The submicrocephalic tonsillar herniation malformation, also known as Arnold-Chiari malformation, is mainly due to congenital anomalies of the posterior cranial fossa structures and manifests as a wedge-shaped herniation of the cerebellar tonsils below the foramen magnum. Depending on the severity, it may be accompanied by displacement of the lower part of the medulla oblongata and the lower part of the fourth ventricle into the cervical spinal canal, resulting in the displacement of the linguopharyngeal, vagus, and paramedian nerves and the spinal nerves at the high cervical end by pulling. In severe cases, the subarachnoid space is blocked and the cerebrospinal fluid circulation is obstructed, resulting in hydrocephalus.
Clinical symptoms.
1, the medulla oblongata and high cervical medulla compression manifestation, limb sensory numbness and weakness, walking instability, urinary and fecal disorders, tightness of the chest, etc.
2. Posterior group cranial nerve and high cervical nerve root compression, manifested as hoarseness, choking and coughing, occipital and cervical pain, and limitation of neck movement.
3, cerebellar compression symptoms, walking unsteadiness like drunkenness.
4. Hydrocephalus, headache, vomiting, etc.
Clinical examination.
Subungual herniation malformation of the cerebellum can often be clarified by craniocervical junction area MRI, but a cranial MRI is also needed to rule out hydrocephalus, and depending on the patient’s specific situation, somatosensory evoked potentials and electromyography may also be required.
Treatment modalities.
1, internal medicine treatment, internal conservative treatment (including Chinese medicine, traditional Chinese medicine and acupuncture and other treatments) can not relieve the clinical symptoms of patients, and even further aggravation of symptoms.
Surgery is mainly for patients with progressive exacerbation. The incision is small (about 5-175 px long) and requires removal of a portion of the occipital bone, cutting open the dura mater outside the cerebellum, and repairing it with artificial fascia.
Typical cases
Case 1
Female patient, 14 years old, student.
She complained of cervical pain with progressive muscle atrophy and weakness in both hands for 2 years.
MRI of the craniocervical junction showed: bilateral submicrocephalic tonsillar herniation 30px below the foramen magnum, disappearance of the subarachnoid space in the craniocervical junction, and cervical spinal cord cavity formation.
Preoperative diagnosis: submural herniation of the cerebellar tonsils and spinal cavity.
The patient had been treated with acupuncture and moxibustion in an outside hospital and was ineffective in taking oral Chinese medicine and other drugs.
Operation name: Suboccipital posterior median approach – posterior cranial fossa decompression and dural expansion repair.
The position and incision: left lateral position (the head frame can firmly fix the head and can make the neck retracted), the length of incision is about 150px, about four transverse fingers.
The patient’s neck pain disappeared and the strength of the hands improved after the three-month review.
Postoperative MRI of the craniocervical junction showed retraction of the inferior herniated cerebellar tonsils, increased space in the posterior cranial fossa, and a significantly smaller spinal cord cavity than before surgery.
Case 2
Female patient, 49 years old, with neck pain for 1 year and numbness in the limbs for 1 month.
On examination: pain and hyperalgesia in both upper limbs and muscle atrophy in both upper limbs.
Preoperative MRI showed a wedge-shaped herniation of the cerebellar tonsils into the cervical spinal canal and a significant spinal cord cavity.
Postoperative MRI of the craniocervical junction showed retraction of the lower herniated cerebellar tonsils, an increase in the space of the posterior cranial fossa, and a significant reduction of the spinal cord cavity compared with that before surgery.