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Tumors of the Conus and Cauda Equina

  • Author: James S Harrop, MD; Chief Editor: Brian H Kopell, MD  more...
 
Updated: Apr 30, 2016
 

Overview

The spinal cord transmits information between the spinal cord and brain to the nerves and muscles. The distal or terminal portion of the spinal cord is also referred to as the conus medullaris.

In adults, the spinal cord terminates at approximately the level of L1. This space is created by the differential growth of the vertebral column compared with the spinal cord, which causes the spinal cord to ascend with growth. The nerve roots then descend through this fluid sac containing cerebrospinal fluid and are referred to as the cauda equina ("tail of a horse"). This is the collection of lumbar and sacral spinal nerve roots that course in a caudal direction to emerge from their respective foramina.

Compression of the spinal cord and nerve roots by tumors of the cauda equina and the conus medullaris produces pain and progressive deterioration of neurologic function, including motor weakness, sensory deficits, and bowel and bladder dysfunction. These symptoms are collectively known as the cauda equina syndrome.

The general classification of tumors of the cauda equina and the conus medullaris is according to the tissue compartment in which the tumors are located. This classification is based on their relationship to the meninges that enclose the central nervous system, as follows:

  • Extradural tumors - Arise outside the spinal cord and the meninges and the epidural tissue
  • Intradural-extramedullary tumors - Arise inside the dural sac, from the leptomeninges or the nerve root, outside the substance of the spinal cord parenchyma
  • Intramedullary tumors - Arise within the substance of the spinal cord

Tumors, disk herniations, fractures, and infection (ie epidural abscesses) are all possible causes of cauda equina syndrome. Determining the precise nature of the lesion (eg, intradural-extramedullary vs intramedullary) and the exact type of tumor (eg, ependymoma vs astrocytoma) based on clinical findings can be difficult.

The ability to noninvasively image the neural elements with magnetic resonance imaging (MRI) for evolving neurological deficits in addition to chronic conditions such as low back pain has facilitated the diagnosis of this disorder. See the image below.

Tumor of the conus medullaris. Tumor of the conus medullaris.

The treatment for tumors of the cauda equina or conus medullaris is primarily surgical resection. Radiation therapy and intrathecal chemotherapy are reasonable adjuvants for the treatment of these tumors in patients with contraindications for surgical treatment.

Go to Cauda Equina and Conus Medullaris Syndromes and Neurosurgery for Cauda Equina Syndrome for complete information on these topics.

Historical background

In 1887, Sir Victor Horsley performed the first successful removal of a spinal cord tumor, an extramedullary-intradural fibromyxoma that was compressing the spinal cord. The patient subsequently regained gait function.

In 1907, Eiselsberg-Renzi first successfully removed an intradural intramedullary tumor. However, in 1905, Cushing reported the first attempted surgical resection of an intramedullary spinal neoplasm. In 1925, Charles Elsberg published the first large series of patients that underwent a resection of spinal cord neoplasms. Unfortunately, these patients endured significant associated morbidity and mortality related to operative techniques during this period.

In 1963, Greenwood reported a modern series on removal of intramedullary tumors with good success.[1] The conclusion was reached that because of the relatively direct surgical approach to the lumbar spinal canal, tumors in that area are amenable to successful surgical resection.

Patient education

For patient education information, see the Back, Ribs, Neck, and Head Center; Cancer and Tumors Center; and Brain and Nervous System Center, as well as Back Pain, Lumbar Laminectomy, and Cauda Equina Syndrome.

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Anatomy

Nerve fibers descend from and ascend to the brain to and from the peripheral nerves. The distal spinal cord terminates as the conus medullaris, and it contains the sacral cord and the vestigial coccygeal cord. The nerve roots form the cauda equina, the collection of nerve roots distal to the conus that supply the lower part of the body. The conus typically terminates at the L1-2 level.

Extending distally from the conus medullaris is a delicate filament, the filum terminale. The first 15 cm are contained within the dural sac, the filum terminale internum. The filum terminale consists of fibrous tissue that is continuous with the pia mater.

The central canal of the spinal cord continues down into the filum terminale for the first 5-6 cm, an area that also contains neural and ependymal cells. The extension beyond the apex of the dural sac is the filum terminale externum, which extends to attach to the first coccygeal vertebra. The filum terminale externum actually has a closely adherent dural layer around it.

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Epidemiology

Tumors of the spinal cord are rare and reported to represent approximately 10-15% of all central nervous system tumors. Overall, they represent an estimated incidence of 0.5-2.5 cases per 100,000 population. Extradural spinal cord tumors constitute by far the greatest majority of spinal tumors and include metastatic tumors. Intradural extramedullary tumors account for approximately 20% of all spinal tumors, with intradural-intramedullary tumors accounting for less than 5% of all spinal tumors.

Ependymomas

In the adult population, ependymomas (intradural-intramedullary) are the most common intra-axial tumors of the conus medullaris and filum terminale. They comprise more than one third of the tumors in the region. Ependymomas represent approximately 60% of all glial neoplasms of the entire spinal cord and are the most common glial neoplasm below the midthoracic region.

Conus medullaris tumors are diagnosed in the third to fourth decade of life, with a slight male predominance. A variant of ependymomas, myxopapillary ependymomas tend to affect the distal conus medullaris and filum terminale exclusively, and cystic degeneration is reported in approximately 50% of the cases. Tumors of the conus medullaris are also observed in the pediatric population.

In the cranium, ependymomas are relatively rare intracranial gliomas and comprise only 5-6% of these tumors. They are typically more common in children.

Spinal schwannomas and myxopapillary ependymomas may have similar imaging characteristics, and a detailed examination of magnetic resonance T2W imaging and postcontrast T1W imaging may help facilitate their differentiation.[2]

Astrocytomas

Astrocytomas, another primary glial neoplasm, occur less frequently in the region of the conus medullaris and the filum terminale (just less than one third of cases) compared with ependymomas. Astrocytomas also have a slight male predominance and tend to occur in the third to fifth decade of life. In contrast to ependymomas, astrocytomas are the most common intra-axial brain tumor.

Other tumors

Other tumors of the spinal cord comprise less than one third of intramedullary spinal cord tumors. These include dermoid and epidermoid tumors, vascular tumors, hemangioblastomas, and, rarely, lymphomas[3] or oligodendrogliomas. Other rare tumors have been reported periodically.

Intradural-extramedullary tumors are predominantly (more than two thirds) schwannomas, neurofibromas, or meningiomas. The reported incidences of these are approximately equal. Lipomas have also been described. The exophytic components of intramedullary ependymoma and astrocytoma can occur and extend into the intradural-extramedullary compartment.

Cauda equina paragangliomas are rare, benign, slow-growing tumors, and the diagnosis is often made at surgery. They are wll encapsulated and cured by surgery, with radiotherapy reserved for only tumors that are incompletely resected. Tumor relapse may occur up to 30 years after surgery.[4]

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Etiology

Tumors of the nervous system and spinal cord are classified according to their cells of origin. The following is a modified classification by the World Health Organization.

Astrocytic tumors include the following:

  • Pilocytic astrocytoma - Grade I
  • Diffuse (fibrillary) astrocytoma (low grade) - Grade II
  • Anaplastic astrocytoma - Grade III
  • Glioblastoma- Grade IV

Oligodendroglial tumors include the following:

  • Oligodendroglioma
  • Anaplastic oligodendroglioma

Mixed gliomas include the following:

  • Oligoastrocytoma
  • Anaplastic oligoastrocytoma

Ependymal tumors include the following:

  • Ependymoma - Cellular, papillary, clear cell. tanycytic
  • Anaplastic ependymoma
  • Myxopapillary ependymoma

Neuronal and mixed neuronal-glial tumors include the following:

  • Gangliocytoma
  • Desmoplastic infantile astrocytoma/ganglioglioma
  • Dysembryoplastic neuroepithelial tumor
  • Ganglioglioma
  • Paraganglioma of the filum terminale

Tumors of meninges include the following:

  • Meningioma
  • Meningeal hemangiopericytoma

Tumors of nerve sheath cells include the following:

  • Schwannoma (ie, neurilemmoma)
  • Neurofibroma

Other tumors include the following:

  • Tumors of primitive undifferentiated cells (medulloblastoma)
  • Lymphoma [3] – Primary and secondary
  • Metastatic tumors

The histologic findings of the major tumor types are presented in Ependymoma; Low-Grade Astrocytoma; Meningioma; Dermoid, Limbal; Neurofibromatosis; and Lipomas.

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Pathophysiology

The distal or terminal region of the spinal cord, the conus medullaris and cauda equina, is a complex region of spinal anatomy and transition from the central to peripheral nervous system. The motor nerve roots of the cauda equina exit and sensory nerves enter through the conus and are considered peripheral nerves.

An isolated lesion at the conus therefore may causes symptoms of a lower motor neuron lesion with or without spinal cord symptoms. Therefore, the patient may present with various symptoms, from flaccid paralysis or paresis of the lower extremities to spasticity.

Early on, the symptoms may be unilateral and localized to a specific muscle group. The sensory deficit, at least initially, maybe localized to a unilateral dermatomal distribution. As lesions progress in size, symptoms may progress and become bilateral. The numbness and paresthesia progress to a saddle distribution and extend into the lower extremity.

Lesions of the conus medullaris may manifest as sensory dysfunction of the perineum in a saddle distribution and as bowel and bladder dysfunction. Patients may present with back pain that is primarily midline and less radicular in nature. Lesions that are truly isolated to the conus medullaris may demonstrate sparing of the lower extremities and affect only the bladder and perineum.

If the lesion is large enough to include some lumbar cord segments, symptoms extend into the lower extremities. If the lumbar cord is affected, the lesions have the characteristics of upper motor neuron lesions with hyperreflexic motor weakness.

Genitourinary (GU) dysfunction is present in persons with either conus medullaris lesions or cauda equina lesions. No distinct signs or symptoms differentiate one type of lesion from the other. Because the conus medullaris includes most of the sacral cord that controls GU function, a lesion frequently results in GU deficits. By comparison, the cauda equina has roots of both lumbar and sacral origin, and GU sparing may occur.

Both conus medullaris and cauda equina lesions are associated with urinary retention and incontinence and fecal incontinence or constipation. Both types of lesions maybe associated with sexual dysfunction, including erectile dysfunction and impotence.

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Clinical Presentation

The manifestations of spinal cord tumors may include myriad neurologic symptoms. Findings from a careful history and physical examination can help guide the clinician to the diagnosis of a spinal cord tumor. The evolution of symptoms may be slow and progressive, or it may be abrupt with rapid progression.

Neurologic symptoms affecting the distal nerve roots are known as the cauda equina syndrome or conus medullaris syndrome (see Cauda Equina and Conus Medullaris Syndromes). The following are the main elements of the neurologic presentation.

Pain

Pain is the most common symptom. Pain increases with movement or the Valsalva maneuver (if radicular). Pain that increases during recumbency, particularly at night, may suggest a spinal cord tumor.

The pain may be described as follows:

  • Radicular, usually of dermatomal distribution
  • Localized, near the midline of the spine
  • Medullary and nonradicular in distribution, possibly bilateral, and possibly described as burning or dysesthetic pain

Motor disturbance

Motor disturbance is the next most common symptom. Patients may present with the following:

  • Weakness
  • Ataxia
  • Clumsiness
  • Atrophy
  • Twitching and fasciculation
  • Gait disturbance

Other disturbances

Patients may present with the following nonpainful sensory disturbances:

  • Paresthesia
  • Dysesthesia
  • Dissociative syndrome (ie, decreased pain and temperature sensation while touch is preserved)
  • Radicular or medullary distribution

Bowel and bladder dysfunction may be present. Patients may present with the following:

  • Sphincter problems
  • Possible incontinence, retention, and incomplete bowel or bladder evacuation
  • Possible erectile dysfunction and impotence

Physical deformity (visible mass over the area) may indicate a coronal deformity (scoliosis)

In one study of patients with cauda equina syndrome, findings included decreased anal tone (7.6%), fecal incontinence (3.8%), urinary retention (7.6%), bladder incontinence (8.9%), constipation (2.5%), and saddle anesthesia (8.9%).[5]  

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Differential Diagnosis

The differential diagnosis for lumbosacral cord dysfunction includes nonneoplastic causes of myelopathy.

An expanded differential diagnosis is presented in the Medscape Reference article Cauda Equina and Conus Medullaris Syndromes.

The following are some of the major groupings: congenital, acquired, vascular, infectious, and autoimmune and degenerative.

Congenital

Syringomyelia is a cystic cavitation of the spinal cord that may communicate with the central canal or the subarachnoid space. It can be congenital or posttraumatic.

Acquired

A herniated lumbar disk can cause nerve root impingement, usually in the setting of congenital stenosis. Quite often, it manifests as sciatica or radiculopathy. A herniated disk may be associated with the following:

  • Pain radiating to the lower extremity
  • Motor weakness in a specific distribution
  • Sensory loss or paresthesia in a specific dermatomal pattern
  • Diminished reflexes

Spinal stenosis can be the result of a congenitally shallow canal, with the following:

  • Arthropathy of the facet
  • Hypertrophied ligamentum flavum
  • A bulging annulus or herniated disc

With neurogenic claudication (compared with vascular claudication), the pain is dermatomal and worsens with ambulation.

In the setting of major trauma, fractures are likely nonpathologic. The bony fragments can compress the neural elements.

Vascular

Epidural spinal hematoma may be posttraumatic; in anticoagulated patients, minor trauma presumably may be the cause. Alternatively, it may result from a dural vascular malformation. Arteriovenous malformations may cause a hemorrhage that affects the conus medullaris but is less likely to affect individual roots.

Infarction may result from disruption of the radicular vessels as a result of atherosclerotic disease of the aorta or another disease. The cord is especially at risk if infarction affects the L2 vessel (ie, artery of Adamkiewicz, usually on the left).

Infectious

The presentation in patients with epidural abscess may include fever, back pain, and localized tenderness. Risk factors include intravenous drug abuse, diabetes, and renal failure. Staphylococcus aureus is the major causative organism. Typically, patients have an elevated erythrocyte sedimentation rate and WBC count.

Vertebral osteomyelitis is an infection of the vertebral bodies. The lumbar area is affected most commonly. Tuberculous osteomyelitis or spondylitis is referred to as Pott disease.

Diskitis is an infection of the nucleus pulposus. Causative organisms include Escherichia coli and Staphylococcus, Streptococcus, and Pseudomonas species. Diskitis may be spontaneous or may occur following a procedure, such as discectomy.

Autoimmune and degenerative disorders

These disorders include the following:

  • Transverse myelitis
  • Multiple sclerosis
  • Viral infection or its sequela
  • Amyotrophic lateral sclerosis
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Workup Overview

The diagnostic workup overlaps, in part, with the workup presented in the Medscape Reference articles Cauda Equina and Conus Medullaris Syndromes and Neoplasms, Spinal Cord.

In general, findings from the history and physical examination are most helpful in categorizing the symptoms, developing a differential diagnosis, and guiding the diagnostic workup.

Tumors of the conus and cauda equina quite often have an insidious and potential progressive nature. Because the symptoms affect sexual capacity and bowel and bladder function, they are sometimes discounted by patients or dismissed as psychological. In women, the symptoms may be attributed to a cystocele or other urologic disease, while in older men, they can be attributed to prostate disease. Quite often, the correct diagnosis is not made until profound neurologic deficits have occurred.

A heightened index of suspicion should be maintained when dealing with patients with undiagnosed chronic conditions including lower extremity weakness, sensory problems and physical findings. Particular evaluation should be for patients with evolving or rapidly progressing neurologic deficits.

Most patients with back pain do not have spinal tumors. Thus, the diagnosis is frequently not considered until an imaging study is performed.

The emergency department (ED) workup for patients who present with persistent back pain or subacute or chronic neurological deficits should include an interview and a careful examination and timely referral if findings are present.

The consensus is that laboratory studies are not helpful in obtaining a diagnosis; however, laboratory study findings may help screen for and possibly exclude other disease processes. For example, an abnormal erythrocyte sedimentation rate (ESR), C-reactive protein level, and possibly an elevated WBC count may lead to the consideration of an epidural abscess.

With regard to studies of the urinary tract, back pain with positive urinalysis results may suggest a genitourinary (GU) etiology. Renal ultrasonography or a GU CT scan can be diagnostic.

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Magnetic Resonance Imaging

MRI with gadolinium is the imaging study of choice because it provides a detailed assessment of the neural tissue, other soft tissue, and bone. Tumors of the conus and cauda equina, such as meningioma, neurofibroma, and ependymoma, typically enhance with contrast. MRI provides information on the spinal canal and the anatomic location of the lesion, whether intradural in location and either intra- or extramedullary.[5, 2]

The relationship of the lesion to the normal structures (spinal cord and roots) can often be demonstrated. The intervertebral disks can also be visualized and can be assessed for concomitant disk disease.

In an MRI study of patients with spinal schwannomas or myxopapillary ependymomas, of the schwannoma group, all 24 tumors that were homogeneously hyperintense on the T2-weighted (T2W) images showed rim enhancement on the postcontrast T1-weighted (T1W) images. Moreover, all 14 of the schwannomas with homogeneous enhancement on the postcontrast T1W images were isointense on the T2W images. In the  myxopapillary ependymoma group, however, all 8 of the tumors that were homogeneously hyperintense on T2W images showed homogeneous enhancement on their postcontrast T1W images.[2]

 

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Plain Radiographs

Plain radiographs are of limited value but may be helpful for detecting bony lesions and other osseous abnormalities that are either extra-axial or have been present for a long time and caused osseous changes.

Tumors of the cauda equina are frequently present for years prior to diagnosis. They can cause bone erosion, which may be visible on radiographs.

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Computed Tomography

CT scan with myelography was used extensively until MRI became readily available.

Myelography is an invasive procedure and requires injection of contrast material directly into the subarachnoid space. As a result of the dural puncture, the patient may experience headaches due to a persistent spinal fluid leakage.

This modality does not allow visualization of the intramedullary spinal cord and therefore should be used only in patients who cannot tolerate an MRI (ie, a patient with a cardiac pacemaker).

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Other Studies

Bone scans maybe helpful to identify inflammatory, infectious, or neoplastic lesions. However, they do not provide high-resolution anatomical detail, do not help visualize neural tissue, and are not typically used in the workup for spinal cord tumors.

Duplex ultrasound findings, in the setting of back pain or claudication, can help exclude an aortic aneurysm or other vascular etiology as causes of back or leg pain. However, ultrasonography is not usually employed as an initial diagnostic tool.

Electromyelography (EMG) and nerve conduction studies (NCS) may be useful in the differential diagnosis of lower extremity pain, weakness, or sensory loss. Tumors of the low spine may cause a radiculopathy detectable on EMG. Findings do not provide any anatomical detail regarding the lesions, but they may help localize the involvement of a particular motor root.

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Treatment Approach

Surgical excision is the primary modality of treatment for spinal tumors. Urgent or emergent surgery should be performed in patients with rapidly progressing neurologic deficits.

Radiation therapy and intrathecal chemotherapy are reasonable adjuvants for the treatment of these tumors in patients with contraindications for surgical treatment.

Medical treatment of the patient is focused on optimizing the treatment of any chronic medical condition that may limit functional status. Presently, very limited types of medications, including chemotherapies, are used to treat these diseases.

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Tumor Resection

Surgical resection entails opening the dura mater and exposing the spinal cord. Once localized, typically with ultrasound, the spinal cord in incised in the midline. The lesion in entered and then a biopsy is obtained. If the lesion is an invasive neoplasm (astrocytoma), the procedure is halted if resection planes cannot be established. With benign lesions, resection along tissue planes may provide a gross total resection, which is the optimal goal.

Adjuvant radiation therapy or intrathecal chemotherapy is used in selected cases or unresectable neoplasms.

Contraindications for surgery relate to the overall health, condition of the patient as well as overall life expectancy of the patient. Patients with significant comorbidity are poor candidates for any surgery, including spinal surgery. A relative contraindication for surgery is tumors that are in a difficult anatomical location, especially on the ventral aspect of the cord. However, experienced surgeons using microsurgical techniques can obtain the appropriate exposure. Fortunately, the roots of the cauda equina may be retracted gently to provide for exposure of most tumors in this area.

Preoperative details

Informed consent should be obtained from patients or their guardians. A realistic portrayal of the results should be presented, and the expectations of the patient should be addressed. Neurologic deficits may not improve, and a risk of worsening exists, including pain, paralysis, paresthesia, bowel or bladder problems, and sexual dysfunction.

When preparing for surgery, pay special attention to the cardiopulmonary status and the correction of any coagulation, electrolyte, or metabolic disorders. A careful neurological examination is also required. The objective is to have a baseline assessment against which to detect any postoperative neurologic deterioration.

Some surgeons routinely pretreat patients with one or several doses of steroids (eg, dexamethasone). Steroids may help with perioperative edema or may improve the tolerance of neurologic tissue, and patients may have improved outcomes.

Patients on anticoagulation therapy or aspirin prophylaxis should stop their medications prior to surgery. Obtain laboratory confirmation to demonstrate that the coagulation profile and bleeding time or in vitro platelet function analysis are acceptable.

Intraoperative details

Prophylactic antibiotic is administered intraoperatively within 1 hour of skin incision (preferably before skin incision). A posterior laminectomy is performed over the appropriate lumbar or thoracic region. An intraoperative ultrasound study is typically performed if a question remains about the extent or precise localization of the tumor.

The dura mater is opened and the spinal cord divided in the midline. For delicate debulking of the tumor, an operating microscope and microsurgical instruments are used. An ultrasonic aspirators or surgical laser may be helpful with intramedullary lesions so as not to disrupt tissue planes.

The area around the tumor may have increased vascularity with enlarged veins. Special care should be taken when performing a myelotomy (opening of the spinal cord). Stay sutures in the pia may be used to help with the exposure. Although a cavity is left after the procedure, the defect in the neural tissue does not need to be closed. The dura is closed in the usual watertight manner.

Attention to hemostasis is essential. Some intradural-intramedullary tumors separate out readily, while others need to be removed in a piecemeal manner. Tumors of the cauda equina are usually easier to remove completely, compared with those of the conus, because they are extramedullary. Special care should be taken with removal of dermoid and epidermoid tumors. Spilling their irritating content into the subarachnoid space may potentially cause adhesions, arachnoiditis, and inflammation.

Postoperative details

Attention should be given to any potential cardiovascular or pulmonary problems. Postoperatively, patients should be given prophylaxis for deep vein thrombosis. Some surgeons use a brief course of postoperative steroids and antibiotics. Serial neurologic examinations should be performed. In addition, resumption of normal bowel and bladder function should be monitored carefully. A postoperative imaging study (MRI) should be obtained to confirm resection of the lesion or the extent of postoperative residual tumor.

Follow-up

Provide patients appropriate follow-up care and instructions. Provide discharge instructions from the hospital, with explicit instructions about wound infection and any neurologic deterioration. Follow-up visits for wound care should be conducted in a timely fashion.

Secure appointments for possible adjuvant chemotherapy or radiation therapy.[6, 7]

The patient should be observed periodically for a period of several years to monitor for recurrence.

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Complications of Surgery and Postsurgical Pain

Complications of spinal surgery are similar to those for any other major surgery, including the risks of anesthesia, acute myocardial infarction, deep venous thrombosis, pulmonary embolism, pneumonia, and other pulmonary complications.

Careful preoperative screening and preparation of patients, attention to details, and aggressive postsurgical rehabilitation can help minimize the risk of these complications.

Pain

Postsurgical pain resulting from manipulation of neural tissue has been categorized as either somatic or central.

Somatic or acute pain results from manipulation of nerves and nerve roots. One example is traumatic retraction of a nerve root during surgery during manipulation and dissection. Steroids (eg, dexamethasone) may be helpful for easing the pain, presumably by minimizing inflammation. Prolonged use of narcotics should be avoided, but they can be used for short-term relief.

Central pain results from resection of intramedullary tumors and is a chronic, persistent pain that is difficult to control. The pain is described as gnawing, sometimes burning, which can be triggered by light touch and may extend well beyond the area of stimulation. The mechanisms are not well understood, and the pain does not respond well to drugs or stimulators.

Worsening of neurologic deficits

The exposure and manipulation of the cord and the dural sac, the spinal cord, or the nerve roots can cause a worsening of neurological deficits. Great care must be taken with dissection and manipulation of the spinal cord, especially with tumors that are large and occupy most of the spinal canal.

Infection

Patients are at risk for wound infection or meningitis. Risk factors for infectious complications include diabetes, obesity, revision surgery, and prior radiation therapy or chemotherapy.

Postoperative hematoma

A hematoma in the surgical area is recognized by immediate progressive deterioration of spinal cord or nerve root function. Radiologic confirmation can be obtained by performing a CT scan or MRI of the surgical area. If radiographic studies are not available, the surgeon should consider reexploring the surgical site. Aggressive management of a possible hematoma may protect against permanent neural deficits.

Postoperative spinal fluid leak

This complication occurs as a result of an incompletely closed dura, perhaps discovered after noticing poor healing of the skin and soft tissue over the incision site. In general, a patient who has had prior radiation therapy is more likely to develop this problem.

Postoperative instability after extensive laminectomy

Small laminectomies of the lumbar region do not usually result in the development of instability; however, more extensive laminectomies (>3 levels) and those that are wide and possibly involve the articular facets may result in instability. Younger patients are at a higher risk for developing instability as well as patients with severe neurologic deficits.

Flexion/extension plain radiographs prior to surgery may be compared to postoperative films. If progressive subluxation or a swan-neck deformity is identified, a stabilization procedure is indicated. The earlier the intervention is performed, the better the results.

Residual neurologic complications

These may include paresis or paralysis, spasticity, contractures, sensory deficits, bowel and bladder dysfunction, and erectile dysfunction. Preoperative deficits may improve after surgical intervention.

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Prognosis

In general, the earlier the detection of the tumor and the more minor the neurological deficit, the better the prognosis for treatment and recovery. Advanced age and severe neurologic deficit are associated with a poor prognosis. Correlation of the American Spinal Cord Injury Association (ASIA) impairment scale score and prognosis is presented in the Medscape Reference article Cauda Equina and Conus Medullaris Syndromes.

Series of patients have reported a low incidence of recurrence. In general, recurrence depends on the grade of the tumor, the stage at which it was recognized, the completeness of resection, and the use of adjuvant radiation therapy or chemotherapy.

Patients with cauda equina tumors fare extremely well due to the high incidence of complete resection with a high survival rate and recovery of function. Patients with conus medullaris tumors also have a good prognosis. Patients with a gross total resection have a better outcome. Patients with ependymomas of the conus medullaris have 5-year survival rates of 70-100%. The long-term recurrence rates are reported to be 0-30%.

For astrocytoma, the survival rate at 1-5 years is 20-70%. The tumor is infiltrative; therefore, identifying a plane of cleavage and dissection is more difficult. Usually, astrocytomas have a high incidence of recurrence, and mortality is correlated directly with recurrence. Incidences of intra-axial dissemination are also reported with aggressive or high-grade astrocytomas (grade 3 and 4).

Some small series report a complete cure of the lowest grade astrocytomas (grade 1), referred to as pilocytic astrocytomas. Some series demonstrate that patients receiving adjuvant radiation therapy or chemotherapy tend to fare better. Other series demonstrate excellent results without adjuvant therapy.

In children with ependymoma, favorable results have also been achieved without radiation therapy. The risk-to-benefit considerations may justify avoiding postoperative radiation therapy in pediatric patients. In one study, up to 18% of patients experienced postoperative neurological deterioration; however, in the majority of these cases, such deterioration was transient.[8] The new, postoperative neurological deficits were permanent in only in 6% of the patients with neurological deterioration.[8]

The reversal of neurological deficits depends on the extent of the dysfunction at the time of presentation. Patients with severe neurologic impairment are less likely to improve. In some instances of severe deficits, complete or near-complete recovery occurs. Predicting which patients will have significant neurologic improvement is difficult. Patients at advanced ages do not fare as well as younger patients with similar lesions.

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Contributor Information and Disclosures
Author

James S Harrop, MD Associate Professor, Departments of Neurological and Orthopedic Surgery, Jefferson Medical College of Thomas Jefferson University

James S Harrop, MD is a member of the following medical societies: American Association of Neurological Surgeons, American College of Surgeons, American Spinal Injury Association, North American Spine Society, Congress of Neurological Surgeons, Cervical Spine Research Society

Disclosure: Received consulting fee from Depuy spine for consulting; Received none from Geron for none; Received none from Neural Stem for none; Received ownership interest from Axiomed for none; Received honoraria from Stryker Spine for none.

Coauthor(s)

Amiram Shneiderman, MD Assistant Program Director, Co-Director of Quality Assurance, Department of Emergency Medicine, Martin Luther King-Charles Drew Medical Center

Amiram Shneiderman, MD is a member of the following medical societies: American College of Emergency Physicians, American Medical Association, Society for Neuroscience

Disclosure: Nothing to disclose.

George M Ghobrial, MD Resident Physician, Department of Neurological Surgery, Thomas Jefferson University Hospital

Disclosure: Nothing to disclose.

Tristan B Fried Student Medical Researcher, Thomas Jefferson Hospital; Student Researcher (STAR), Department of Dermatology, Hahnemann University

Disclosure: Nothing to disclose.

Specialty Editor Board

Francisco Talavera, PharmD, PhD Adjunct Assistant Professor, University of Nebraska Medical Center College of Pharmacy; Editor-in-Chief, Medscape Drug Reference

Disclosure: Received salary from Medscape for employment. for: Medscape.

Ryszard M Pluta, MD, PhD Associate Professor, Neurosurgical Department Medical Research Center, Polish Academy of Sciences, Poland; Clinical Staff Scientist, Surgical Neurology Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health (NIH); Fishbein Fellow, JAMA

Ryszard M Pluta, MD, PhD is a member of the following medical societies: Polish Society of Neurosurgeons, Congress of Neurological Surgeons

Disclosure: Nothing to disclose.

Chief Editor

Brian H Kopell, MD Associate Professor, Department of Neurosurgery, Icahn School of Medicine at Mount Sinai

Brian H Kopell, MD is a member of the following medical societies: Alpha Omega Alpha, American Association of Neurological Surgeons, International Parkinson and Movement Disorder Society, Congress of Neurological Surgeons, American Society for Stereotactic and Functional Neurosurgery, North American Neuromodulation Society

Disclosure: Received consulting fee from Medtronic for consulting; Received consulting fee from St Jude Neuromodulation for consulting; Received consulting fee from MRI Interventions for consulting.

Additional Contributors

Paul L Penar, MD, FACS Professor, Department of Surgery, Division of Neurosurgery, Director, Functional Neurosurgery and Radiosurgery Programs, University of Vermont College of Medicine

Paul L Penar, MD, FACS is a member of the following medical societies: Alpha Omega Alpha, American Association of Neurological Surgeons, World Society for Stereotactic and Functional Neurosurgery, Congress of Neurological Surgeons

Disclosure: Nothing to disclose.

References
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