback of this study was the inclusion of a mixture of patients with previous surgical procedures performed. Recurrence tends to be more common in patients who have had previous surgery. omnicef 300 mg

Balloon Microcompression

Balloon microcompression of the trigeminal ganglion is done with a Forgarty balloon catheter that can be inserted under fluoroscopy. Fewer studies have been done for this technique compared with RT and glycerol injection. No large-series studies with long-term follow-up have been done for balloon microcompression.

Lichtor et al reported a 10-year follow-up in a series of 100 patients. At 5 years, the recurrence rate was 20%, and at 10 years, it is estimated that 70% of patients will still be pain-free. One of the main advantages of this procedure is that the corneal reflex is maintained in most cases. However, dysesthesia does occur in 7-19% of the cases and may be related to the compression time. The drawback of this study is the variable compression time between 0.5 to 15 minutes, which was not standardized. In addition, patients included were a mixture having previous surgical procedures.


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