Introduction
Surgical treatment of primary trigeminal neuralgia is one of the most successful cures ever achieved in neurosurgery. Semilunar and post-trigeminal ganglion trigeminal neurotomy was already in medical practice 90 years ago, well before the use of phenytoin in 1942 and carbamazepine in 1963 for trigeminal neuralgia.
Percutaneous access to the trigeminal system was popularized by Hartel, who in 1914 described in detail the technique of puncture with external markers. in 1932 Kirschner described the method of percutaneous ganglion thermocoagulation. In 1965 Sweet introduced a method that included local intermittent anesthesia and controlled high-frequency disruption. 1981 Hakanson discovered that percutaneous glycerol nerve root disruption could treat TN. 1983 Mullan and Lichtor invented balloon compression of the trigeminal ganglion.
Radiation therapy was originally invented by Lars Leksell in 1951. After 20 years of accumulation and precipitation, gamma knife radiation therapy has become a commonly used method to treat TN nowadays. In addition to the above techniques of open, percutaneous or radiotherapy, after Dandy first discovered that the adjacent artery compressed the trigeminal nerve root causing trigeminal neuralgia in 1934, apparent microvascular decompression gradually developed. The first decompression of the responsible vessels was done by Gardner in 1959, but the real improvement in the surgical approach was done by Jannetta in 1967 with microscopic decompression of the apparent microvessels.
Diagnosis of trigeminal neuralgia
The diagnosis of typical trigeminal neuralgia is based on the clinical presentation, which presents as
confined to one side of the face
Within the innervation of the trigeminal nerve
Sudden electric shock-like pain that is painless during the interictal period At least in the early stages of the disease
Pain can be spontaneous, but is more often triggered by stimulation
No sensory disturbances, normal corneal reflexes, and no other cranial nerve symptoms
Anticonvulsant medications are effective, at least early on
After some time the pain becomes more frequent, with shorter intervals, a soreness or burning sensation, and sometimes a vasodilatation phenomenon that makes the neuralgia less typical.
TN can be diagnosed as primary trigeminal neuralgia after ruling out other specific causes. Ruling out the diagnosis requires appropriate methods, especially standard MRI.
Neurovascular compression can be confirmed by appropriate MRI sequences, and the following three are particularly useful.
3D-T2-High-resolution sequences provide clear neural and vascular structures in the pontocerebellar horn pool, but cannot distinguish vessels from nerves
3D-TOF (time-of-flight)-angio sequences can distinguish vessels, especially those with faster flow rates, such as arteries.
3D-T1-contrast sequence can show the injected vessels well, and veins are visualized as well as arteries.
The above three sequences must be performed.
Indications for surgery
Conclusion
Surgery is generally considered to be an option in cases where anticonvulsant drugs are ineffective or medication is not tolerated, and medication intolerance includes weakness and sleepiness.
Microvascular decompression is the etiologic and traditional treatment and should be the surgical option of choice for patients in good general condition. mvd can cure 75% of trigeminal neuralgia due to vascular compression, 90% of preoperative MRI-determined vascular compression, and most patients have no adverse effects. Vascular compression and nerve root deformation can be confirmed with the aid of new MRI, although sometimes not reliably. Hearing can be protected by stopping the procedure when the posterior curtain of the ethmoid sinus is in place.