I. Overview.
Auditory nerve sheath tumor originates from the auditory nerve sheath and is a typical nerve sheath tumor. Since there is no involvement of the auditory nerve itself, the name auditory neuroma is inappropriate and should be called auditory nerve sheath tumor. This tumor is one of the common intracranial tumors.
It accounts for 8.43% of intracranial tumors. The peak incidence of auditory nerve sheath tumor is between 30 and 50 years old, with the youngest being 8 years old and the oldest being over 70 years old. Solitary auditory nerve sheath tumors occurring in the pediatric population are very rare. To date, all cases of auditory neuroma in children have been reported on a case-by-case basis.
The majority of swellings occur in the vestibular segment of the auditory nerve. A few occur in the cochlear region of the nerve, and as the tumor grows larger, it compresses the lateral surface of the pontine brain and the anterior border of the cerebellum, filling the pontocerebellar horn recess of the cerebellum.
Most of the tumors are unilateral, but a few are bilateral; the opposite is true when accompanied by neurofibromatosis. This tumor is a benign lesion and does not become malignant or metastasize even if it recurs many times, and if it can be removed, it can often be cured permanently. However, because the tumor is adjacent to the important brainstem, surgical resection is still a great challenge for neurosurgeons or otologists. With the improvement of neurosurgical methods and advances in neuroradiology, such as CT and MRI for early or qualitative diagnosis of tumor, brainstem auditory evoked potentials for early preoperative diagnosis, and the application of intraoperative electrophysiological monitoring and ultrasonic suction, tumors can be safely removed and the function of facial auditory nerve can be preserved.
II. Pathogenesis.
Most of the tumors originate from the vestibular part of the auditory nerve, 3/4 originate from the superior vestibular nerve, and a few from the cochlear part. The tumor originates from Schwann cells, and about 3/4 of the tumors occur in the lateral part of the internal auditory canal, and only 1/4 occur in the medial part. As the tumor grows, it can cause enlargement of the internal auditory canal, protrude into the pontocerebellar horn and fill the pontocerebellar horn. Most of the tumors are unilateral and a few are bilateral; the opposite is true if neurofibromatosis is present. The incidence of bilateral occurrence varies, but in general, the incidence of left and right side is almost equal.
III. Pathogenesis.
Auditory nerve sheath tumors cause pontocerebellar syndrome, including: dysfunction of the vestibular and cochlear parts of the nerve. The manifestations include dizziness, vertigo, tinnitus, deafness, and adjacent cranial deafness. The symptoms include dizziness, vertigo, tinnitus, deafness, irritation or paralysis of adjacent cranial nerves, balance disorders, unstable walking, and symptoms of increased intracranial pressure. However, the actual symptoms are not the same, and the symptoms can be mild or severe, which are mainly related to the starting site, growth rate, development direction, tumor size, blood supply and whether there is cystic change. At the beginning of the tumor, the vestibular part of the patient is the first to be damaged, therefore, at the early stage, there are thirty or diminished vestibular functions and irritation or partial paralysis of the cochlear nerve (early symptoms are dizziness, vertigo, tinnitus, deafness, etc.). With the growth of tumor, the anterior pole of tumor can touch the sensory root of trigeminal nerve and cause ipsilateral facial pain, facial hypesthesia, dull or loss of corneal reflex, hypesthesia of tongue tip and tongue side, if the motor root of trigeminal nerve is also affected, the patient can have ipsilateral masticatory muscle weakness, mouth opening and jaw deviation to the affected side, masticatory muscle and temporal muscle atrophy, etc.
IV. Pathology.
Auditory nerve sheath tumor has intact envelope, the surface is mostly smooth, sometimes it may be slightly nodular, its shape and size depends on the growth of the tumor, generally after the clinical diagnosis is established, its volume has mostly exceeded 2.5cm in diameter. The parenchymal part of the tumor is grayish-yellow to grayish-red in color, with a firm and brittle texture. The tumor tissue often contains cystic cavities of varying sizes, containing yellowish transparent cystic fluid and sometimes fibrin clots. The tumor adheres tightly to the cerebellar adventitia, but generally does not invade the cerebellar parenchyma and is clearly demarcated. One corner of the tumor penetrates deeply into the internal auditory canal, enlarging its opening, and the meninges here are often closely adherent to the tumor. The facial nerve is closely attached to the medial side of the tumor, and because of the large number of adhesions, it is often impossible to distinguish it with the naked eye, making surgical preservation of the facial nerve a challenge.
The histological features of auditory nerve sheath tumors can be summarized into four categories:
(1) small fenestrations of tumor cells;
(ii) intertwined fiber bundles;
(3) degenerative foci and small areas of pigmentation;
This quasi-polar arrangement of protofibers is called Antioni A tissue, while Antioni B tissue has a loose mesh-like nonpolar arrangement, which is also called mixed type. Regardless of the composition of the tumor, the interstitium of the tumor is composed of fine reticulated fibrous tissue with few collagen fibers, and often accompanied by various degenerative changes, such as fatty changes, chromatophores and small areas of hemorrhage.
V. Clinical manifestations.
Auditory neuroma is a kind of slowly developing intracranial benign tumor, the main clinical manifestations are cerebellopontocerebellar angle syndrome, including cranial nerve dysfunction dominated by vestibular nerve, cochlear nerve, trigeminal nerve and facial nerve, cerebellar damage symptoms, long conduction bundle damage symptoms and intracranial pressure increase symptoms.
1.Evolutionary process.
The emergence of clinical symptoms of auditory neuroma and its development process are influenced by many factors such as tumor starting location, development direction, tumor size and blood supply. Generally speaking, the evolution process of typical auditory neuroma symptoms has the following characteristics.
(1) Stage of vestibular nerve and cochlear nerve involvement: Since most of the auditory nerve sheath tumors originate from the vestibular nerve, the patient’s vestibular nerve is the first to be involved, and then the cochlear nerve is pushed and stimulated by the tumor to produce the corresponding symptoms. Patients experience vertigo, tinnitus, hearing loss, nausea and vomiting. Especially, tinnitus and hearing loss can last for a long time without being noticed by the patient. If patients seek medical attention for dizziness or mild tinnitus at this time, they are often misdiagnosed as otogenic vertigo or neurogenic deafness. The growth of tumor in the internal auditory canal may compress the internal auditory artery and cause ischemic lesion in the cochlea, leading to the occurrence of sudden deafness.
(2) Damaged stage of cranial nerve adjacent to the tumor: With the continuous development of the tumor, the upper part of the tumor may reach the trigeminal nerve. If the sensory roots of trigeminal nerve are stimulated, it may cause facial pain; if the sensory roots are damaged destructively, it may cause facial hypesthesia and hypoacusis or loss of corneal reflex. Involvement of the motor roots of trigeminal nerve may cause ipsilateral masticatory muscle weakness, ipsilateral masticatory muscle and glabellar muscle atrophy. As the tumor continues to develop, the abducens nerve may be affected by the tumor in some patients, and patients may experience diplopia. In the process of growth, auditory nerve sheath tumor may push and pull the facial nerve, resulting in peripheral facial palsy and loss of taste sensation in the anterior 2/3 of the ipsilateral tongue to varying degrees. If the tumor continues to develop upward, it may cause ipsilateral extraocular muscle paralysis, pupil dilatation and loss of light reflex due to the strain on the nerve. Damage to the linguopharyngeal nerve, vagus nerve and parasympathetic nerve may cause dysphagia, choking and coughing, loss of taste sensation in the posterior 1/3 of the ipsilateral tongue, soft alligator palsy, hoarseness, loss of ipsilateral pharyngeal reflex and paralysis or atrophy of sternocleidomastoid muscle and trapezius muscle.
(3) Compression stage of brainstem and cerebellar structures: the tumor can push out the brainstem when it develops medially, and when the tumor is huge, it can cause the dysfunction of the conduction bundle in the brainstem, and the patient will have different degrees of hemiparesis and hemianopsia of the contralateral limbs. Sometimes, patients may experience hemiparesis and hemianesthesia on the affected side or bilaterally. The displacement of the brainstem may cause the strain on the oculomotor nerve, resulting in unilateral or bilateral oculomotor nerve damage and eye movement disorder, eyelid ptosis, pupil dilatation and other symptoms. The prolonged compression of cerebellar peduncle and cerebellar hemispheres by tumor may lead to ipsilateral limb ataxia, inability to judge distance correctly, cerebellar dysarthria and other symptoms.
(4) Increased intracranial pressure stage: Patients will produce symptoms of increased intracranial pressure such as progressively aggravated headache, nausea, vomiting and optic papilloedema. Even some patients may suffer from secondary optic nerve atrophy due to prolonged cranial pressure increase, and even blindness in severe cases. The volume of posterior cranial fossa is small, and the compensatory ability to increase intracranial pressure is very limited. As the tumor keeps increasing, the cerebellar tonsils are pushed by the tumor and extend into the cervical spinal canal, which is in the state of chronic lower herniation, reflexively causing the patient’s neck stiffness, posterior cervical pain and discomfort and posterior occipital pain. In addition, the stimulation of local dura mater and other structures by tumor can produce local pain in suboccipital area. In the advanced stage of the disease, the patient may even have impaired consciousness and may have coracoacusis-like rigidity attack.
2. Stages of auditory neuroma development process and corresponding symptoms.
Early stage: When the diameter of tumor is <2.5cm, it is the early stage of auditory neuroma. As the tumor compresses the cochlear and vestibular branches of the auditory nerve in the internal auditory canal, the early stage is characterized by slowly occurring tinnitus, hearing loss, vertigo, gait instability and other symptoms of cochlear and vestibular dysfunction, but sudden deafness can also be seen (about %). One or more of these common early symptoms may be present, or they may occur simultaneously. The frequency and severity of symptoms vary from person to person, and may go unrecognized in mild cases to interfere with daily life due to recurrent episodes of vertigo or persistent gait instability in severe cases. Rare early symptoms include itching or tingling in the ear, numbness in the posterior wall of the external auditory canal, and reduced tearing on the affected side due to pressure on the median nerve in the internal auditory canal.
Middle and late stage symptoms: along with the increasing size of the tumor, the symptoms gradually aggravate when. If the tumor extends to the pontocerebellar angle, it may involve the trigeminal nerve and cause abnormal sensation and numbness on the affected side, and the corneal reflex may be blunted or disappear; if the tumor obstructs the cerebral crest fluid circulation, it may cause hydrocephalus and severe intracranial hypertension such as headache, nausea, vomiting and optic papilledema; if the tumor compresses the cerebellum, it may cause cerebellar dysfunction such as fine motor disorder of the affected side, unstable walking gait, etc.; if the tumor compresses the brainstem, it may cause Tumor compression on brainstem may lead to numbness and sensory loss of limbs. If the tumor enlarges to a certain degree, it may cause headache, nausea, vomiting and other symptoms due to the increase of intracranial pressure, and the patient may die due to sudden brain herniation.
Diagnosis of auditory neuroma.
Early diagnosis of small auditory neuroma is the key to strive for functional resection of the tumor. Since small auditory neuromas mainly present with cochlear and vestibular symptoms, a comprehensive and detailed otolaryngological examination is necessary to differentiate them from facial neuromas, vestibular neuritis, sudden deafness, Meniere’s disease, and other common inner ear diseases. The final diagnosis can only be confirmed by imaging of the internal auditory tract and pontocerebellar horn. Larger auditory neuromas may present with signs of V, VII, VIII cerebral nerve or posterior group cerebral nerve involvement.
A typical nerve sheath tumor has the following characteristics:
Early symptoms begin with damage to the vestibular nerve and cochlear nerve of the auditory nerve and are characterized by vertigo and progressive unilateral hearing loss with tinnitus. The first symptoms are tinnitus and deafness. The tinnitus often lasts for a short period of time, while the deafness develops slowly and can last for several years or a decade, and most of them go unnoticed by patients.
(2) The tumor adjacent to the cranial nerve damage, generally the trigeminal nerve and facial nerve damage is common, manifested as peripheral facial palsy on the affected side, or numbness of the affected side, weakness or atrophy of the occlusal muscles.
③There are also signs of unstable walking and uncoordinated movements.
④Headache, nausea and vomiting. The symptoms of increased intracranial pressure such as optic papilledema, and the manifestations of cranial nerve damage in the posterior group such as dysphagia, choking and coughing with water, hoarseness, etc.
According to the typical evolution of the patient’s condition and specific manifestations, the diagnosis is not difficult. However, the key to the problem lies in early diagnosis. It is better to make accurate diagnosis at the “otologic” stage of vestibular nerve and cochlear nerve damage or when the tumor is confined to the internal auditory canal, so as to improve the total resection rate of the tumor, reduce the risk of surgery, and preserve the function of facial and auditory nerves to the greatest extent possible.
Patients with the following symptoms should be considered for the possibility of auditory nerve sheath tumor:
(1) Intermittent onset or progressive worsening of tinnitus:
(2) Progressive hearing loss or sudden deafness.
③Dizziness or momentary unstable sensation when changing position.
④Intermittent tingling in the deep external auditory canal or deep mastoid area. Patients in the “otologic” stage often lack other neurological symptoms and signs besides tinnitus and hearing loss, and most patients go to the otologic clinic. Patients with hearing loss around middle age, without other causes such as trauma or otitis media, should consider the possibility of an auditory nerve sheath tumor. Hearing and vestibular function examination, as well as subencephalic evoked potentials and general radiological examination should be performed, and cranial CT and magnetic resonance examination should be performed if necessary to further clarify the diagnosis.
1. Audiological examination: It mainly includes pure tone audiometry, brainstem auditory evoked potentials, speech audiometry, etc. Since auditory neuroma often causes unilateral or bilateral hearing damage, the above examinations can quickly, non-invasively and effectively detect the changes and degree of hearing damage, and provide guidance for surgery and post-operative hearing reconstruction to improve the quality of life. Brainstem auditory evoked potentials or brainstem electrical response audiometry is a non-invasive electrophysiological examination, and a positive finding is a delayed or absent V wave, which is present in more than 95% of auditory nerve sheath tumors and is now widely used for the early diagnosis of this tumor.
2. Vestibular function examination: If spontaneous nystagmus to the healthy side is recorded on nystagmography, it indicates that the tumor has started to compress the brainstem and cerebellum. Nystagmus is mostly horizontal at first, but may change to vertical or oblique later. If optokinetic palsy occurs, it indicates the involvement of brainstem optokinetic pathway. A variable temperature test may show partial or complete paralysis of the affected horizontal hemianopia and may have a dominant bias toward the affected side.
3.Neurological examination: The presence of trigeminal nerve signs such as blunted or absent corneal reflex indicates that the tumor diameter is >2.5cm; the presence of cerebellar signs indicates that the tumor diameter has reached 4cm, and the above larger tumor may compress or stimulate facial nerve to cause facial palsy or facial muscle spasm and may lead to contralateral central facial palsy.
4.Imaging examination.
(1) X-ray plain film: the main changes are the indicators of abnormalities in the rock tomogram of the enlarged internal auditory canal due to bone resorption, the width of the internal auditory canal on one side is larger than the opposite side by more than 2mm; the posterior wall of the internal auditory canal is indented by more than 3mm; the bone contour of the concave edge of the medial end of the internal auditory canal disappears or is ambiguous; the sickle crest at the sieve pole level is displaced to below the midpoint of the height of the internal auditory canal.
(2) Cerebral angiography: The lesions are characterized by: the basilar artery moving toward the slope; the anterior central cerebellar vein moving backward; the pontine and anterior midbrain veins moving toward the slope; the choroid point moving backward; in larger lesions, the anterior inferior cerebellar artery is also seen to be pushed by the mass from the internal auditory tract, and the basilar artery and the pontine and anterior midbrain veins are moving backward; the basilar artery may move to the opposite side; and the tumor is colored.
(3) CT and MRI examinations: The current standard for the diagnosis of auditory nerve sheath tumor is Gd-DTDA-enhanced MRI, especially when the tumor is small (<1 cm) or within the internal auditory tract, and the CT scan is negative and the presence of tumor is highly suspected, GD-DTPA-enhanced MRI should be performed. CT can reveal the tumor is useful for estimating the degree of temporal bone pneumatization during middle cranial fossa approach and the distance between the high jugular venous bulb and the posterior semicircular canal and floor. If the patient has had CT and the tumor is large, MRI can provide information on the extent of compression of the brainstem Ⅳ whether the ventricles are patent for hydrocephalus and whether it is present For suspected auditory nerve sheath tumors or when CT is difficult to determine, full sequence MRI can make the differential diagnosis. However, attention should also be paid to possible false positives for Gd-DTPA, which is associated with inflammation of the nerves within the internal auditory tract or arachnoiditis; any small enhancing lesion near the base should be reviewed by MRI in June to assess its growth.
VII. Treatment of auditory neuroma.
There are three main options for the management of patients with auditory nerve sheath tumors: total microsurgical resection, stereotactic radiation therapy, and follow-up observation. Younger patients with confirmed growing tumors may opt for surgery; older patients aged 70 years and above, without obvious symptoms and with imaging data showing no tumor enlargement, should be regularly observed and followed up with imaging. In most countries, the most common surgical approach for patients requiring surgical treatment according to the above principles is the suboccipital approach, followed by the transfemoral approach. Neurosurgeons tend to prefer the former, while neuro-otologists tend to prefer the latter.
1. Surgical treatment.
If a patient has a definite vestibular nerve sheath tumor by MRI, surgical total excision of the tumor is an effective treatment. Early surgical treatment of small vestibular nerve sheath tumors (less than 3 cm in diameter) can preserve 30-65% of the patient’s useful hearing and 75-92% of the normal function of the facial nerve. Even when hearing is lost, early tumor removal may help preserve the integrity of the cochlear nerve, allowing the patient to regain hearing with a cochlear implant. However, when the tumor increases in size beyond 2-3 cm, the surgical risks (e.g., facial palsy, posterior group cranial nerve injury) increase as the tumor grows.
Currently, the traditional treatment strategy in China is usually conservative: for tumors of 2-3 cm in size, surgery is only recommended when hearing is already lost or when the tumor is growing rapidly; while when the tumor grows beyond the 2-3 cm range, the surgical risks (e.g., facial palsy, posterior group cranial nerve damage) will increase as the tumor grows. Some patients who want to insist on preserving their hearing, although understanding that this wait-and-see approach will eventually lead to serious complications from surgery (including facial palsy and inevitable hearing loss), still choose to wait until symptoms of brainstem compression or high intracranial pressure necessitate surgical removal of the tumor.
Surgery requires consideration of a number of medical risk factors and concomitant medical conditions, such as congestive heart failure and uremia. The presence of hydrocephalus affects the management of auditory nerve sheath tumors in several ways. Elderly patients with symptomatic hydrocephalus require shunting, and the decision to remove the tumor or not is then based on its response to the shunt. If the tumor is no longer growing, treatment of hydrocephalus may be sufficient. In contrast, in young patients with hydrocephalus and growing tumors, both hydrocephalus and tumor should be treated. As described below, in patients with tumors larger than 2 cm, if the contralateral hearing is lost due to a condition such as otitis media rather than to an auditory nerve sheath tumor, microsurgical removal should be performed after further tumor growth has been determined. For such patients, stereotactic radiation therapy may be considered in order to preserve hearing for a longer period of time after surgery. Conversely, in patients with tumors smaller than 2 cm, microdissection should be considered because of the greater likelihood of postoperative hearing preservation. In patients with bilateral auditory nerve sheath tumors (NF2), because of the need to preserve hearing, their management options and surgical maneuvers require special consideration. Unfortunately, regardless of microsurgery or stereotactic radiation therapy, the risk of postoperative hearing loss is higher in patients with NF2 than in patients with unilateral tumors.
2. Stereotactic radiotherapy.
To avoid the risk of surgery without delaying treatment, patients can also choose stereotactic radiation therapy (gamma-knife, etc.). Or for most of the postoperative residual tumors, radiation therapy can be chosen. It is generally believed that with this local radiation, the tumor can be controlled in a stable volume and some of the tumors can be necrocystic and thus decrease in size. It is a better choice for patients who do not want to undergo surgery. However, long-term stereotactic radiation therapy requires continuous local irradiation and some tumors may induce malignant lesions, so it remains to be further proven as the preferred treatment option for auditory nerve sheath tumors.
If a patient has an auditory neuroma, should surgery or gamma-knife (Gamma Knife) treatment be chosen?
Surgical total excision of the tumor is an effective treatment method. Early surgical treatment of small vestibular nerve sheath tumors (less than 3 cm in diameter) is currently advocated overseas and can preserve 30-65% of the patient’s useful hearing and 75-92% of the normal function of the facial nerve. When large tumors (more than 3 cm) are present, the surgical risk will increase with the size of the tumor. Postoperatively, patients may have associated complications, including patient facial paralysis or hearing loss.
In contrast, gamma-knife treatment with local radiation can mostly be controlled to a stable volume for smaller tumors (less than 3 cm in diameter) and preserve 33-57% and 92-100% of the patient’s modest hearing and normal function of the facial nerve. However, radiation therapy requires multiple local irradiation, and there is a risk of inducing malignant disease after radiation. In addition, the scarring caused by long-term radiation therapy increases the difficulty of future surgical excision to preserve facial nerve function, and creates difficulties for further hearing reconstruction due to the impact on vestibular snail nerve function and activity.
Patients should choose the suitable treatment plan according to the actual situation.
3. Hearing reconstruction techniques.
Since 90C95 % of NF2 patients will have bilateral vestibular nerve sheath tumors, resulting in bilateral hearing loss. Therefore, hearing reconstruction should be performed to improve the patient’s hearing and quality of life. Cochlear implantation (CI) is an option to permanently improve hearing when the patient has bilateral hearing loss but has an anatomically and physiologically intact cochlear nerve. When the physiological integrity of the cochlear nerve is destroyed, auditory brainstem implantation (ABI) can be a better option for their hearing reconstruction.
VIII. Pre- and post-surgical care for auditory neuroma.
1.Pre-operative preparation.
Patients should assist the doctor to do the preoperative examinations, and their families should give them a high-calorie, high-protein, high-vitamin, and easy-to-digest diet before surgery to replenish their internal consumption, increase their body resistance, improve their tolerance to surgery, and promote the healing of the incision as soon as possible after surgery. For patients with increased intracranial pressure, they should be instructed to reduce their activities and rest in bed.
2. Postoperative care.
Posture is important for postoperative patients, and slight negligence will bring irreparable damage to the patient. Specific practices are as follows.
(1) When moving the patient after surgery, the movement must be gentle and smooth, and one person should hold the patient’s head with both hands to prevent the head and neck from twisting or shaking.
(2) Take a flat position when the patient is not awake from general anesthesia, with the head tilted to the healthy side and a cold water bag on the head to reduce and prevent intracranial hemorrhage. After the patient is awake and blood pressure is stable, the head of the bed should be elevated 15°~30°, which is conducive to intracranial venous reflux, reduce cerebral edema and lower intracranial pressure.
(3) If the tumor volume is large and there is a large space in the cranial cavity after surgery, the patient should be placed in the healthy side. Head turning is prohibited within 24 h after surgery to prevent sudden displacement of brainstem which may cause whistling and cardiac arrest, but head movement should be very careful after 24 h. Even several days after surgery, head turning should be very light and slow, and attention should be paid to keep head and body turning at the same time.
3. Complication care.
(1) Hearing loss: It is related to the tumor compressing the auditory nerve, so the patient’s family should talk patiently with the patient, understand the patient’s needs, meet the patient’s requirements in life, and answer the questions until the patient understands, supplemented with gestures and words if necessary, to enhance the patient’s confidence to overcome the disease.
(2) Facial nerve injury: Facial nerve injury is one of the main complications of post-operative auditory neuroma. Patients with incomplete or completely unclosed eyelids are prone to corneal ulcers and even blindness, so family members should give chloramphenicol eye drops and apply gentamycin eye ointment, wear eye shields for protection during the day, and sleep at night covered with petroleum jelly gauze for dust and moisturizing. Patients with loss of facial sensation should prevent burns when eating, prohibit hot and cold compresses on the affected face, and prohibit the application of irritating drugs. For patients with crooked mouth, massage the affected face for 1 week after surgery, and patients should often do actions such as opening mouth, cheek puffing, blowing, etc., and cooperate with acupuncture treatment can make the condition relieved.
(3) Risk of brainstem displacement: After tumor removal, the local cavity is formed and the brain tissue cannot be reset quickly, so excessive moving of the head may make the brainstem move to the surgical cavity and cause whistling arrest. After 24 hours postoperatively, family members should not move the head excessively when turning the patient, pay attention to the simultaneous turning of the head and body, avoid sudden turning of the neck to the healthy side, observe the changes of whistling, pulse, blood pressure and pupil after turning, and report to the doctor in time if shortness of breath is found.
(4) Posterior group cranial nerve injury: postoperative auditory neuroma, especially larger auditory neuroma, is often accompanied by posterior group cranial nerve injury, and patients will experience hoarseness, choking, difficulty in swallowing, weak cough, and difficulty in active sputum evacuation, which can easily cause obstruction of the whistle and pulmonary complications. At this time, we should listen to the requirements of doctors and nurses, provide dietary guidance and strengthen the care of the whistle tract, try to feed water after 3 d of postoperative fasting, and then give liquid food if Yuan chokes and coughs, and then gradually give semi-liquid food, and give high protein, high vitamin, high calorie, easily digestible nasal fluid diet to those who have choking and cough, and give universal food after 2 weeks according to the recovery of patients.