Conus Medullaris

Research & Review: Management of Cardiovascular and Orthopedic Complications Volume 1 Issue 1

Conus Medullaris

S. Sreeremya Assistant Professor, Department of Biotechnology, Sree Narayana Guru College, Coimbatore, Tamil Nadu, India Email: [email protected]

Abstract Conus Medullaris is the tapered end of spinal cord (CM). The anomalies in the L1-L2 region results in the malfunction and then it is termed Conus Medullaris syndrome (CMS). This paper covers the major aspect of CMS.

Keywords-CMS, L1-L2, Anomalies, Spinal cord

INTRODUCTION syndrome, posterior cord syndrome, and Conus Medullaris syndrome (CMS) caudaequina syndrome [1]. While CMS is majorly arises from a spectrum of clinico- associated with pathophysiologic pathologic entities representing disruption isolated to the Conus dysfunction of the lowest level of the Medullaris, it may also be associated with spinal cord termed the Conus Medullaris, a widespread spinal cord process which which consists of the sacral segments. includes the Conus Medullaris, which There is a subset of spinal cord injuries paves to the generalized syndromic clinically referred to as spinal cord injury symptoms. As per anatomy it is an illness syndromes, to which Conus Medullaris characterized by both upper motor and syndrome belongs, that are grouped by lower motor neuron signs and symptoms their respective symptomatology, that manifest in the perineal region and encompassing central cord syndrome, lower extremities [2]. Brown-Sequard syndrome, anterior cord

Fig: 1. Conus Medullaris

Research & Review: Management of Cardiovascular and Orthopedic Complications Volume 1 Issue 1

ARTICULATED ANOMALIES Conus Medullaris syndrome manifest Conus Medullaris Syndrome symptoms that are much similar to cauda  Spinal Cord Injury equina syndrome, but the two conditions  Brain Injury require different treatment. Conus Medullaris typically generates sudden Conus Medullaris Syndrome symptoms on both sides of the body, while The Conus Medullaris is the bundled, cauda equina syndrome usually develops tapered end of the spinal cord nerves (Fig: over time, synthesizing uneven symptoms 1). Situated specific near the first two concentrated on one side of the body. lumbar vertebrae, the Conus Medullaris Some other criteria that can help you and much specifically ends at the caudaequina, your care team differentiate one from the a bundle of spinal nerves and nerve roots. other include [5] Gradually, problems with the Conus  Cauda equina specifically causes Medullaris often affect the cauda equina. severe pain, while Conus Medullaris Conus Medullaris syndrome is a secondary results in mild to moderate pain, if any form of spinal cord damage resulting from pain at all is present. injuries to the lumber vertebrae [3]. Conus  Conus Medullaris can be mainly Medullaris syndrome is a type of caused by an injury, lesion, or incomplete spinal cord injury that isvery infection, while cauda equina is almost less likely to cause paralysis than many always caused by a lesion or infection. other types of spinal cord injuries. Instead,  Cauda equina may eliminate the the most usual symptomsinclude [4] patellar and Achilles reflexes, while  Severe back pain Conus Medullaris typically only  Strange or jarring sensations typically interferes with the Achilles reflex. in the back, such as buzzing, tingling,  Conus Medullaris is more likely than or numbness cauda equina to result in pain  Bowel and bladder dysfunction, such concentrated in the lower back. as difficulty controlling once  Impotence is much common with elimination functions Conus Medullaris than cauda equina.  Sexual dysfunction  Weakness, numbness, or tingling in TREATMENT FOR CONUS your lower limbs MEDULLARIS SYNDROME  Sensations in once lower limbs that To diagnose one with Conus Medullaris aren't caused by a clinical issue. For syndrome, your doctor may conduct MRI instance, you might have itchiness in imaging of your lower back and spine. your leg that is not well-explained by Treatment varies, and depends on the an allergic reaction or other issue. cause of the injury as well as its extent. Spinal decompression surgery often aids, MAJOR CAUSES OF CONUS and if a physical impediment to function MEDULLARIS SYNDROME remains—such as a tumor or the remnants Conus Medullaris syndrome isn't a disease of a bullet—your doctor may remove these in its own right sense, but rather it is the to restore spinal function. Radiation may product of a spinal trauma. In most cases, help if your symptoms are due to cancer. a blow to the back—such as from a car And if an infectionis caused by the accident or gunshot—is to blame. But symptoms, or injury is so severe it led to some diseases, mainly spinal cord an infection, you may need intravenous or infections, malformations of the spinal oral antibiotics. One will likely also need column due to spinal stenosis, and spinal physical therapy to regain function [6]. tumors can also cause the syndrome.

Research & Review: Management of Cardiovascular and Orthopedic Complications Volume 1 Issue 1

Conus Medullaris vascular malformations good subjective recovery, after analysis occupy a special very place in the and demonstrated mild objective classification of spinal vascular improvement also [8] malformations, because of both the location and complex angio-architecture. ANATOMY Historically, spinal vascular malformations The spinal cord, which is the downward or anomalies have been treated surgically continuation typically of medulla that and/or by endovascular embolization with starts just below the foramen magnum, glue with an ever increasing trial of the providesas a conduit for the ascending and new embolic agent Onyx, which is descending fiber tracts that connect the endowed with many desirable properties peripheral and spinal nerves to thebrain. [7]. The cord projects 31 pairs of spinal nerves on either side (8 cervical, 12 thoracic, 5 CASE-STUDIES lumbar, 5 sacral, 1coccygeal) that are A 19-year-old male presented with history articulated to the peripheral nerves [9]. A of pain and weakness in both the lower cross-section of the spinal cord reveals limbs of one year duration and bladder and butterfly-shaped gray matter in the middle, bowel disturbances of nine months surrounded by white matter. As in the duration. On examination, the patient had cerebrum, the gray matter is composed of mixed upper and lower motor neuron signs cell bodies. The white matter comprises of with power of 2/5 in both the lower limbs. various ascendingand descending tracts of MR imaging and after analysis revealed myelinated axon fibers, each with specific T2W hyperintensity in the lower cord with functions.During the development state, multiple vascular flow voids. Spinal digital the vertebral column grows more rapidly subtraction angiography specifically than the spinal cord. Spinal nerves exit the revealed conusarterio-venous vertebralcolumn at gradually more oblique malformation (AVM) with supply majorly angles because of the increasing distance from the anterior spinal axis contributed between the spinal cordsegments and the by the right ninth dorsal (RD9) radiculo- corresponding vertebrae. Lumbar and medullary artery and minor supply from sacral nerves travel nearly vertically down the posterior spinal artery contributed by the spinal canaltotypically reach their right eleventh dorsal (RD11) and right first exiting foramen.The spinal cord ends at lumbar (RL1) level. Endovascular the intervertebral disc between the first embolization was also performed via the and second lumbar vertebrae as a tapered RD9 contributor after super selective structure named Conus Medullaris, catheterization with Ultraflow micro- consisting of sacral spinal cord segments. catheter and injecting 0.6 mL of Onyx 18 The upper border of the Conus Medullaris into the most distal aspect of the feeder is often not well described. The fibrous just proximal to the prime fistula with extension of the cord, the filum terminale, good penetration of the Onyx into the is a non-neural element that extends down complex AVM and also filling the to the coccyx. The cauda equina (CE) is a draining veins typically up to some bundle of intradural nerve roots distance achieving complete AVM specifically at the end of the spinal cord, in obliteration with preservation of normal the subarachnoidspace distal to the Conus vessel. MRI done on second day post- Medullaris. Cauda is Latin for tail, and procedure showed complete resolution of equina is Latin for horse (ie, the "horse's the dilated flow voids, and T2 tail").The CE garners sensory innervation hyperintense signal had decreased. On day to the saddle area, motor innervation to the 1 post-procedure, the patient was reported sphincters, and parasympathetic

Research & Review: Management of Cardiovascular and Orthopedic Complications Volume 1 Issue 1

innervation to the bladder and lower bowel symptoms and signs in the dermatomes (ie, from the left splenic flexure to the and myotomes of the affected segments. rectum).The nerves in the CE region On the other hand, a cauda equina lesion is encompass lower lumbar and all of the an LMN lesion becausetypically the nerve sacral nerve roots. The pelvic splanchnic roots are part of the PNS. Cauda equina nerves mainly carry preganglionic syndrome may result from any lesion that parasympathetic fibers from S2-S4 to compresses CE nerve roots. These nerve innervate the detrusor muscle of the roots arespecifically susceptible to injury, urinary bladder. Conversely, somatic since they have a poorly developed lower motor neurons from S2-S4 innervate epineurium. A well-developed epineurium, the specific voluntary muscles of the asperipheral nerves, protects against external analsphincter and the urethral compressive and tensile stresses. The sphincter via the inferior rectal and the microvascular systems of the nerve roots perineal branches of the pudendal nerve, have a region of relative hypovascularity respectively. The nerve roots in the CE in their proximal third. Aggrandized region carry sensations from the lower vascular permeability and subsequent extremities, perineal dermatomes, and diffusion from the surrounding cerebral outgoing motor fibers to the lower spinal fluid supplement the extremity myotomes. The Conus nutritionalsupply. This property of Medullaris obtains its prime channel of aggrandized permeability may be related bloodsupply from 3 spinal arterial vessels: to the tendency toward edema formation of the anterior medianlongitudinal arterial the nerve roots, which may result in edema trunk and 2 postero-lateral trunks. Less compounding initial and sometimes prominent sources of blood supply include seemingly slight injury.Various studies in radiculararterial branches from the aorta, different animal models have assessed the lateral sacral arteries, and the fifth lumbar, pathophysiology of cauda equina iliolumbar, and middle sacral arteries [10] syndrome. Despite this, even the pressure as high as 200 mm Hgfailed tocompletely CAUDA EQUINA AND CONUS shut off nutritional supply to the CE. This MEDULLARIS SYNDROMES analysis showed that not only the The latter contribute more to the vascular magnitude but also the length and the supply of cauda equina, although not in a speed of obstruction were alsoimportant in segmental fashion, unlikethe blood supply damaging the CE region. Similar results to the peripheral nerves.The nerve roots were reported in other studies. It was may also be supplied typically by diffusion reported adecrease in blood flow to the from the surrounding CSF. Moreover, a intermediate nerve segment when 2 proximal area of thenerve roots may have pressure points were applied along the a zone of relative hypo-vascularity [11]. path ofthe nerve in the CE.Others have studied compound action potentials in PATHOPHYSIOLOGY afferent and efferent segments of nerves in In understanding the pathological basis of the CE region afterapplication of balloon any disease involving and encompassing compression.These scientist and the Conus Medullaris, keep in mind that researchers reported that 0-50 mmHg of thisstructure constitutes part of the spinal pressure did notaffect the action potentials cord (the distal part of the cord) and is in (the threshold for disturbances in action proximity to the nerve roots. Thus, injuries potentials was 50-75 mmHg), and to thisspecific area often yield a significantdeficits were observed when combination of upper motor neuron pressure rose to 100-200 mmHg[12]. (UMN) and lower motor neuron (LMN)

Research & Review: Management of Cardiovascular and Orthopedic Complications Volume 1 Issue 1

ETIOLOGY Deep venous thrombosis of the spinal Cauda equina syndrome is mainly caused veins (propagated) Inferior vena cava by any narrowing of the spinal canal that thrombosis A retrospective study of 66 compresses the nerve roots below thelevel consecutive cases of patients admitted to a of the spinal cord. Numerous causes of neurosurgical unit with suspected cauda cauda equina syndrome have been reported equina syndrome found that almost half and assessed, including discherniation, had no evidence of structural pathology on intradural disc rupture, spinal stenosis MRI. These researchers suggested that the secondary to other spinal conditions, symptoms have a functional origin in such traumatic injury, primary tumors such as cases [16] ependymomas and schwannomas, metastatic tumors, infectious conditions, TRAUMA arterio venousmal formation or Traumatic events leading to fracture or haemorrhage, and iatrogenic injury [13]. subluxation can lead to compression of the The main causes of cauda equina and cauda equina. Penetrating trauma can Conus Medullaris syndromes are the cause damage or typical compression of following: the cauda equina. Spinal manipulation 1. Lumbar stenosis (multilevel) resulting insubluxation has caused cauda 2. Spinal trauma including fractures equina syndrome [17]. Rare cases of sacral Herniated nucleus pulposus (cause of 2- insufficiency fractures have been assessed 6% of cases of caudaequina syndrome) and reported to cause cauda equina Neoplasm, including metastases, syndrome. Acute and delayed astrocytoma, neurofibroma, and presentations of CES due to hematomas meningioma; 20% of all spinal tumors andposttraumatic arachnoid cysts have mainly affect this area Spinal also been evaluated of cases of herniated infection/abscess (eg, tuberculosis, herpes disks leading to cauda equina syndrome, simplex virus, meningitis, meningo 76% occur in patients with a history of vascular syphilis, cytomegalovirus, chronic lowback pain; in 30%, cauda schistosomiasis) [14] equina syndrome is the first symptom of  Cauda Equina and Conus Medullaris lumbar disk herniation.Men in the Syndromesthe anesthetic agent (eg, fourthand fifth decades of life are mainly hyperbaric lidocaine, tetracaine) prone to cauda equina syndrome secondary  Spina bifida and subsequent tethered to disk herniation. Most cases of cauda cord syndrome equina syndrome secondary to disk herniation involve either a large central Other, rare causes include the following: disc or anextruded disc fragment that Spinal hemorrhage, especially subdural compromises a significant amount of the and epidural hemorrhage causing the spinal canal diameter [18]. The compression within the spinal canal presentationmay be acute or that of a much intravascular lymphomatosis Congenital more protracted course, with the latter anomalies of the spine/filumterminale, bearing a better prognosis. Individuals including [15] with congenital stenosis who sustain a disk  Tethered cord syndrome herniation are more likely to develop  Conus Medullaris lipomas cauda equina syndrome.  Multiple sclerosis  Spinal arteriovenous malformations The Conus Medullaris, which is the terminal segment of adult spinal cord, lies  Late-stage ankylosing spondylitis at the inferior aspect of the L1 vertebrae.  Neurosarcoidosis The segment above the conusis

Research & Review: Management of Cardiovascular and Orthopedic Complications Volume 1 Issue 1

specifically termed the epiconus, compression. An experimental study consisting of spinal cord segments L4-S1. on the pig cauda equina with special Lesions of the epiconus will affect the reference to differences in effects lower lumbar roots supplyingthe muscles between rapid and slow onset of of the lower part of the leg and foot, with compression. Spine (Phila Pa 1976). sparing of reflex function of sacral Jun 1989;14(6):569-73. segments. The bulbocavernosus reflex 5. Olmarker K, Rydevik B, Holm S, (i.e., reflex contraction of the anal Bagge U. Effects of experimental sphincter in response to the compression graded compression on blood flow in of the glans penis or clitoris) and spinal nerve roots. A vital microscopic micturition reflexes are preserved, study on the porcine cauda equina. J representing an upper motor neuron Orthop Res. 1988;7(6):817- 23. (UMN) or suprasacral lesion. Spasticity 6. Olmarker K, Holm S, Rydevik B. will most likely develop in thesacral Importance of compression onset rate innervated segments (toe flexors, ankle for the degree of impairment of plantarflexors, and hamstring muscles). impulse propagation in experimental Recovery is similar to other UMN compression injury of the porcine SCIs[19] cauda equina. Spine (Phila Pa 1976). May 1992;15(5):416-9. CONCLUSION 7. Olmarker K, Holm S, Rosenqvist AL, Conus Medullaris syndrome is a typically Rydevik B. Experimental nerve root secondary form of spinal cord damage compression. A model of acute, graded resulting from injuries to the lumber compression of the porcine cauda vertebrae. Lesion in the specific area or equina and an analysis of neural and anomalies in the (L1-L2) region cause vascular anatomy. Spine (Phila Pa serious distortions. This paper discusses 1976). Jan 1993;16(1):61-9. the characteristics of CMS. 8. Metser U, Lerman H, Blank A, Lievshitz G, Bokstein F, Even-Sapir E. REFERENCES Malignant involvement of the spine: 1. Mauffrey C, Randhawa K, Lewis C, assessment by 18F-FDG PET/CT. J Brewster M, Dabke H. Cauda equina Nucl Med. Feb 2004;45(2):279-84 syndrome: an anatomically driven 9. Spetzler RF, Detwiler PW, Riina HA, review. Br J Hosp Med (Lond). Jun Porter RW. Modified classification of 2008;69(6):344-7. spinal cord vascular lesions. J 2. Olmarker K, Rydevik B, Hansson T, Neurosurg Spine 2002;96:145-56. Holm S. Compression-induced 10. Carlson AP, Taylor CL, Yonas H. changes of the nutritional supply to the Treatment of duralarteriovenous fistula porcine cauda equina. J Spinal Disord. using ethylene vinyl alcohol (Onyx) Mar 1990;3(1):25-9. arterial embolization as the primary 3. Delamarter RB, Sherman JE, Carr JB. modality: Short-term results. J 1991 Volvo Award in experimental Neurosurg 2007;107:1120-5. studies. Cauda equine syndrome: 11. Van Rooji WJ, Sluzewski M, Beute neurologic recovery following GN. Brain AVM embolization with immediate, early, or late Onyx. AJNR Am J Neuroradiol decompression. Spine (Phila Pa 1976). 2007;28:172-7. Sep 1991;16(9):1022-9. 12. Molyneux AJ, Coley SC. Embolization 4. Olmarker K, Rydevik B, Holm S. of spinal cord arteriovenous Edema formation in spinal nerve roots malformations with an ethylene vinyl induced by experimental, graded alcohol copolymer dissolved in

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