Trigeminal neuralgia is a recurrent transient paroxysmal severe pain confined to the innervated area of the trigeminal nerve, mostly occurring in adults and the elderly, but the latest WHO survey data show that trigeminal neuralgia is becoming younger.
Currently, the main treatment modalities are medication, radiofrequency thermocoagulation, hemimelia balloon compression, stereotactic radiosurgery and microvascular decompression surgery, in addition to many other non-mainstream treatment methods are also being applied, and coupled with the differences between the levels of medical technology in different regions, many patients have not been able to receive scientific and effective treatment so far.
How to diagnose trigeminal neuralgia?
I. Diagnosis
Trigeminal neuralgia can be diagnosed based on typical clinical manifestations, and the following points are recommended for distinguishing primary trigeminal neuralgia from secondary trigeminal neuralgia.
1, electrophysiological testing of trigeminal reflexes may help to diagnose primary trigeminal neuralgia (level B evidence).
2, The presence of trigeminal hyperalgesia or bilateral simultaneous onset may be secondary trigeminal neuralgia (level B evidence), but secondary trigeminal neuralgia cannot be excluded in patients without the above features due to poor specificity.
Preoperative imaging (MRI, CT, etc.) can help to confirm the diagnosis of secondary trigeminal neuralgia (level C evidence), but for primary trigeminal neuralgia, preoperative imaging (MRI, CT, etc.) cannot confirm the diagnosis or exclude the presence of compression of the trigeminal nerve by the responsible vessels, but preoperative imaging is still recommended for patients with trigeminal neuralgia.
4. Younger age of onset, abnormal trigeminal nerve evoked potential, poor effect of medication and pain in the distribution area of the first branch of the trigeminal nerve do not suggest primary trigeminal neuralgia (level B evidence).
II. Differentiation of primary trigeminal neuralgia
Primary trigeminal neuralgia needs to be distinguished from the following diseases.
1. secondary trigeminal neuralgia.
Trigeminal neuralgia caused by tumor, aneurysm, arteriovenous malformation, etc.
2.Toothache.
Toothache mainly manifests as persistent swelling and hidden pain in the gums and face, and examination can reveal swelling of the gums, localized percussion pain and restricted mouth opening, and the pain disappears after clear diagnosis and treatment.
3.Trigeminal neuritis.
Trigeminal nerve inflammation caused by head and facial inflammation, metabolic pathology, such as diabetes, poisoning and other involvement of the trigeminal nerve, manifesting as persistent pain in the trigeminal nerve distribution area on the affected side; most of them start on one side, a few can start on both sides at the same time. Neurological examination can reveal hyperalgesia in the trigeminal nerve distribution area on the affected side, and sometimes the motor branch is also involved.
4. Glossopharyngeal neuralgia.
The pain site is mostly located in the deep facial area, tongue root, soft palate, tonsils, pharynx and external auditory canal, etc. The nature and duration of pain are similar to trigeminal neuralgia, and a few patients have “trigger points”, which are usually located in the tonsil fossa or tongue root.
5.Pterygopalatine neuralgia.
The pain can be radiated to the root of the nose, cheek, deep orbit, ear, mastoid and occipital area, etc. The pain is burning-like in nature, persistent and not obvious in regularity, and the closure of the pterygopalatine ganglion is effective.
III. Complication control
The average morbidity and mortality rate of patients with trigeminal neuralgia treated by microvascular decompression is about 0,2%, and individual reports even reach 0,5%; complications include cranial nerve injury, cerebral crest fluid leakage, cerebellar and brainstem injury, hypocranial pressure syndrome, aseptic meningitis, etc., but for medical centers that perform more microvascular decompressions every year, the occurrence of complications can be reduced.
(1) Cranial nerve dysfunction.
Cranial nerve dysfunction is mainly diplopia, hearing loss, facial palsy and facial numbness, and a few patients may develop hoarseness and choking on water. The incidence of diplopia is about 11%, which is mainly caused by the 4th and 6th pairs of cranial nerve injury, and is mostly temporary. Unilateral hearing loss is a more serious complication, caused by damage to the 8th cranial nerve pair, with an incidence of even 10%. Damage to the trigeminal nerve itself can cause facial numbness, with an incidence of 7%. Damage to the seventh cranial nerve pair can cause facial palsy, which is less common.
Intraoperative attention to the following operations can effectively reduce the occurrence of cranial nerve dysfunction.
1, try to avoid electrocoagulation cauterization of the surface of the cranial nerve and surrounding penetrating vessels, if there is small vessel bleeding, try to take compression to stop bleeding.
2.Avoid pulling the cranial nerve and reduce the direct stimulation of the cranial nerve to avoid spasm of its trophoblastic vessels.
3.To fully dissect the arachnoid membrane around the cranial nerve to achieve no intraoperative strain on the cranial nerve.
4.Routine intraoperative electrophysiological monitoring.
5.Vasodilators, hormones and neurotrophic drugs were started on the day of surgery.
(2) Cerebellar and brainstem injuries.
Cerebellar and brainstem injury, including infarction or hemorrhage, is a serious complication of microvascular decompression surgery. The key to avoid cerebellar injury is to reduce the duration and intensity of the strain. Measures such as using mannitol to reduce cranial pressure half an hour before surgery, moderate amount of hyperventilation during surgery, bone windows as close to the sigmoid sinus as possible, avoiding the use of brain pressure plates, and gradually opening the cerebellopontine pool to slowly and fully release the cerebral crest fluid before exploring the cerebellopontine angle can minimize the intraoperative strain on the cerebellar hemispheres and avoid electrocoagulation to cauterize the surface vessels of the cerebellum and brainstem as much as possible.
Postoperatively, blood pressure, pulse rate, inspiration, and oxygen saturation were monitored continuously for 24 h by a multiparameter cardiac monitor, and changes in consciousness and pupils were closely observed. If there is a sudden increase in blood pressure, a simultaneous slowing of the pulse rate, consciousness disorders after waking up, dilated pupils on one side, and a weakened or absent light reflex, cerebellar infarction, swelling, or hemorrhage should be considered, and a cranial CT scan should be performed promptly, and suboccipital decompression or extraventricular drainage with an expanded bone window should be implemented according to CT.
(3) Cerebral crest fluid leak.
Tight suturing of the dura is the key to prevent and treat cerebral crest fluid leakage. For those whose dura cannot be tightly sutured, the muscle fascia can be repaired, and at the same time, the artificial dura can be completely applied to the dura by applying bioadhesive. The open air chamber is tightly closed with bone wax. The incision is strictly closed by four layers of sutures: muscle, fascia, subcutaneous tissue and skin, leaving no dead space.
If nasal leakage of cerebral crest fluid occurs, immediately instruct the patient to lie down with the pillow removed, tell the patient not to pick, dig and block the nostrils and ear canals, keep the nostrils and ear canals clean, observe the change of body temperature, and use antibiotics to prevent infection. If necessary, use dehydrating agent or lumbar pool drainage to lower the cranial pressure. If the leaky hole does not heal for a long time or recurs several times, repair the leaky hole.
(4) Hypocranial pressure syndrome.
It may be caused by prolonged exposure of the surgical site during surgery, release of large amount of cerebral crest fluid and reduced secretion of cerebral crest fluid after surgery. It often manifests as headache, dizziness, nausea and non-jet vomiting, as well as low blood pressure and accelerated pulse rate, and the symptoms can be relieved after lowering the head position. During the operation, the dura should be filled with saline when suturing the dura to expel air and lie flat after the operation.
(5) Aseptic meningitis.
It is a more common complication and has been reported to reach 11%. At the end of surgery, the surgical area is carefully flushed with saline, and hormonal therapy can be added if necessary.