Chapter 16 Spinal Cord Disorders

by Arthur Ericsson, M.D. 16.1 Goals for the Medical Student

1. Describe the major functions and modalities ascribed to the spinal cord.

2. Anatomy:

(a) Describe the relationship of the cord to the bony spine. At what level does the conus medullaris end?

(b) Identify the following tracts, the modalities carried in each, and the longitudinal path of each, noting the level at which they decussate and synapse: spinothalamic, dorsal columns, and Corticospinal tract.

3. Localize the lesions giving the following findings:

(a) Ipsilateral UMN and lpositioii sefise, with coiitralaterat ipaiii and teinp sensation, i.e. a BrownS6quard Syndrome.

(b) Dissociated sensory loss, weakness, and areflexia of the upper extremity.

(c) Sensory level with paraparesis and bladder incontinence.

4. Describe the usual clinical presentation of vitamin B,2 deficiency.

16.2 Anatomy and Physiology 16.2.1 Blood Supply To The Spinal Cord The blood supply of regions of the spinal cord, diagrammed in figure 16.1, is derived from branches from:

1. The vertebral, superior, intercostal and ascending cervical arteries, all arising from the subclavian arteries on both sides anastoliiosiiig richly and supplying the cervical and upper thoracic segments of the spirial cord.

2. The mid-thoracic area is supplied usually from a single intercostal artery at the level of T-6.

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Neurology Syllabus Elective Peading

Figure 16.1: The blood supply of regions of the spinal cord. Adapted from Carpenter, Core Text of Neuroaltatoniy.

3- The thoraco-luiiibar region is supplied from a large single arteria inagiia arising from the aorta just below the diaphragm (Artery of Adainkiewicz).

4. The cauda equina is supplied by a paired arteries arising from the iliac arteries.

The aiiterior and posterior of the cord are supplied by different arteries as shown in a cross-section of the spiiial cord in

figure 16.2. Blood is supplied from the aorta by way of the intercostal arteries, which form the anterior spinal artery. Perforating and septal branches supply the anterior 2/3 of the cord. A rich aiiastomosis is formed with the posterior spinal arteries and the circumflex vessels which supply the superficial surface of the spiiial cord. 16.2.2 Dynamic Blood Flow It has been shown that ascending and descending blood flow current exists in the anterior and posterior spinal cord arteries in man. Tile direction of these currents varies in normal cases. While water-shed areas do exist, reversals of blood flow current in the anterior spinal artery under pathological condition of occlusion of one or more vessels, do occur frequently and have been demonstrated angiographically. This may be the basis of spinal cord steal sytidroiiie and levels of iiifarction, other than that expected on the basis of the occlusion.

Spinal Cord Disorders Arthur Ericsson, M.D.

Figure 16.2: The cross-sectioiial blood supply of the spinal cord. Adapted from Carpenter, Core Text of Neuroanatomy. 16.3 Major Descending Motor Pathways 16.3.1 Corticospinal System Lateral Corticospinal Systern There are a number of pathways which comprise what is considered to be tile pyramidal system. Only a very small portion of what actually arises from motor strip (Area IV) and on stimulation, gives rise to movements of a discrete nature distally in the hand and foot opposite to the side of stimulation. These are supplemented I)y many fibers from other parts of Area IV and the s~called supplementary motor areas. No more than 20% of the fibers of the corticospinal or pyramidal system are uncrossed - the remaining 80% cross at the decussation. Ventral Corticospinal System Fibers which control neck, trunk, proximal limb girdle, upper and lower extremity linib girdle, and anti-gravity movements proceed primarily in the ventral pyramidal or ventral corticospinal tract, while those fibers functionally related to extremity movements are located in the lateral corticospinal tract. The lamination in the lateral corticospinal tract is such that the lower extremity fibers are more dorsal and lateral, and upper extremity is more medial and ventral in location. Most fibers terminate on internuncial neurons before synapsing with the anterior horn cells. 291

Neurology Syllabus Elective Reading 16.3.2 Rubrospinal System This is a major descending pathway arising from the red nucleus which crosses the midline and enters the spinal cord just ventral to the lateral corticospinal tract. The lowest descent of this pathway is in the loiver portion of the cervical cord- Undoubtedly extrapyramidal influence and regulation of head and eye movements is a function of this system. 16.3.3 Tectospinal System Rom the roof of the midbraiii arising from around the superior colliculus, the medial tectospinal pathway descends in juxtaposition to the medial longitudinal fasciculus, and in the anterior medial portion of the spinal cord to the lower cervical area. Functionally, it is associated with extrapyramidal discharge system of the head and eye movements. 16.3.4 Reticulospinal and Tegnientospinal Systems Throughout the reticular grey there are masses of cells which send fibers descending in the lateral part of the spinal cord in direct relationship to the interinediolateral column at thoracic levels. These are concerned primarily with sympathetic tone. 16.4 Ascending T)racts of the Spinal Cord

1. Spinocerebellar pathways. There are tivo major pathways that arise from Clarke's nucleus and run to the cerebellum. The first, tile dorsal spinocerebellar pathway lies lateral to the major descending motor pathways in the lateral funiculus of the cord. It is laminated with the upper cervical portion most anterior and lumbosacral portion is most dorsal. The anterior or ventral spinocerebellar pathway is laminated in precisely the same way but lies more anterior in the spinal cord at the periphery.

2. Lateral spinal ttialaiiiie tract. The lateral spinal thalaiiiie pathway arises from fibers with their cell bodies located in the dorsal

grey of the spinal cord. They cross and ascend in the anterolateral segiiaeiit of the spinal cord- This pathway is laniinated so that the toes are most dorsolateral and upper extremities are most veiitromedial. Temperature sensation is carried in the same pathway but on the inner surface and medial to the pain conduction. Major fibers are given off at medullary, pontine, iiieseiieephalic, and diencephalic levels prior to termination multisyliaptically in the contralateral thalamus. Temperature sensation is carried oil the medial surface of the ascending lateral spinal thalamic pathway at spinal cord levels as well as in brain stem levels-

3. Posterior columns. Nlonosyiial)tic fibers ascend with and without synapse in the dorsal grey and the posterior column to end in

the cuneate and gracile nuclei. A synapse with the fibers that ascend via the inedial leiiiiiiscus to the thalamus where they end in the %,eritralis inedialis and lateralis of the dorsal tllal~iiiius.

4. Sensory nuclei from the viscera. Fibers from the anterolateral column cross and ascend medial to the pyramidal system in the

lateral fuiiieulus of the spinal cord. They end in the medullary reticular grey and ascend niultisynaptically to the thalamus and hypothalamus.

In general, the pattern of sensory localization is comparatively simple. The peripheral localization is distinct for peripheral

nerve, as opposed to dorsal route; and, as each-successive synapse is added to the ascending pathway, the peripheral localization becomes less discrete but the variety of responses, i.e., different sensory iyiodalities, becomes more enhanced. Therefore, it is possible for comparatively specific localization to occur and, if correlated with the motor abnormality, a fairly specific localization is possible. 292

Spiiial Cord Disorders Arthur Ericsson, M.D.

Figure 16.3: The major ascending and descending pathways of the spinal cord. 293

Neurology Syllabus Elective Peading 16.5 Localizing Lesions to the Spinal Cord For the student the most important clinical task is to determine the location of the neurologic lesion. Is the lesion located in the brain, spinal cord, peripheral nerves, myoneural junction or muscle. Often the following signs would suggest to the student that the disease is primarily of spinal cord origin:

1. That there is an absence of any signs or symptoms which may be neuro-anatomically localizable above the neck: that is, that the patient shows normal cranial nerve function and cortical function.

2. That the DTR's or stretch reflexes are intact or even hyperactive indicates that the peripheral nerves are normal. The lesion may

reflect a disturbance at the level of the spinal cord; therefore, reflexes may be absent in acute spinal injury or hyperactive below that level.

3. That the sensory loss is specific for the specific level of a spinal cord lesion, (i.e., spinal level) and not radicular.

4. That the motor loss is also specific for a complete or incomplete spinal cord lesion (paraparesis or heiiiiparesi )-

5. That the bladder or bowel may not function. A loss of sphincter tone suggests involvement at the sacral cord level.

6. Specific spinal cord syndromes:

(a) Browii-S6quard syndrome may be manifested by ipsilateral loss of proprioception and vibration, spasticity below the

level of the lesion with lower motor neuron weakness at the level of the lesion and contralateral loss of pain and temperature.

(b) Conus medullaris syndrome is characterized by bladder and bowel paralysis with loss of potency and loss of sensation in

the saddle area.

(c) Cauda equina syndrome is characterized by paiii in the lumbosacral area with paraparesis and sensory loss.

(d) Anterior spinal artery syndrome is characterized by paraparesis and sensory loss for pain and temperature but not vibration and 1)ositioti.

16.5.1 Definitions

1. Spinal cord inyelopathy: Any type of spinal cord injury independent of cause: inflammatory, nutritional, metabolic, toxic, degenerative, and even turner with compression.

2. lvlyelitis: Iiiflaiiiiiiatioii of the spinal cord.

The causes of iiiyelol)atliy or myelitis include infaretion, infections, irradiation, collagen vascular disorder, deniyelinating

diseases, and subacute combined degeneration. 16.5.2 Clinical Presentation- Myelopathy The earliest symptoms include weakness of the lower extremities, niild sensory disturbance in the lower extremities, back or radicular pain and involvement of the bladder and bowel. In post-infectious njyelopathy there is an : terval between 1-2 weeks after the acute systemic infection and before the onset of myelopatliy.

in Spinal fluid may be normal or show an increased protein and cell count. There is no specific therapy. Multiple sclerosis, combined system disease (vitamin B12 deficiency) and SLE may cause myelopathy. 294

Spinal Cord Disorders Arthur Ericsson, M.D. 16.6 Specific Types of Myelopathy and Radiculopathy 16.6.1 Herniated disc A herniated disc may produce a myelopathy or, if below the level of the spinal cord, a radiculopathy and accounts for only about a 30-40% of backache, Herniation of a disc specifically refers to the extrusion of a piece of nucleus pulposus into the spinal canal. It commonly occurs between L5, Sl and L4 and L5, and becomes symptomatic when it displaces ligaments or compresses spinal nerve root or, in the cervical area, the spinal cord. In the lower segments the herniated disc compromises the lower segment. If L4-5 then it compresses L5 root by compressing it against the spinal canal. The myelogram is abnormal in over 95% of cases of herniated disc and the electroiiayogram becomes abnormal with fibrillations and complex units within 3-4 weeks after the compression of the nerve root. In general, there are two forms of therapy:

1. Medical Therapy: A 1-2 week trial of strict bed rest and/or traction which immobilizes the patient in bed and muscle relaxants is often somewhat helpful, as well as anti-inflammatory agents

2. Surgical Therapy: The positive indications for surgical therapy of a herniated disc are as follows:

(a) progressive neurologic deficit

(b) pain unrelieved by medical therapy

(c) loss of bowel or bladder control

(d) progressive atrophy in spite of relief of pain

If strict criteria is used in %-Iection of surgery, a greater than 85% relief of symptoms can be expected.

16.6.2 Spinal Cord T)rauma Pathophysiology: Basically, spinal cord injury maybe the result of direct penetrating injury or traumatic dislocation, or fracture of the vertebral column, or herniated disc. Trauma to the spinal cord causes edema, contusion, laceration, and may produce a functionally transected spinal cord. Cervical spondylosis represents the most common variety of chronic trauma to the spinal cord and accounts for about 50% of complaints froill older individuals. Painful, stiff neck, dermatoinal paiii and weakness in the upper extremities, or spastic paraparesis are the common syriiptoiiis and signs. Osteophytic encroachment on the spinal cord, the anterior spinal artery, or the iiitervertebral foramina accounts for the syinptoniatology. Nerve roots may thus be compressed, the spinal cord compressed anteriorly or within, and buckling of the ligaments posteriorly.

Clinical findings are characteristically symmetrical and while the symptoms usually begin after 40 ,years of age, the signs are usually:

1. Decreased vibratory sense distally

2. Increased DTP,'s in the lower extremities

3. Extensor plantar responses (Babinski) unilaterally or bilaterally

4. Light touch, pinprick and pain are often spared

5. Radicular symptoms: asymmetric weakness in the arms with fasciculations and decreased reflexes

6. Aching sensation in the iieck with radiation to the shoulder or hand

7. Dysesthesias with sensory loss in the root distribution

If acute trauma occurs, spinal shock may occur in which loss of function occurs below the level of the lesioii. Immobilization is a treatment of choice with surgical decompression if the inyelopatliy is acute and severe.

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Neurology Syllabus Elective Reading 16.6.3 Spinal Cord 'I'umors Spinal cord tumors may be defined by the location in which they occur. They are relatively uncommon and occur less than 1/8 as common as brain tumors.

1. Extradural tumors account for only 25% of spinal cord tumors and are usually metastatic to bone or primarily lymphogenous such as lymphomas, Hodgkin's and multiple myeloma as well as prostate.

2. Ititradural extramedullary tumors account for the bulk of spinal cord tumors and, in contrast, are usually benign, such as

ineniilgiomas and neurofibromas.

3. Intramedullary tumors usually are astrocytomas or ependymomas arising in the spinal cord and these account for only 1/5 of the tumors.

16.6.4 Syringomyelia An uncommon condition characterized by central cavitation of the spinal cord is syringomyelia. It is probably congenital and is often associated with Arnold-Chiari malformation. A cavitation occurs centrally or paracentrally in the spinal cord or brainstem. It extends anatomically from the paracentral region of the spinal cord, disrupting pain and temperature fibers. Symptoms are usually that of weakness and wasting of the small muscles of the hand with loss of paiii and temperature in the upper extremities. Reflexes in the lower extremities, however, are increased. There may be an associated Arnold-Chiari malformation, spina bifida, basilar impression, or hydrocephalus. 16.6.5 Clinical Appraisal of lumors A progressive disorder localizable to the spinal cord should raise the suspicion of spinal cord tunior. Radicular pain and loss of sensation in the sacral area are characteristic of extramedultary tumors. Intramedullary tumors and syringomyelia may be similar in syniptomatology usually lacking pain, and sensory abnormalities are maximal at the segmental levels involved. It should be remembered that the tumor is often higher than the level of the sensory loss and iiiyelograpliy is usually indicative of the location of the tunior - extradural, extraiiiedullary, intradural, or iiitramedullary.

The management of spinal cord tuniors is that of surgical therapy. Extradural tumors with metastatic carcinoma may be treated with radiotherapy., particularly the lymphomas and Hodgkin's disease. However, rapid progression of the neurologic syndromes are neurological emergencies and evidence of bowel or bladder dysfunction is indicative of irreversibility. If surgical decompression is delayed more than 48 hours after paraplegia is complete, it is usually not helpful. 16.7 References

1. Raichle and Posner- Treatment of extradural spinal cord compression. Neurology 20:391, 1970.

2. Baker, A.S., et. al. Spinal epidural abscess. NEJM 293: 463, 1975.

3. Browne, T.R., et. al. Hemangioblastomas of the spinal cord. Arch. Neurol. 33:435, 1976.

4. Hubbe, P. and Dam, A.M. Spastic paraplegia of unknown origin. A follow-up of 32 patients. Acta. Neurol. Scand. 49:536, 1973,

5. Silver, JR. and Buxton, P.H. Spinal stroke. Brain 97:539, 1974.

6. Tobin, W.D, and Layton, D.D. The diagnosis and natural liistor~v of spinal and arteriovenous malformations. Mayo Cl.

Proe. 51:637. 1976. 296

Spinal Cord Disorders Arthur Ericsson, M.D, 7. Gregorius, F.K., et. al. Cervical spondylotic radiculopathy and myelopathy. A long-term follow-up study. Arch. Neurol.

33:618, 1976. 8. Gilbert, R.W., Kim, J.H., Posner, J.B. Epidural spinal cord compression from metastatic tumor. Diagnosis and treatment.

Ann. Neurol. 3:40-51, 1978. 9. Cyriax, J. Dural pain. Lancet 1:919-921, 1978.

10. McQuarre, I.G. Recovery from paraplegia caused by spontaneous spinal epidural hematoma. Neurology 28:224-228, 1978. 11. Foster, J.B., et. al. The Association of Syringomyelia and Congenital Clinicomedullary animalis. Pathological evidence.

Brain 92:25-34, 1969. 12. Barnett, H.J.M., Foster, J.B., Hudgson, P. Syringomyelia. Philadelphia, W.B. Saunders Company, 1973. 13. Atcala, H. and Dodson, W.E. Syringobulbia as a cause of laryngeal strider in childhood. Neurology 25:875-878, 1975. 14. Barnerji, N.K., et. al. Chiari malformation presenting in adult life. Its relationship to syringomyelia. Brain 97: 157-168,

1974. 15. Altrocchi, P.H. Acute transverse inyelopathy. Arch. Neurol. 9:111-119, 1963- 16. Lipton, H.L. and Teasdall, R.D. Acute transverse inyelopathy in adults. Arch. Neurol. 28:252-257, 1973. 17. Schossberger, P. Vasculature of the spinal cord: A review. 1. Anatomy and physiology. II- Clinical considerations. Bull.

Los Angeles Neurol. Soc. 39:71-97, 1974. 18. Turnbull, I.M. Blood supply of the spinal cord: normal and pathological considerations. Clin. Neurosurg. 20:56-84, 1973. 19. Veron, J.P-, et. al. Acute necrotic iiiyelopatliy. Euro. Neurol. 11:83-96, 1974.

20. Weisman, A.D., Adanis, R.D. The neurological complications of dissecting aortic aneurysm. Brain 67:69-92, 1944. 297

Neurology Syllabus Elective Reading 16.8 Case Studies and Questions Case 1 A 69 year old newspaper publisher noted a progressive history of weakness and stiffness in his legs and in ambulating. His gait had been progressively more unsteady for the past 6-12 months. He noted nocturia xs I or 2. There was a history of a subtotal gastrectomy for duodenal ulcer five years prior to admission.

On examination, the patient was a well-developed, well-nourished, white male without significant general physical abnormality. Neurologically, there was some limitation of movement of the neck with limitation to liyperexteiision of the cervical spiiie. His hair was a salt-and-pepper white with blue eyes. On neurological examination, cranial nerves were intact. On motor examination, the patient showed a distinct paraparesis with increased tone. Reflexes were hyperactive in the lower extremities. There were bilateral extensor plantar responses. Sensory exam revealed a diminution of vibration and position sense in both the toes and ankles without a significant abnormality in pinprick or temperature or light touch sensation. The gait was wide-based and scissoring. The Romberg test was positive.

1. Difficulty with tandem walking may be seen in:

(a) lesions of the corticospinal pathway

(b) lesions of the cerebellum (e) hysteria (d) all of the above

2. The Romberg test is best examined wheii:

(a) the patient stands with his feet together and eyes open (b) his feet together and eyes closed (e) His feet placed one foot apart and eyes open (d) the feet placed one foot apart and eyes closed

3. The neurological deficits in this patient result from lesions in:

(a) the basal ganglia (b) the peripheral nerves (e) the spinal cord (d) the neuromuscular junction

4. Laboratory tests which would be helpful in further evaluation of this patient rank in order of preference:

(a) cervical inyelography (b) FTA-ABS test (c) folate and B12 level (d) cervical and lumbosacral spine x-rays

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Spiiial Cord Disorders Arthur Ericsson, M.D. Case 2 This 32 year old black female nurse was in excellent health, suffering from an occasional migraine headache, until approximately 7 days prior to admission. On lifting a patient, she experienced sudden pain from her lower back radiating to her right hip. During the ensuing 8 hours she developed progressive stiffness of her lower back so that she was unable to work without taking analgesics. The following day she was unable to work and experienced significantly increased pain when she moved rapidly, bent forward, or coughed.

On examination, general physical examination was normal. Neurological examination revealed that the cranial nerves were intact. Motor exam revealed definite weakness of the extensors of the right foot, the extensor hallucis longus and evertors of the right foot. Iteflexes were normal except for an absent right ankle jerk. The plantar responses were flexor. Sensory exam revealed minimal pinprick loss over the great toe on the right. There was marked spasm of the erector spinae muscles and limitation to any movement of the spine.

5. On the basis of the history and findings so far, the lesion most likely involves:

(a) the pyramidal tract (b) the thoracic spinal cord (e) lumbosacral roots (d) peripheral nerves

6. The chief diagnostic possibilities include;

(a) sickle cell anemia with iiifarctioti of the spinal cord (b) multiple sclerosis (c) tumor of the cauda equina (d) herniated disc of L5-Si

7. The diagnostic tests rank in order of importance:

(a) lumbar myelogram (b) CBC with sickle test (c) lumbosacral spine x-rays (d) electroniyogram and nerve conduction studies

8- The most common area of a ruptured iiitervertebral disc is:

(a) L-l-L2 and L2-L3 (b) T-1, T2 and T3-T4 (e) C5-c6 (d) L5-SI

9. The most common finding in a ruptured disc is:

(a) weakness in the distribution of the root

(b) moiioiieuritis (c) peripheral neuropathy (d) spastic paraparesis

10. The electromyogram in this case is most likely:

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Neurology Syllabus Elective Reading (a) abnormal, demonstrating a delayed conduction (b) abnormal, with frequent fibrillations and complex motor units (e) normal (d) none of the above Case 3 A 47 year old business executive suddenly experienced pain in his chest, radiating to his back in the midthoracic region, lasting approximately 20 minutes while having lunch. When he attempted to arise from the table, he collapsed, and after about an hours rest, was able to proceed normally. The following day, while at breakfast, he developed another episode of pain and weakness in the lower extremities. This, however, did not reverse.

On admission to the hospital, his B/P is noted to be 160/100. Pulse is 88 and respiration is 16. His general physical examination reveals no essential abnormalities. Neurological examination reveals the cranial nerves to be intact. Motor examination reveals a paraparesis with increased tone in both lower extremities. Palpation of the bladder reveals it to be enlarged and catheterization produces 800ce of urine. Reflexes in the lower extremities are slightly increased with bilateral extensor plantar responses noted. Sensory exam reveals minimal but definite decrease in pinprick sensation and light touch to extend vaguely to about T9 on the right and T8 on the left.

11. The most likely diagnosis in this case is:

(a) an acute extraiiiedullary spinal cord tumor

(b) multiple sclerosis (c) spinal cord infaretion (d) ruptured disc

12. Tile diagnostic tests in rank order of preference are:

(a) CBC and serology (b) cervical and thoracic myelography (e) EKG (d) chest x-ray (e) aortograpliy

13. The sudden severe paiii radiating to the iiiid-tlioracic area is most likely:

(a) Lightning paiii from tabes (b) A dissecting thoracic aneurysm (e) Lhermette's - seen in multiple sclerosis (d) None of the above

14. The loss of position and vibration which occurs in spinal cord lesions is due to:

(a) Lesion in the posterior column (b) Lesion in the spinocerebellar tract (c) Lesion in the spinothalamic tracts (d) None of the above

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Spinal Cord Disorders Arthur Ericsson, M.D. 15. A positive Babinski's sign indicates:

(a) That the lesion must be in the cerebral cortex (b) That the damage must involve the corticospinal tract or cells (e) That the damage must be in the internal capsule (d) That the lesion must be in the spinal cord

16.9 Spinal Cord Disorders: Answers

1. D 2. B 3. C 4. C,B,D,A 5. C 6. D 7. B,C,D,A 8. D 9. A 10. B 11, c 12, A,C,D,E,B 13, B

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