bubble_chart Overview

Intramedullary spinal cord tumors are relatively rare, accounting for about 10-15% of intraspinal tumors. They are more commonly found in the cervical and thoracic segments, with 80% being gliomas. Among these, ependymomas are the most frequent, making up approximately 55-60%, followed by astrocytomas at about 30%. Other less common types include hemangiomas, lipomas, metastatic tumors, and congenital tumors. Pathologically, these tumors mainly invade the gray matter and tend to grow vertically. When the tumor affects the spinal cord gray matter, it leads to corresponding structural damage, such as sensory disturbances or dissociated sensory loss, muscle atrophy, etc. Spinal canal obstruction occurs later compared to extramedullary tumors. Most patients with intramedullary tumors are between 20 and 40 years old, accounting for 76.5%. The duration from onset to hospital admission for surgery ranges from 2 months to 14 years, with an average of 28 months, and 70.5% of cases occur within 2 years.

bubble_chart Pathological Changes

Ependymoma

accounts for about 60% of intramedullary tumors and originates from the epithelial cells of the central canal membrane of the spinal cord, so the tumors are mostly located in the central canal region. Pathologically, they can be classified as benign or malignant (some classify them into 4 grades). Ependymomas tend to be benign because they have a pseudomembrane and can be clearly demarcated from the spinal cord. Microscopically, they exhibit a typical chrysanthemum flower-like structure, and sometimes cavities can be seen within the tumor. In contrast, ependymoblastomas are poorly differentiated, grow invasively and malignantly, and have a shorter disease course.

Astrocytoma

accounts for about 30% of intramedullary tumors and is more common in young women. It frequently occurs in the cervical and thoracic spinal segments. This type of tumor mainly consists of mature astrocytes. It grows slowly, may exhibit invasive growth, or have clear boundaries and form cysts. The tumor is soft in texture, grayish-red in color, and may show hemorrhage. Astrocytomas can be divided into two types: diffuse (or localized) fibrillary and protoplasmic. Sometimes, the cytoplasm of astrocytes expands, referred to as gemistocytic astrocytoma, with the diffuse fibrillary type being the most common. Microscopically, fibrous structures composed of glial cells are seen in the cytoplasm, interspersed with astrocyte nuclei.

Glioblastoma multiforme

, also known as polymorphic glioblastoma or simply glioblastoma, is a malignant tumor. It can rapidly invade the entire cross-section of the spinal cord. The disease progresses quickly, with a short course, averaging 5–6 months. The prognosis is poor.

Lipoma

The origin of spinal cord lipomas is unclear. Some believe they arise from embryonic remnants within the spinal cord or from ectopic tissue. The tumors are mostly located beneath the pia mater, with some growing exophytically. Those that grow invasively within the spinal cord lack clear boundaries with the spinal cord, making complete resection difficult. Decompression should be achieved through piecemeal resection. Although radical total resection is not possible, postoperative neurological symptoms can be alleviated.

bubble_chart Clinical Manifestations

Early-stage spinal cord tumors often manifest as symptoms of nerve root compression and gradually develop signs of spinal cord compression. The initial symptoms primarily include numbness, weakness, and sensory abnormalities, which are one of the characteristics of intramedullary tumors. This numbness and sensory dysfunction typically follow the distribution of natural dermatomes rather than nerve segmental planes. Concurrently or shortly thereafter, signs of irritation or compression of the long spinal cord tracts may appear. In the early stages, the tumor mainly invades the gray matter of the spinal cord, with a tendency for vertical growth, extending longitudinally along the central axis of the spinal cord. Its effect on the spinothalamic tract differs from that of extramedullary tumors (antagonism), and sensory disturbances often first arise in the segments corresponding to the lesion. As the disease progresses, symptoms gradually spread from the upper to lower regions, a unique clinical manifestation of intramedullary tumors that aids in tumor localization.

If the lesion is entirely confined to the gray matter near the central canal of the spinal cord and damages the anterior commissure where pain and temperature fibers cross, it results in decreased or lost pain and temperature sensation while touch sensation remains intact—a phenomenon known as sensory dissociation. Additionally, segmental sensory disturbances may appear during the course of the disease, closely resembling "syringomyelia." Pain symptoms emerge later and are widespread. When the tumor invades the intrinsic neurons or the crossing or descending fibers of the spinothalamic tract, pain occurs. Thus, intramedullary tumors often present with sensory loss preceding pain. This pain is characterized by its severity, fixed location, persistence, and exacerbation by coughing or exertion, but it lacks diagnostic value for localization.

Intramedullary cervical spinal cord tumors may exhibit symptoms of lower motor neuron damage, muscle atrophy, with late and mild pyramidal tract signs; hemisection syndrome of the spinal cord is rare or indistinct. In shorter disease courses, only upper limb symptoms may appear while the lower limbs remain normal. When all four limbs are affected, the upper limbs are usually more severely involved than the lower limbs, and Brown-Sequard syndrome generally does not occur. There is often reduced pain and touch sensation in all limbs, such as cold or burning sensations in the hands or feet, along with a sensory impairment level. Spinal canal obstruction appears late or is indistinct, cerebrospinal fluid protein levels are not significantly elevated, and symptoms show little improvement after CSF drainage. Spinous process tenderness is rare, and spinal bone changes are uncommon.

bubble_chart Auxiliary Examination

Spinal Canal Puncture and Cerebrospinal Fluid Examination

Spinal canal obstruction occurs late or is not obvious, and symptoms do not improve significantly after cerebrospinal fluid drainage. The increase in cerebrospinal fluid protein content is not significant.

Imaging Examination

Spinal canal contrast imaging, CT, CTM, and especially MRI are important methods for diagnosing intramedullary tumors. They can accurately determine the tumor's location, size, nature, and its relationship with adjacent tissues, providing a basis for treatment. Although spinal canal contrast imaging can show the fusiform enlargement of the spinal cord at the tumor's segment, intramedullary tumors cause spinal canal obstruction later than extramedullary tumors, making early lesions difficult to detect. CTM can more accurately display the tumor's location and nature, particularly with delayed scanning, which clearly reveals the cystic changes at the tumor's upper and lower ends.

MRI is highly important and is currently the most advanced diagnostic method for spinal cord tumors. Ependymomas on MRI often consist of solid and cystic components. The solid part is the viable portion of the tumor and the key target for surgical resection. On T1-weighted images, the signal is lower than that of adjacent normal spinal cord tissue, while on T2-weighted images, the signal is higher. Since the surrounding spinal cord edema also appears as high signal on T2-weighted images, the abnormal signal area on T2 is larger than the actual tumor size, which should be noted during surgery. Ependymomas are highly vascular tumors, and their solid parts often show significant abnormal contrast enhancement, making preoperative Gd-DTPA-enhanced scanning crucial. The cystic part results from necrosis and liquefaction, leading to secondary syringomyelia. The signal intensity of the necrotic and liquefied portion on T1- and T2-weighted images falls between that of the tumor's solid part and cerebrospinal fluid, while the secondary syringomyelia signal resembles cerebrospinal fluid. Astrocytomas on MRI appear similar to ependymomas, sometimes making differentiation difficult. Enhanced scanning has some diagnostic value: tumors with abnormal contrast enhancement located centrally in the spinal cord are more likely to be ependymomas, while those without enhancement are more likely to be astrocytomas.

bubble_chart Diagnosis

Patients with the following clinical manifestations should be considered for the possibility of intramedullary spinal cord tumors and undergo corresponding further imaging examinations:

1. Sensory dissociation characterized by numbness, weakness, and decreased or absent pain and temperature sensation while touch sensation is preserved, with sensory disturbances gradually progressing from upper to lower regions.

2. Pain symptoms appear later and are widespread.

3. May be accompanied by lower motor neuron symptoms, with Brown-Séquard syndrome being rare or不明显.

4. Spinal canal obstruction occurs late or is不明显, cerebrospinal fluid protein elevation is不明显, and symptoms show不明显 improvement after cerebrospinal fluid drainage.

5. Spinal process tenderness is rare, and vertebral bone changes are uncommon.

bubble_chart Treatment Measures

Intramedullary tumors, due to their unique location surrounded by the "fragile" spinal cord, which is difficult to recover after injury, present some disagreements in treatment choices. Some scholars advocate that tumors originating from intramedullary glial tissue should primarily be treated with radiotherapy. For instance, some authors suggest that surgery should be limited to biopsy for diagnosis, with radiotherapy being the best treatment option. However, other scholars argue that well-defined intramedullary tumors should be treated with radical surgical resection whenever possible. One author reported 11 cases of intramedullary tumors, with 9 cases completely resected, including 5 cases of astrocytoma, 3 of which were fully removed, resulting in stable or improved neurological function postoperatively. Li Youzhong et al. reported 17 cases of spinal intramedullary tumors, with 9 cases completely resected, including 7 ependymomas, 1 astrocytoma, and 1 hemangioma. Data from the General Hospital of the PLA suggest that one-stage tumor resection is a more aggressive treatment approach.

Given that ependymomas primarily grow expansively and have relatively clear boundaries with adjacent spinal cord tissue, they are the most promising type of intramedullary tumor for radical resection. Ependymomas often appear on MRI as composed of solid and cystic components. The solid part represents the viable tumor tissue and is the key target for surgical removal. Since the surrounding spinal cord edema also shows high signal intensity on T2-weighted imaging, the abnormal T2 signal area is larger than the actual tumor. Additionally, ependymomas are highly vascularized, requiring special attention during surgery.

Astrocytomas mostly grow invasively, with unclear boundaries between the tumor and adjacent tissue. Except for rare cases with pseudocapsules, complete resection is often difficult. Li Youzhong et al. reported that among 17 cases of spinal intramedullary tumors, only 1 out of 4 astrocytomas was completely resected.

The origin of spinal lipomas is unclear. These tumors are often located beneath the pia mater, with some growing exophytically and infiltrating the spinal cord without clear boundaries, making complete resection challenging. Debulking and decompression are recommended. Although radical resection is not possible, neurological symptoms can still improve postoperatively.

Vascular tumors of the spinal cord are rare, accounting for 1–3% of intramedullary tumors. They are mostly found in the thoracic and cervical regions, with the majority occurring on the dorsal side of the spinal cord. They may also coexist with cerebellar vascular tumors. Therefore, when performing MRI or CT scans of the cervical spine, the cerebellum should be included in the imaging field to detect any associated cerebellar hemangiomas. Spinal cord vascular malformations may remain asymptomatic unless complications arise.

During surgery for intramedullary tumors, meticulous and gentle handling is crucial, as even minor injury can lead to severe dysfunction below the affected segment. Key technical points to ensure surgical success include:

1. Preoperative precise estimation of the tumor's nature and extent based on clinical features, MRI, CT (CTM), and myelography.

2. Dorsal spinal cord incision: After bipolar coagulation for hemostasis at the most prominent dorsal swelling, a sharp blade is used to make a 2–3 mm incision. The tumor's solid part is usually located 1–5 mm beneath the spinal cord surface. If the tumor has a thin or pseudocapsule and is loosely connected to the spinal cord, complete resection should be attempted. For infiltrative tumors, debulking should be performed to reduce tumor volume and improve neurological function, avoiding excessive resection that could injure the spinal cord. Residual tumor tissue can be managed with radiotherapy. Microscopic surgery may be necessary, but for tumors with indistinct boundaries, complete resection is often difficult even under a microscope.

3. Careful bipolar coagulation for hemostasis to maintain a clear surgical field, aiding in tumor boundary identification and preventing postoperative adhesions. Blood vessels supplying the tumor should be coagulated close to the tumor wall, using low voltage to avoid spinal cord damage. For bleeding in the tumor bed, ice saline or diluted hydrogen peroxide-soaked cotton can be gently applied; clamping should be avoided.

4. Intramedullary tumors complicated by cystic degeneration or syringomyelia are mostly located at the upper and lower ends of the tumor. They usually contain yellow fluid rich in protein, which is presumed to be produced by the tumor tissue, and the cyst wall is formed by glial tissue. During surgery, the cystic cavity should be opened and drained into the subarachnoid space, and the cyst wall should not be resected.

5. For those with complete tumor resection, the dura mater can usually be tightly closed. Otherwise, the spinal cord should be longitudinally incised along the original length of the tumor, and the dura mater left open to fully decompress. Drainage is generally not placed to prevent cerebrospinal fluid fistula and secondary infection.

6. For tumors located in the high cervical spinal cord, special attention should be paid to the patient's respiratory dysfunction and anesthesia management during surgery.

bubble_chart Prognosis

Intramedullary spinal cord tumors are challenging to diagnose and treat due to their unique location, where even minor injury to the surrounding spinal tissue can lead to severe neurological dysfunction. Complete surgical resection is often difficult, and postoperative outcomes are frequently unsatisfactory, sometimes even worsening the condition.

bubble_chart Differentiation

cervical spondylosis

The clinical manifestations of spinal cord tumors are very similar to cervical spondylosis, and due to the high incidence of degenerative spinal diseases, spinal cord tumors are often overlooked. Clinicians should pay high attention to this. In the early stages, spinal cord tumors often manifest as radicular pain and gradually appearing symptoms of spinal cord compression. These symptoms are characterized by fixed locations, severe pain, persistent presence, and aggravation by coughing or exertion. Simultaneously or shortly thereafter, signs of stimulation or compression of the long spinal cord tracts may appear. Therefore, patients with such symptoms should routinely undergo neurological examinations and corresponding imaging studies.

Extramedullary tumors

Common clinical pathological types include neurofibromas and spinal meningiomas. Radicular pain is more common and has diagnostic value for localization. Sensory changes are more pronounced in the distal lower limbs and progress upward, without sensory dissociation. Pyramidal tract signs appear earlier and are more prominent, while lower motor neuron symptoms are less obvious. The Brown-Séquard syndrome is significantly more common. Spinal canal obstruction occurs earlier or is more pronounced, cerebrospinal fluid protein levels are significantly elevated, and symptoms worsen after cerebrospinal fluid drainage due to the downward shift of extramedullary tumors. Spinal process tenderness is common, especially in extradural tumors, and spinal bone changes are more frequently observed.

Syringomyelia

The onset is gradual. It commonly occurs in the lower cervical and upper thoracic segments of adults aged 20–30. Unilateral or bilateral multi-segmental sensory dissociation and lower motor neuron paralysis may be present. If the syrinx extends downward and invades the lateral horn cells, it is often accompanied by cervical sympathetic nerve palsy syndrome (Horner's syndrome) and upper limb skin trophic disturbances. Early stages show no spinal canal obstruction, but the advanced stage may lead to spinal canal obstruction. MRI examination can confirm the diagnosis and differentiate it from intramedullary tumors.