Tumors in the Conus ,Cauda Equina
Author: Sagar Jung Rana, MD,Frcs, Senior Neuro Surgeon ,Departments of Neurosurgery,St.George Mahabert Hospital and Research Center ,Las Vegas,NV
Contributor Information and Disclosures
Updated: May 27, 2009
Introduction
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.
Tumors of the cauda equina and the conus medullaris manifest with progressive symptoms, including pain, motor weakness, sensory deficit, and bowel and bladder symptoms. These symptoms are collectively known as the cauda equina syndrome (see the eMedicine article Cauda Equina Syndrome). Tumors, disk herniations, fractures, and infection (ie epidural abscesses) are all possible causes of this 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.
For excellent patient education resources, visit eMedicine's Back, Ribs, Neck, and Head Center; Cancer and Tumors Center; and Brain and Nervous System Center. Also, see eMedicine's patien
education articles Back Pain, Lumbar Laminectomy, and Cauda Equina Syndrome.
Tumor of the conus medullaris.
Tumor of the conus medullaris
History of the Procedure
In 1887, Sir Victor Horsley performed the first successful
removal of spinal cord tumor in a British Army major, William Gowers. He had an extramedullary-intradural fibromyxoma compressing the spinal cord that was removed after general anesthesia and a laminectomy. The patient was able to subsequently regain his 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. Then 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.
Problem
Patients present due to a deterioration of neurologic function or pain. These tumors of the spinal cord can cause significant dysfunction due to compression of the spinal cord and nerve roots. Patient may present with weakness, sensory changes, bowel/bladder dysfunction, and pain due to the interference of these nerve pulses.
The general classification 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
o Arise inside the dural sac, from the leptomeninges or the nerve root
o Outside the substance of the spinal cord parenchyma
• Intramedullary tumors - Arise within the substance of the spinal cord
Frequency
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 are 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.
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, tend to affect the distal conus medullaris and filum terminale exclusively, and cystic degeneration in 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, typically more common in children.
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 of the spinal cord comprise less than one third of intramedullary spinal cord tumors. This includes dermoid and epidermoid tumors, vascular tumors, hemangioblastomas, and, rarely, lymphomas or oligodendrogliomas. Other rare tumors have been reported periodically.
Intradural-extramedullary tumors are predominantly (more than two thirds) schwannomas, neurofibromas, or meningiomas. Their reported incidence is approximately equal. Lipomas have also been described. The exophytic components of intramedullary ependymoma and astrocytoma can occur and extend into the intradural-extramedullary compartment.
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:
Tumors of the neuroepithelial tissue
• Astrocytic tumors
o Pilocytic astrocytoma - Grade I
o Diffuse (fibrillary) astrocytoma (low grade) - Grade II
o Anaplastic astrocytoma - Grade III
o Glioblastoma- Grade IV
• Oligodendroglial tumors
o Oligodendroglioma
o Anaplastic oligodendroglioma
• Mixed gliomas
o Oligoastrocytoma
o Anaplastic oligoastrocytoma
• Ependymal tumors
o Ependymoma
Cellular
Papillary
Clear cell
Tanycytic
o Anaplastic ependymoma
o Myxopapillary ependymoma
• Neuronal and mixed neuronal-glial tumors
o Gangliocytoma
o Desmoplastic infantile astrocytoma / ganglioglioma
o Dysembryoplastic neuroepithelial tumour
o Ganglioglioma
o Paraganglioma of the filum terminale
• Tumors of primitive undifferentiated cells (Medulloblastoma)
• Tumors of meninges
o Meningioma
o Meningeal hemangiopericytoma
• Tumors of nerve sheath cells
o Schwannoma (ie, neurilemmoma)
o Neurofibroma
• Lymphoma
o Primary
o Secondary
• Metastatic tumors
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 types of 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.
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 symptoms (see Cauda Equina Syndrome) or conus medullaris syndrome (see the eMedicine article Cauda Equina and Conus Medullaris Syndromes. The following are the main elements of the neurologic presentation:
• Pain (the most common symptom)
o Pain increases with movement or the Valsalva maneuver (if radicular).
o Pain that increases during recumbency, particularly at night, may suggest a spinal cord tumor.
o 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 (next most common symptom)
o Weakness
o Ataxia
o Clumsiness
o Atrophy
o Twitching and fasciculation
o Gait disturbance
• Nonpainful sensory disturbances
o Paresthesia
o Dysesthesia
o Dissociative syndrome (ie, decreased pain and temperature sensation while touch is preserved)
o Radicular or medullary distribution
• Bowel and bladder dysfunction
o Sphincter problems
o Possible incontinence, retention, and incomplete bowel or bladder evacuation
o Possible erectile dysfunction and impotence
• Physical deformity (visible mass over the area), which may indicate a coronal deformity (scoliosis)
Differential diagnosis
The differential diagnosis for lumbosacral cord dysfunction includes nonneoplastic causes of myelopathy. An expanded differential diagnosis is presented in the eMedicine article Cauda Equina Syndrome. The following are some of the major groupings:
• Congenital
o Tethered cord syndrome: This is an abnormally low conus medullaris that is associated with a short thickened filum terminale and is most common in children with myelomeningocele. It can also be present in adults. Adults are initially asymptomatic and may develop symptoms after trauma.
o Syringomyelia: This 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
o Herniated lumbar disk: This causes nerve root impingement, usually in the setting of congenital stenosis. Quite often, it manifests as sciatica or radiculopathy. A herniated disk maybe 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
o Spinal stenosis: This 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
o Neurogenic claudication (compared with vascular claudication): The pain is dermatomal and worsens with ambulation.
o Fractures: In the setting of major trauma, these fractures are likely nonpathologic. The bony fragments can compress the neural elements.
• Vascular
o Hemorrhage or hematoma: Epidural spinal hematoma may be posttraumatic, the result of anticoagulation with presumed minor trauma, or a dural vascular malformation.
o Arteriovenous malformations: These may cause a hemorrhage that affects the conus medullaris but is less likely to affect individual roots.
o Infarction: This 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
o Epidural abscess: The presentation 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 sedimentation rate and WBC count.
o Vertebral osteomyelitis: This is an infection of the vertebral bodies. The lumbar area is affected most commonly. Tuberculous osteomyelitis or spondylitis is referred to as Pott disease.
o Diskitis: This 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.
• Syrinx
o Posttraumatic
o Congenital
• Autoimmune and degenerative disorders
o Transverse myelitis
o Multiple sclerosis
o Viral infection or its sequela
o Amyotrophic lateral sclerosis
o Guillain-Barré syndrome
Indications
Surgical considerations
Surgical excision is the primary modality of treatment for spinal tumors. 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. The correlation of the American Spinal Injury Association (ASIA) score and prognosis are presented in the eMedicine article Cauda Equina Syndrome.
When preparing for surgery, pay special attention to the cardiopulmonary status and the correction of any coagulation, electrolyte, or metabolic disorders.
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.
Indications for surgery
The management of spinal cord tumors is primarily surgical. 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.
Relevant Anatomy
Nerve fibers descend and ascend from 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 may terminate along the canal by typically is 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.
Contraindications
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.
Author: Sagar Jung Rana, MD,Frcs, Senior Neuro Surgeon ,Departments of Neurosurgery,St.George Mahabert Hospital and Research Center ,Las Vegas,NV
Contributor Information and Disclosures
Updated: May 27, 2009
Introduction
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.
Tumors of the cauda equina and the conus medullaris manifest with progressive symptoms, including pain, motor weakness, sensory deficit, and bowel and bladder symptoms. These symptoms are collectively known as the cauda equina syndrome (see the eMedicine article Cauda Equina Syndrome). Tumors, disk herniations, fractures, and infection (ie epidural abscesses) are all possible causes of this 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.
For excellent patient education resources, visit eMedicine's Back, Ribs, Neck, and Head Center; Cancer and Tumors Center; and Brain and Nervous System Center. Also, see eMedicine's patien
education articles Back Pain, Lumbar Laminectomy, and Cauda Equina Syndrome.
Tumor of the conus medullaris.
Tumor of the conus medullaris
History of the Procedure
In 1887, Sir Victor Horsley performed the first successful
removal of spinal cord tumor in a British Army major, William Gowers. He had an extramedullary-intradural fibromyxoma compressing the spinal cord that was removed after general anesthesia and a laminectomy. The patient was able to subsequently regain his 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. Then 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.
Problem
Patients present due to a deterioration of neurologic function or pain. These tumors of the spinal cord can cause significant dysfunction due to compression of the spinal cord and nerve roots. Patient may present with weakness, sensory changes, bowel/bladder dysfunction, and pain due to the interference of these nerve pulses.
The general classification 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
o Arise inside the dural sac, from the leptomeninges or the nerve root
o Outside the substance of the spinal cord parenchyma
• Intramedullary tumors - Arise within the substance of the spinal cord
Frequency
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 are 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.
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, tend to affect the distal conus medullaris and filum terminale exclusively, and cystic degeneration in 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, typically more common in children.
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 of the spinal cord comprise less than one third of intramedullary spinal cord tumors. This includes dermoid and epidermoid tumors, vascular tumors, hemangioblastomas, and, rarely, lymphomas or oligodendrogliomas. Other rare tumors have been reported periodically.
Intradural-extramedullary tumors are predominantly (more than two thirds) schwannomas, neurofibromas, or meningiomas. Their reported incidence is approximately equal. Lipomas have also been described. The exophytic components of intramedullary ependymoma and astrocytoma can occur and extend into the intradural-extramedullary compartment.
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:
Tumors of the neuroepithelial tissue
• Astrocytic tumors
o Pilocytic astrocytoma - Grade I
o Diffuse (fibrillary) astrocytoma (low grade) - Grade II
o Anaplastic astrocytoma - Grade III
o Glioblastoma- Grade IV
• Oligodendroglial tumors
o Oligodendroglioma
o Anaplastic oligodendroglioma
• Mixed gliomas
o Oligoastrocytoma
o Anaplastic oligoastrocytoma
• Ependymal tumors
o Ependymoma
Cellular
Papillary
Clear cell
Tanycytic
o Anaplastic ependymoma
o Myxopapillary ependymoma
• Neuronal and mixed neuronal-glial tumors
o Gangliocytoma
o Desmoplastic infantile astrocytoma / ganglioglioma
o Dysembryoplastic neuroepithelial tumour
o Ganglioglioma
o Paraganglioma of the filum terminale
• Tumors of primitive undifferentiated cells (Medulloblastoma)
• Tumors of meninges
o Meningioma
o Meningeal hemangiopericytoma
• Tumors of nerve sheath cells
o Schwannoma (ie, neurilemmoma)
o Neurofibroma
• Lymphoma
o Primary
o Secondary
• Metastatic tumors
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 types of 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.
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 symptoms (see Cauda Equina Syndrome) or conus medullaris syndrome (see the eMedicine article Cauda Equina and Conus Medullaris Syndromes. The following are the main elements of the neurologic presentation:
• Pain (the most common symptom)
o Pain increases with movement or the Valsalva maneuver (if radicular).
o Pain that increases during recumbency, particularly at night, may suggest a spinal cord tumor.
o 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 (next most common symptom)
o Weakness
o Ataxia
o Clumsiness
o Atrophy
o Twitching and fasciculation
o Gait disturbance
• Nonpainful sensory disturbances
o Paresthesia
o Dysesthesia
o Dissociative syndrome (ie, decreased pain and temperature sensation while touch is preserved)
o Radicular or medullary distribution
• Bowel and bladder dysfunction
o Sphincter problems
o Possible incontinence, retention, and incomplete bowel or bladder evacuation
o Possible erectile dysfunction and impotence
• Physical deformity (visible mass over the area), which may indicate a coronal deformity (scoliosis)
Differential diagnosis
The differential diagnosis for lumbosacral cord dysfunction includes nonneoplastic causes of myelopathy. An expanded differential diagnosis is presented in the eMedicine article Cauda Equina Syndrome. The following are some of the major groupings:
• Congenital
o Tethered cord syndrome: This is an abnormally low conus medullaris that is associated with a short thickened filum terminale and is most common in children with myelomeningocele. It can also be present in adults. Adults are initially asymptomatic and may develop symptoms after trauma.
o Syringomyelia: This 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
o Herniated lumbar disk: This causes nerve root impingement, usually in the setting of congenital stenosis. Quite often, it manifests as sciatica or radiculopathy. A herniated disk maybe 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
o Spinal stenosis: This 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
o Neurogenic claudication (compared with vascular claudication): The pain is dermatomal and worsens with ambulation.
o Fractures: In the setting of major trauma, these fractures are likely nonpathologic. The bony fragments can compress the neural elements.
• Vascular
o Hemorrhage or hematoma: Epidural spinal hematoma may be posttraumatic, the result of anticoagulation with presumed minor trauma, or a dural vascular malformation.
o Arteriovenous malformations: These may cause a hemorrhage that affects the conus medullaris but is less likely to affect individual roots.
o Infarction: This 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
o Epidural abscess: The presentation 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 sedimentation rate and WBC count.
o Vertebral osteomyelitis: This is an infection of the vertebral bodies. The lumbar area is affected most commonly. Tuberculous osteomyelitis or spondylitis is referred to as Pott disease.
o Diskitis: This 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.
• Syrinx
o Posttraumatic
o Congenital
• Autoimmune and degenerative disorders
o Transverse myelitis
o Multiple sclerosis
o Viral infection or its sequela
o Amyotrophic lateral sclerosis
o Guillain-Barré syndrome
Indications
Surgical considerations
Surgical excision is the primary modality of treatment for spinal tumors. 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. The correlation of the American Spinal Injury Association (ASIA) score and prognosis are presented in the eMedicine article Cauda Equina Syndrome.
When preparing for surgery, pay special attention to the cardiopulmonary status and the correction of any coagulation, electrolyte, or metabolic disorders.
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.
Indications for surgery
The management of spinal cord tumors is primarily surgical. 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.
Relevant Anatomy
Nerve fibers descend and ascend from 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 may terminate along the canal by typically is 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.
Contraindications
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.
The 1887 operation by Horsley on a tumour of the spine was diagnosed by Sir William Gowers, the neurologist. The patient was an army officer. You write that Gowers was the army officer
ReplyDelete