Sections

Cauda Equina and Conus Medullaris Syndromes

Sections Cauda Equina and Conus Medullaris Syndromes
Overview
Presentation
DDx
Workup
Treatment
Medication
Questions & Answers
Media Gallery
Tables
References

Presentation

History

Patients can present with symptoms of isolated cauda equina syndrome, isolated conus medullaris syndrome, or a combination. The symptoms and signs of cauda equina syndrome tend to be mostly lower motor neuron (LMN) in nature, while those of conus medullaris syndrome are a combination of LMN and upper motor neuron (UMN) effects (see Table 1, below). The history of onset, the duration of symptoms, and the presence of other features or symptoms could point to the possible causes.

Table 1. Symptoms and Signs of Conus Medullaris and Cauda Equina Syndromes (Open Table in a new window)

	Conus Medullaris Syndrome	Cauda Equina Syndrome
Presentation	Sudden and bilateral	Gradual and unilateral
Reflexes	Knee jerks preserved but ankle jerks affected	Both ankle and knee jerks affected
Radicular pain	Less severe	More severe
Low back pain	More	Less
Sensory symptoms and signs	Numbness tends to be more localized to perianal area; symmetrical and bilateral; sensory dissociation occurs	Numbness tends to be more localized to saddle area; asymmetrical, may be unilateral; no sensory dissociation; loss of sensation in specific dermatomes in lower extremities with numbness and paresthesia; possible numbness in pubic area, including glans penis or clitoris
Motor strength	Typically symmetric, hyperreflexic distal paresis of lower limbs that is less marked; fasciculations may be present	Asymmetric areflexic paraplegia that is more marked; fasciculations rare; atrophy more common
Impotence	Frequent	Less frequent; erectile dysfunction that includes inability to have erection, inability to maintain erection, lack of sensation in pubic area (including glans penis or clitoris), and inability to ejaculate
Sphincter dysfunction	Urinary retention and atonic anal sphincter cause overflow urinary incontinence and fecal incontinence; tend to present early in course of disease	Urinary retention; tends to present late in course of disease

Symptoms of cauda equina syndrome include the following:

Low back pain
Unilateral or bilateral sciatica
Saddle and perineal hypoesthesia or anesthesia
Bowel and bladder disturbances
Lower extremity motor weakness and sensory deficits
Reduced or absent lower extremity reflexes

Low back pain can be divided into local and radicular pain. Local pain is generally a deep, aching pain resulting from soft-tissue and vertebral body irritation. Radicular pain is generally a sharp, stabbing pain resulting from compression of the dorsal nerve roots. Radicular pain projects in dermatomal distributions. Low back pain in cauda equina syndrome may have some characteristic that suggests something different from the far more common lumbar strain. Patients may report severity or a trigger, such as head turning, that seems unusual.

Severe pain is an early finding in 96% of patients with cauda equina syndrome secondary to spinal neoplasm. Later findings include lower extremity weakness due to involvement of the ventral roots. Patients generally develop hypotonia and hyporeflexia. Sensory loss and sphincter dysfunction are also common.

Urinary manifestations of cauda equina syndrome include the following:

Retention
Difficulty initiating micturition
Decreased urethral sensation
Typically, urinary manifestations begin with urinary retention and are later followed by an overflow urinary incontinence.

Bell et al demonstrated that the accuracy of urinary retention, urinary frequency, urinary incontinence, altered urinary sensation, and altered perineal sensation as indications of possible disk prolapse justified urgent MRI assessment.^{[76, 77]}

Bowel disturbances may include the following:

Incontinence
Constipation
Loss of anal tone and sensation

The initial presentation of bladder/bowel dysfunction may be of difficulty starting or stopping a stream of urine. It may be followed by frank incontinence, first of urine then of stool. The urinary incontinence is on the basis of overflow. It is usually with associated saddle (perineal) anesthesia (the examiner can inquire if toilet paper feels different when the patient wipes).

Physical Examination

The symptoms of cauda equina syndrome are associated with corresponding signs pointing to an LMN or UMN lesion. Refer to the images and tables below for assistance in examining the patient and documenting examination findings. In addition to the signs listed below, signs of other possible causes should be sought (eg, examination of the peripheral pulses to rule out possible vascular cause or ischemia of the conus medullaris).

Muscle groups, surface anatomy, peripheral sensory innervation, and dermatomes of the anterior lower limb. This image should be correlated with Tables 1 and 2 in the text. Image courtesy of Nicholas Y. Lorenzo, MD.

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Muscle groups, surface anatomy, peripheral sensory innervation, and dermatomes of the posterior lower limb. This image should be correlated with Tables 1 and 2 in the text. Image courtesy of Nicholas Y. Lorenzo, MD.

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Pain and deficits associated with nerve root involvement are shown in Table 2, below.

Table 2. Pain and Deficits Associated with Specific Nerve Roots (Open Table in a new window)

Nerve Root	Pain	Sensory Deficit	Motor Deficit	Reflex Deficit
L2	Anterior medial thigh	Upper thigh	Slight quadriceps weakness; hip flexion; thigh adduction	Slightly diminished suprapatellar
L3	Anterior lateral thigh	Lower thigh	Quadriceps weakness; knee extension; thigh adduction	Patellar or suprapatellar
L4	Posterolateral thigh, anterior tibia	Medial leg	Knee and foot extension	Patellar
L5	Dorsum of foot	Dorsum of foot	Dorsiflexion of foot and toes	Hamstrings
S1-2	Lateral foot	Lateral foot	Plantar flexion of foot and toes	Achilles
S3-5	Perineum	Saddle	Sphincters	Bulbocavernosus; anal

Table 3. Root and Peripheral Nerve Innervation of the Lumbosacral Plexus (Open Table in a new window)

Muscle	Nerve	Root
Iliopsoas	Femoral	L2, 3, 4
Adductor longus	Obturator	L2, 3, 4
Gracilis	Obturator	L2, 3, 4
Quadriceps femoris	Femoral	L2, 3, 4
Anterior tibial	Deep peroneal	L4, 5
Extensor hallucis longus	Deep peroneal	L4, 5
Extensor digitorum longus	Deep peroneal	L4,5
Extensor digitorum brevis	Deep peroneal	L4, 5, S1
Peroneus longus	Superficial peroneal	L5, S1
Internal hamstrings	Sciatic	L4, 5, S1
External hamstrings	Sciatic	L5, S1
Gluteus medius	Superior gluteal	L4, 5, S1
Gluteus maximus	Inferior gluteal	L5, S1, 2
Posterior tibial	Tibial	L5, S1
Flexor digitorum longus	Tibial	L5, S1
Abductor hallucis brevis	Tibial (medial plantar)	L5, S1, 2
Abductor digiti quinti pedis	Tibial (lateral plantar)	S1, 2
Gastrocnemius lateral	Tibial	L5, S1, 2
Gastrocnemius medial	Tibial	S1, 2
Soleus	Tibial	S1, 2

Pain often is localized to the low back; local tenderness to palpation or percussion may be present. Pain in the legs (or radiating to the legs) is characteristic of cauda equina syndrome. Radicular pain is a common presentation in patients with cauda equina syndrome, usually in association with radicular sensory loss (saddle anesthesia), asymmetric paraplegia with loss of tendon reflexes, muscle atrophy, and bladder dysfunction. The presentation is somewhat similar to and is often confused with conus and epiconus lesions.

Reflex abnormalities may be present; they typically include loss or diminution of reflexes. Hyperactive reflexes may signal spinal cord involvement and exclude the diagnosis of cauda equina syndrome. Sensory abnormality may be present in the perineal area or lower extremities. Light touch in the perineal area should be tested. Anesthetic areas may show skin breakdown.

Muscle weakness may be present in muscles supplied by affected roots. Muscle wasting may occur in chronic cauda equina syndrome.

Poor anal sphincter tone is characteristic of cauda equina syndrome. Babinski sign or other signs of upper motor neuron involvement suggest a diagnosis other than cauda equina syndrome, possibly spinal cord compression.

In cauda equina syndrome, the peripheral nerve fibers from the sacral segments of the cord, as well as various lumbar dorsal and ventral nerve roots, may also be involved. This results in an asymmetric and higher distribution of motor and sensory symptoms and signs in the lower extremities. Incontinence of bowel and bladder is not severe and develops late for the same reason.

In conus and epiconus lesions, the sacral region neurons (S2-S4) are destroyed. The destruction of these neurons leads to an early and more severe involvement of bowel, urinary bladder, and sexual dysfunction than seen in those with CES. In contrast, for the same reason, the motor and sensory symptoms in the lower extremities are often not very severe and only the distal parts of the limb musculature are involved.

The anatomical proximity of the conus medullaris, the epiconus, and the cauda equina can lead to 2 of these anatomical structures being involved via a single lesion, resulting in an overlap of symptomatology.

The salient features and findings of cauda equina syndrome and conus medullaris syndrome are listed in Table 4, below.

Table 4. Cauda Equina Versus Conus Medullaris Syndrome (Open Table in a new window)

Features	Cauda Equina Syndrome	Conus Medullaris
Vertebral level	L2-sacrum	L1-L2
Spinal level	Injury to the lumbosacral nerve roots	Injury of the sacral cord segment (conus and epiconus) and roots
Severity of symptoms and signs	Usually severe	Usually not severe
Symmetry of symptoms and signs	Usually asymmetric	Usually symmetric
Pain	Prominent, asymmetric, and radicular	Usually bilateral and in the perineal area
Motor	Weakness to flaccid paralysis	Normal motor function to mild or moderate weakness
Sensory	Saddle anesthesia, may be asymmetric	Symmetric saddle distribution, sensory loss of pin prick, and temperature sensations (Tactile sensation is spared.)
Reflexes	Areflexic lower extremities; bulbocavernosus reflex is absent in low CE (sacral) lesions	Areflexic lower extremities (If the epiconus is involved, patellar reflex may be absent, whereas bulbocavernosus reflex may be spared.)
Sphincter and sexual function	Usually late and of lesser magnitude; lower sacral roots involvement can cause bladder, bowel, and sexual dysfunction	Early and severe bowel, bladder, and sexual dysfunction that results in a reflexic bowel and bladder with impaired erection in males
EMG	Multiple root level involvement; sphincters may also be involved	Mostly normal lower extremity with external anal sphincter involvement
Outcome	May be favorable compared with conus medullaris syndrome	The outcome may be less favorable than in patients with CES

Cauda equina syndrome

In cauda equina syndrome, muscle strength in the lower extremities is diminished. This may be specific to the involved nerve roots as listed below, with the lower lumbar and sacral roots more affected, leading to diminished strength in the glutei muscles, hamstring muscles (ie, semimembranosus, semitendinosus, biceps femoris), and the gastrocnemius and soleus muscles.

Sensation is decreased to pinprick and light touch in a dermatomal pattern corresponding to the affected nerve roots. This includes saddle anesthesia (sometimes including the glans penis or clitoris) and decreased sensation in the lower extremities in the distribution of lumbar and sacral nerves. Vibration sense may also be affected. Sensation of the glans penis or clitoris should be examined.

Muscle stretch reflexes may be absent or diminished in the corresponding nerve roots. Babinski reflex is diminished or absent.

Bulbocavernosus reflexes may be absent or diminished. This should always be tested.

Anal sphincter tone is patulous and should always be tested since it can define the completeness of the injury (with bulbocavernosus reflex); it is also useful in monitoring recovery from the injury.

Urinary incontinence could also occur secondary to loss of urinary sphincter tone; this may also present initially as urinary retention secondary to a flaccid bladder.

Muscle tone in the lower extremities is decreased, which is consistent with an LMN lesion.

Conus medullaris syndrome

Patients may exhibit hypertonicity, especially if the lesion is isolated and primarily UMN.

Signs are almost identical to those of the cauda equina syndrome, except that in conus medullaris syndrome signs are more likely to be bilateral; sacral segments occasionally show preserved bulbocavernosus reflexes and normal or increased anal sphincter tone; the muscle stretch reflex may be hyperreflexic, especially if the conus medullaris syndrome (ie, UMN lesion) is isolated; Babinski reflex may affect the extensors; and muscle tone might be increased (ie, spasticity).

Other signs include papilledema (rare, occurs in lower spinal cord tumors), cutaneous abnormalities (eg, cutaneous angioma, pilonidal sinus that may be present in dermoid or epidermoid tumors), distended bladder due to areflexia, and other spinal abnormalities (noted on lower back examination) predisposing the patient to the syndrome.

Muscle strength

Physical examination for cauda equina or conus medullaris syndromes would be incomplete without tests for sensation of the saddle and perineal areas, bulbocavernosus reflex, cremasteric reflex, and anal sphincter tone, findings for all of which are likely to be abnormal.

Muscle strength of the following muscles should be tested to determine the level of lesion:

L2 - Hip flexors (iliopsoas)
L3 - Knee extensors (quadriceps)
L4 - Ankle dorsiflexors (tibialis anterior)
L5 - Big toe extensors (extensor hallucis longus)
S1 - Ankle plantar flexors (gastrocnemius/soleus)

ASIA impairment scale

In defining impairments associated with a spinal cord lesion, the American Spinal Cord Injury Association (ASIA) impairment scale is used in determining the level and extent of injury.

This scale should also be used in defining the extent of conus medullaris syndrome/cauda equina syndrome. The scale is as follows:

A - Complete; no sensory or motor function preserved in sacral segments S4-S5
B - Incomplete; sensory, but not motor, function preserved below the neurologic level and extends through sacral segments S4-S5
C - Incomplete; motor function preserved below the neurologic level, and the majority of key muscles below the neurologic level have a muscle grade less than 3
D - Incomplete; motor function preserved below the neurologic level, and the majority of key muscles below the neurologic level have a muscle grade greater than or equal to 3
E - Normal; sensory and motor function normal

The injury should be described using this scale, for example, ASIA class A. Most patients with cauda equina/conus medullaris syndrome are in ASIA class A or B initially and gradually improve to class C, D, or E.

Complications

Complications include the following:

Thromboembolic phenomena
Neurogenic bladder/bowel
Erectile dysfunction
Pressure ulcers
Heterotopic ossification
Osteoporosis
Chronic neuropathic pain
Spasticity/contractures
Recurrent urinary tract infections
Urethral stricture
Bladder calculi
Depression

Differential Diagnoses

Mauffrey C, Randhawa K, Lewis C, Brewster M, Dabke H. Cauda equina syndrome: an anatomically driven review. Br J Hosp Med (Lond). 2008 Jun. 69(6):344-7. [QxMD MEDLINE Link].
Rogers WK, Todd M. Acute spinal cord injury. Best Pract Res Clin Anaesthesiol. 2016 Mar. 30 (1):27-39. [QxMD MEDLINE Link].
Olmarker K, Rydevik B, Hansson T, Holm S. Compression-induced changes of the nutritional supply to the porcine cauda equina. J Spinal Disord. 1990 Mar. 3(1):25-9. [QxMD MEDLINE Link].
Delamarter RB, Sherman JE, Carr JB. 1991 Volvo Award in experimental studies. Cauda equina syndrome: neurologic recovery following immediate, early, or late decompression. Spine (Phila Pa 1976). 1991 Sep. 16(9):1022-9. [QxMD MEDLINE Link].
Olmarker K, Rydevik B, Holm S. Edema formation in spinal nerve roots induced by experimental, graded compression. An experimental study on the pig cauda equina with special reference to differences in effects between rapid and slow onset of compression. Spine (Phila Pa 1976). 1989 Jun. 14(6):569-73. [QxMD MEDLINE Link].
Olmarker K, Rydevik B, Holm S, Bagge U. Effects of experimental graded compression on blood flow in spinal nerve roots. A vital microscopic study on the porcine cauda equina. J Orthop Res. 1989. 7(6):817-23. [QxMD MEDLINE Link].
Olmarker K, Holm S, Rydevik B. Importance of compression onset rate for the degree of impairment of impulse propagation in experimental compression injury of the porcine cauda equina. Spine (Phila Pa 1976). 1990 May. 15(5):416-9. [QxMD MEDLINE Link].
Olmarker K, Holm S, Rosenqvist AL, Rydevik B. Experimental nerve root compression. A model of acute, graded compression of the porcine cauda equina and an analysis of neural and vascular anatomy. Spine (Phila Pa 1976). 1991 Jan. 16(1):61-9. [QxMD MEDLINE Link].
Metser U, Lerman H, Blank A, Lievshitz G, Bokstein F, Even-Sapir E. Malignant involvement of the spine: assessment by 18F-FDG PET/CT. J Nucl Med. 2004 Feb. 45(2):279-84. [QxMD MEDLINE Link].
Takahashi K, Olmarker K, Holm S, Porter RW, Rydevik B. Double-level cauda equina compression: an experimental study with continuous monitoring of intraneural blood flow in the porcine cauda equina. J Orthop Res. 1993 Jan. 11(1):104-9. [QxMD MEDLINE Link].
Rydevik BL, Pedowitz RA, Hargens AR, Swenson MR, Myers RR, Garfin SR. Effects of acute, graded compression on spinal nerve root function and structure. An experimental study of the pig cauda equina. Spine (Phila Pa 1976). 1991 May. 16(5):487-93. [QxMD MEDLINE Link].
Rydevik B. Neurophysiology of cauda equina compression. Acta Orthop Scand Suppl. 1993. 251:52-5. [QxMD MEDLINE Link].
Pedowitz RA, Garfin SR, Massie JB, et al. Effects of magnitude and duration of compression on spinal nerve root conduction. Spine (Phila Pa 1976). 1992 Feb. 17(2):194-9. [QxMD MEDLINE Link].
Todd NV. An algorithm for suspected cauda equina syndrome. Ann R Coll Surg Engl. 2009 May. 91(4):358-9; author reply 359-60. [QxMD MEDLINE Link]. [Full Text].
Olivero WC, Wang H, Hanigan WC, et al. Cauda equina syndrome (CES) from lumbar disc herniations. J Spinal Disord Tech. 2009 May. 22(3):202-6. [QxMD MEDLINE Link].
Kingwell SP, Curt A, Dvorak MF. Factors affecting neurological outcome in traumatic conus medullaris and cauda equina injuries. Neurosurgical Focus. 2008. 25(5):E7. [QxMD MEDLINE Link].
Fujisawa H, Igarashi S, Koyama T. Acute cauda equina syndrome secondary to lumbar disc herniation mimicking pure conus medullaris syndrome--case report. Neurol Med Chir (Tokyo). 1998 Jul. 38(7):429-31. [QxMD MEDLINE Link].
Raj D, Coleman N. Cauda equina syndrome secondary to lumbar disc herniation. Acta Orthop Belg. 2008 Aug. 74(4):522-7. [QxMD MEDLINE Link].
Gleave JR, MacFarlane R. Prognosis for recovery of bladder function following lumbar central disc prolapse. Br J Neurosurg. 1990. 4(3):205-9. [QxMD MEDLINE Link].
Gellido CL, Onesti S, Llena J. Spinal schistosomiasis. Neurology. 2000 Jan 25. 54(2):527. [QxMD MEDLINE Link].
Waters JH, Watson TB, Ward MG. Conus medullaris injury following both tetracaine and lidocaine spinal anesthesia. J Clin Anesth. 1996 Dec. 8(8):656-8. [QxMD MEDLINE Link].
Kothbauer K, Seiler RW. [Tethered spinal cord syndrome in adults]. Nervenarzt. 1997 Apr. 68(4):285-91. [QxMD MEDLINE Link].
Widge AS, Tomycz ND, Kanter AS. Sacral preservation in cauda equina syndrome from inferior vena cava thrombosis. J Neurosurg Spine. 2009 Mar. 10(3):257-9. [QxMD MEDLINE Link].
Rooney A, Statham PF, Stone J. Cauda equina syndrome with normal MR imaging. J Neurol. 2009 May. 256(5):721-5. [QxMD MEDLINE Link].
Harrop JS, Hunt GE Jr, Vaccaro AR. Conus medullaris and cauda equina syndrome as a result of traumatic injuries: management principles. Neurosurg Focus. 2004 Jun 15. 16(6):e4. [QxMD MEDLINE Link].
Fisher RG. Sacral fracture with compression of cauda equina: surgical treatment. J Trauma. 1988 Dec. 28(12):1678-80. [QxMD MEDLINE Link].
Schizas C, Ballesteros C, Roy P. Cauda equina compression after trauma: an unusual presentation of spinal epidural lipoma. Spine (Phila Pa 1976). 2003 Apr 15. 28(8):E148-51. [QxMD MEDLINE Link].
Thongtrangan I, Le H, Park J, Kim DH. Cauda equina syndrome in patients with low lumbar fractures. Neurosurg Focus. 2004 Jun 15. 16(6):e6. [QxMD MEDLINE Link].
Haldeman S, Rubinstein SM. Cauda equina syndrome in patients undergoing manipulation of the lumbar spine. Spine (Phila Pa 1976). 1992 Dec. 17(12):1469-73. [QxMD MEDLINE Link].
Muthukumar T, Butt SH, Cassar-Pullicino VN, McCall IW. Cauda equina syndrome presentation of sacral insufficiency fractures. Skeletal Radiol. 2007 Apr. 36(4):309-13. [QxMD MEDLINE Link].
Kebaish KM, Awad JN. Spinal epidural hematoma causing acute cauda equina syndrome. Neurosurg Focus. 2004 Jun 15. 16(6):e1. [QxMD MEDLINE Link].
Chen HJ, Liang CL, Lu K, Liliang PC, Tsai YD. Cauda equina syndrome caused by delayed traumatic spinal subdural haematoma. Injury. 2001 Jul. 32(6):505-7. [QxMD MEDLINE Link].
Zuccarello M, Powers G, Tobler WD, Sawaya R, Hakim SZ. Chronic posttraumatic lumbar intradural arachnoid cyst with cauda equina compression: case report. Neurosurgery. 1987 Apr. 20(4):636-8. [QxMD MEDLINE Link].
Raaf J. Removal of protruded lumbar intervertebral discs. J Neurosurg. 1970 May. 32(5):604-11. [QxMD MEDLINE Link].
Kostuik JP, Harrington I, Alexander D, Rand W, Evans D. Cauda equina syndrome and lumbar disc herniation. J Bone Joint Surg Am. 1986 Mar. 68(3):386-91. [QxMD MEDLINE Link].
Shapiro S. Cauda equina syndrome secondary to lumbar disc herniation. Neurosurgery. 1993 May. 32(5):743-6; discussion 746-7. [QxMD MEDLINE Link].
Shapiro S. Medical realities of cauda equina syndrome secondary to lumbar disc herniation. Spine (Phila Pa 1976). 2000 Feb 1. 25(3):348-51; discussion 352. [QxMD MEDLINE Link].
Ahn UM, Ahn NU, Buchowski JM, Garrett ES, Sieber AN, Kostuik JP. Cauda equina syndrome secondary to lumbar disc herniation: a meta-analysis of surgical outcomes. Spine (Phila Pa 1976). 2000 Jun 15. 25(12):1515-22. [QxMD MEDLINE Link].
Scott PJ. Bladder paralysis in cauda equina lesions from disc prolapse. J Bone Joint Surg. 1965. 47B:224-235.
Dinning TA, Schaeffer HR. Discogenic compression of the cauda equina: a surgical emergency. Aust N Z J Surg. 1993 Dec. 63(12):927-34. [QxMD MEDLINE Link].
Shaw M, Birch N. Facet joint cysts causing cauda equina compression. J Spinal Disord Tech. 2004 Oct. 17(5):442-5. [QxMD MEDLINE Link].
Ahn NU, Ahn UM, Nallamshetty L, et al. Cauda equina syndrome in ankylosing spondylitis (the CES-AS syndrome): meta-analysis of outcomes after medical and surgical treatments. J Spinal Disord. 2001 Oct. 14(5):427-33. [QxMD MEDLINE Link].
Tullous MW, Skerhut HE, Story JL, et al. Cauda equina syndrome of long-standing ankylosing spondylitis. Case report and review of the literature. J Neurosurg. 1990 Sep. 73(3):441-7. [QxMD MEDLINE Link].
Devlin GP, Sheppeard H. Cauda equina syndrome in ankylosing spondylitis diagnosed by computed tomography. N Z Med J. 1987 Oct 28. 100(834):651-2. [QxMD MEDLINE Link].
Rubenstein DJ, Ghelman B. Case report 477: Cauda equina syndrome (CES) complicating long-standing ankylosing spondylitis (AS). Skeletal Radiol. 1988. 17(3):212-5. [QxMD MEDLINE Link].
Indrieri RJ. Lumbosacral stenosis and injury of the cauda equina. Vet Clin North Am Small Anim Pract. 1988 May. 18(3):697-710. [QxMD MEDLINE Link].
Baba H, Maezawa Y, Furusawa N, Imura S, Tomita K. The role of calcium deposition in the ligamentum flavum causing a cauda equina syndrome and lumbar radiculopathy. Paraplegia. 1995 Apr. 33(4):219-23. [QxMD MEDLINE Link].
Schweitzer JS, Batzdorf U. Ependymoma of the cauda equina region: diagnosis, treatment, and outcome in 15 patients. Neurosurgery. 1992 Feb. 30(2):202-7. [QxMD MEDLINE Link].
Anderson JR, Gullan RW. Paraganglioma of the cauda equina: a case report. J Neurol Neurosurg Psychiatry. 1987 Jan. 50(1):100-3. [QxMD MEDLINE Link]. [Full Text].
Kagaya H, Abe E, Sato K, Shimada Y, Kimura A. Giant cauda equina schwannoma. A case report. Spine (Phila Pa 1976). 2000 Jan 15. 25(2):268-72. [QxMD MEDLINE Link].
Bagley CA, Gokaslan ZL. Cauda equina syndrome caused by primary and metastatic neoplasms. Neurosurg Focus. 2004 Jun 15. 16(6):e3. [QxMD MEDLINE Link].
Ampil FL, Mills GM, Burton GV. A retrospective study of metastatic lung cancer compression of the cauda equina. Chest. 2001 Nov. 120(5):1754-5. [QxMD MEDLINE Link].
Saad F, Clarke N, Colombel M. Natural history and treatment of bone complications in prostate cancer. Eur Urol. 2006 Mar. 49(3):429-40. [QxMD MEDLINE Link].
Natale M, Spennato P, Savarese L, Bocchetti A, Esposito S, Barbato R. Anaplastic oligodendroglioma presenting with drop metastases in the cauda equina. Clin Neurol Neurosurg. 2005 Aug. 107(5):417-20. [QxMD MEDLINE Link].
den Boon J, Avezaat CJ, van der Gaast A, Koops W, Huikeshoven FJ. Conus-cauda syndrome as a presenting symptom of endodermal sinus tumor of the ovary. Gynecol Oncol. 1995 Apr. 57(1):121-5. [QxMD MEDLINE Link].
Bourezgui M, Rafai MA, El Moutawakkil B, et al. [Cauda equina syndrome revealing neuroblastoma]. Rev Neurol (Paris). 2008 Dec. 164(12):1048-51. [QxMD MEDLINE Link].
Lenehan B, Sullivan P, Street J, Dudeney S. Epidural abscess causing cauda equina syndrome. Ir J Med Sci. 2005 Jul-Sep. 174(3):88-91. [QxMD MEDLINE Link].
Kapoor SK, Garg V, Dhaon BK, Jindal M. Tuberculosis of the posterior vertebral elements: a rare cause of compression of the cauda equina. A case report. J Bone Joint Surg Am. 2005 Feb. 87(2):391-4. [QxMD MEDLINE Link].
Faraj A, Krishna M, Mehdian SM. Cauda equina syndrome secondary to lumbar spondylodiscitis caused by Streptococcus milleri. Eur Spine J. 1996. 5(2):134-6. [QxMD MEDLINE Link].
Brecker SJ, Pugey CD. Nocardia asteroides infection of the cauda equina. J Neurol Neurosurg Psychiatry. 1988 Feb. 51(2):309-11. [QxMD MEDLINE Link]. [Full Text].
Donovan DJ, Polly DW Jr, Ondra SL. The removal of a transdural pedicle screw placed for thoracolumbar spine fracture. Spine (Phila Pa 1976). 1996 Nov 1. 21(21):2495-8; discussion 2499. [QxMD MEDLINE Link].
Rittmeister M, Leyendecker K, Kurth A, Schmitt E. Cauda equina compression due to a laminar hook: A late complication of posterior instrumentation in scoliosis surgery. Eur Spine J. 1999. 8(5):417-20. [QxMD MEDLINE Link].
Mineiro J, Weinstein SL. Delayed postoperative paraparesis in scoliosis surgery. A case report. Spine (Phila Pa 1976). 1997 Jul 15. 22(14):1668-72. [QxMD MEDLINE Link].
Ilias WK, Klimscha W, Skrbensky G, Weinstabl R, Widhalm A. Continuous microspinal anaesthesia: another perspective on mechanisms inducing cauda equina syndrome. Anaesthesia. 1998 Jul. 53(7):618-23. [QxMD MEDLINE Link].
Wera GD, Dean CL, Nho S, et al. Cauda equina syndrome resulting from treatment of dural ectasia with fibrin glue injection. J Spinal Disord Tech. 2006 Apr. 19(2):148-50. [QxMD MEDLINE Link].
Imran Y, Halim Y. Acute cauda equina syndrome secondary to free fat graft following spinal decompression. Singapore Med J. 2005 Jan. 46(1):25-7. [QxMD MEDLINE Link].
Johnson ME. Potential neurotoxicity of spinal anesthesia with lidocaine. Mayo Clin Proc. 2000 Sep. 75(9):921-32. [QxMD MEDLINE Link].
Loo CC, Irestedt L. Cauda equina syndrome after spinal anaesthesia with hyperbaric 5% lignocaine: a review of six cases of cauda equina syndrome reported to the Swedish Pharmaceutical Insurance 1993-1997. Acta Anaesthesiol Scand. 1999 Apr. 43(4):371-9. [QxMD MEDLINE Link].
Liu YC, Wu RS, Wong CS. Unexpected complication of attempted epidural anaesthesia: cauda equina syndrome. Anaesth Intensive Care. 2003 Aug. 31(4):461-4. [QxMD MEDLINE Link].
Pouchot J, Si-Hassen C, Damade R, Bayeux MC, Mathieu A, Vinceneux P. Cauda equina compression by epidural lipomatosis in obesity. Effectiveness of weight reduction. J Rheumatol. 1995 Sep. 22(9):1771-5. [QxMD MEDLINE Link].
Diaz JH. Permanent paraparesis and cauda equina syndrome after epidural blood patch for postdural puncture headache. Anesthesiology. 2002 Jun. 96(6):1515-7. [QxMD MEDLINE Link].
Prusick VR, Lint DS, Bruder WJ. Cauda equina syndrome as a complication of free epidural fat-grafting. A report of two cases and a review of the literature. J Bone Joint Surg Am. 1988 Sep. 70(8):1256-8. [QxMD MEDLINE Link].
Lambert DH. Bupivacaine spinal block cauda equina syndrome: why did it happen?. Anesthesiology. 2005 Jun. 102(6):1285-6; author reply 1287-8. [QxMD MEDLINE Link].
Shaw A, Anwar H, Targett J, Lafferty K. Cauda equina syndrome versus saddle embolism. Ann R Coll Surg Engl. 2008 Sep. 90(6):W6-8. [QxMD MEDLINE Link]. [Full Text].
O'Laughlin SJ, Kokosinski E. Cauda equina syndrome in a pregnant woman referred to physical therapy for low back pain. J Orthop Sports Phys Ther. 2008 Nov. 38(11):721. [QxMD MEDLINE Link].
Bell DA, Collie D, Statham PF. Cauda equina syndrome: what is the correlation between clinical assessment and MRI scanning?. Br J Neurosurg. 2007 Apr. 21(2):201-3. [QxMD MEDLINE Link].
Ma B, Wu H, Jia LS, Yuan W, Shi GD, Shi JG. Cauda equina syndrome: a review of clinical progress. Chin Med J (Engl). 2009 May 20. 122(10):1214-22. [QxMD MEDLINE Link].
Bardin LD, King P, Maher CG. Diagnostic triage for low back pain: a practical approach for primary care. Med J Aust. 2017 Apr 3. 206 (6):268-273. [QxMD MEDLINE Link].
Balzer JR, Rose RD, Welch WC, Sclabassi RJ. Simultaneous somatosensory evoked potential and electromyographic recordings during lumbosacral decompression and instrumentation. Neurosurgery. 1998 Jun. 42(6):1318-24; discussion 1324-5. [QxMD MEDLINE Link].
Mathew P, Todd NV. Diagnosis of intradural conus and cauda equina tumours. Br J Hosp Med. 1993 Aug 18-31. 50(4):169-70, 172-4. [QxMD MEDLINE Link].
Bell DA, Collie D, Statham PF. Cauda equina syndrome: what is the correlation between clinical assessment and MRI scanning?. Br J Neurosurg. 2007 Apr. 21(2):201-3. [QxMD MEDLINE Link].
Coscia M, Leipzig T, Cooper D. Acute cauda equina syndrome. Diagnostic advantage of MRI. Spine. 1994 Feb 15. 19(4):475-8. [QxMD MEDLINE Link].
Mailleux R, Redant C, Milbouw G. MR diagnosis of transdural disc herniation causing cauda equine syndrome. JBR-BTR. 2006 Nov-Dec. 89(6):303-5. [QxMD MEDLINE Link].
Kikuchi M, Nagao K, Muraosa Y, Ohnuma S, Hoshino H. Cauda equina syndrome complicating pneumococcal meningitis. Pediatr Neurol. 1999 Feb. 20(2):152-4. [QxMD MEDLINE Link].
Spencer TS, Campellone JV, Maldonado I, et al. Clinical and magnetic resonance imaging manifestations of neurosarcoidosis. Semin Arthritis Rheum. 2005. 34(4):649-661. [QxMD MEDLINE Link].
Podnar S. Electromyography of the anal sphincter: which muscle to examine?. Muscle Nerve. 2003 Sep. 28(3):377-9. [QxMD MEDLINE Link].
Joaquim AF, Powers A, Laufer I, Bilsky MH. An update in the management of spinal metastases. Arq Neuropsiquiatr. 2015 Sep. 73 (9):795-802. [QxMD MEDLINE Link].
Gleave JR, Macfarlane R. Cauda equina syndrome: what is the relationship between timing of surgery and outcome?. Br J Neurosurg. 2002 Aug. 16(4):325-8. [QxMD MEDLINE Link].
Hussain SA, Gullan RW, Chitnavis BP. Cauda equina syndrome: outcome and implications for management. Br J Neurosurg. 2003 Apr. 17(2):164-7. [QxMD MEDLINE Link].
Institute for Clinical Systems Improvement (ICSI). Adult low back pain. Bloomington (MN): Institute for Clinical Systems Improvement (ICSI); 2008 Nov. [Full Text].
Michigan Quality Improvement Consortium. Management of acute low back pain. Southfield (MI): Michigan Quality Improvement Consortium; 2008 Mar. [Full Text].
Bussieres AE, Taylor JA, Peterson C. Diagnostic imaging practice guidelines for musculoskeletal complaints in adults-an evidence-based approach-part 3: spinal disorders. J Manipulative Physiol Ther. 2008 Jan. 31(1):33-88. [QxMD MEDLINE Link]. [Full Text].
Herschorn S, Gajewski J, Ethans K, et al. Efficacy of botulinum toxin A injection for neurogenic detrusor overactivity and urinary incontinence: a randomized, double-blind trial. J Urol. 2011 Jun. 185(6):2229-35. [QxMD MEDLINE Link].
Cruz F, Herschorn S, Aliotta P, et al. Efficacy and safety of onabotulinumtoxinA in patients with urinary incontinence due to neurogenic detrusor overactivity: a randomised, double-blind, placebo-controlled trial. Eur Urol. 2011 Oct. 60(4):742-50. [QxMD MEDLINE Link].
Ginsberg D, et al. Phase 3 Efficacy and Safety Study of OnabotulinumtoxinA in Patients With Urinary Incontinence Due to Neurogenic Detrusor Overactivity. Presented at 107th Annual Meeting of the American Urological Association, Washington, DC. May, 2011.
McCarthy MJ, Aylott CE, Grevitt MP, Hegarty J. Cauda equina syndrome: factors affecting long-term functional and sphincteric outcome. Spine (Phila Pa 1976). 2007 Jan 15. 32(2):207-16. [QxMD MEDLINE Link].
O'Laoire SA, Crockard HA, Thomas DG. Prognosis for sphincter recovery after operation for cauda equina compression owing to lumbar disc prolapse. Br Med J (Clin Res Ed). 1981 Jun 6. 282(6279):1852-4. [QxMD MEDLINE Link]. [Full Text].
Weninger P, Schultz A, Hertz H. Conservative management of thoracolumbar and lumbar spine compression and burst fractures: functional and radiographic outcomes in 136 cases treated by closed reduction and casting. Arch Orthop Trauma Surg. 2009 Feb. 129(2):207-19. [QxMD MEDLINE Link].
Sayegh FE, Kapetanos GA, Symeonides PP, Anogiannakis G, Madentzidis M. Functional outcome after experimental cauda equina compression. J Bone Joint Surg Br. 1997 Jul. 79(4):670-4. [QxMD MEDLINE Link].
Goodman BP. Disorders of the Cauda Equina. Continuum (Minneap Minn). 2018 Apr. 24 (2, Spinal Cord Disorders):584-602. [QxMD MEDLINE Link].

Media Gallery

Muscle groups, surface anatomy, peripheral sensory innervation, and dermatomes of the anterior lower limb. This image should be correlated with Tables 1 and 2 in the text. Image courtesy of Nicholas Y. Lorenzo, MD.
Muscle groups, surface anatomy, peripheral sensory innervation, and dermatomes of the posterior lower limb. This image should be correlated with Tables 1 and 2 in the text. Image courtesy of Nicholas Y. Lorenzo, MD.
Conus/epiconus infarction in the setting of sickle cell crisis. Image courtesy of Matthew J. Baker, MD.
Conus/epiconus infarction in the setting of sickle cell crisis in the same patient shown in the above image. Image courtesy of Matthew J. Baker, MD.
Conus/epiconus infarction in the setting of sickle cell crisis in the same patient shown in the images above. Image courtesy of Matthew J. Baker, MD.
Illustration demonstrating the relevant anatomy of the cauda equina region.
Illustration demonstrating an example of cauda equina syndrome secondary to a spinal neoplasm.
Sagittal MRI of a patient with cauda equina syndrome secondary to a large lumbar disk herniation.
Epidural abscess with effacement of thecal sac in a 56-year-old man.

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Table 1. Symptoms and Signs of Conus Medullaris and Cauda Equina Syndromes

	Conus Medullaris Syndrome	Cauda Equina Syndrome
Presentation	Sudden and bilateral	Gradual and unilateral
Reflexes	Knee jerks preserved but ankle jerks affected	Both ankle and knee jerks affected
Radicular pain	Less severe	More severe
Low back pain	More	Less
Sensory symptoms and signs	Numbness tends to be more localized to perianal area; symmetrical and bilateral; sensory dissociation occurs	Numbness tends to be more localized to saddle area; asymmetrical, may be unilateral; no sensory dissociation; loss of sensation in specific dermatomes in lower extremities with numbness and paresthesia; possible numbness in pubic area, including glans penis or clitoris
Motor strength	Typically symmetric, hyperreflexic distal paresis of lower limbs that is less marked; fasciculations may be present	Asymmetric areflexic paraplegia that is more marked; fasciculations rare; atrophy more common
Impotence	Frequent	Less frequent; erectile dysfunction that includes inability to have erection, inability to maintain erection, lack of sensation in pubic area (including glans penis or clitoris), and inability to ejaculate
Sphincter dysfunction	Urinary retention and atonic anal sphincter cause overflow urinary incontinence and fecal incontinence; tend to present early in course of disease	Urinary retention; tends to present late in course of disease

Table 2. Pain and Deficits Associated with Specific Nerve Roots

Nerve Root	Pain	Sensory Deficit	Motor Deficit	Reflex Deficit
L2	Anterior medial thigh	Upper thigh	Slight quadriceps weakness; hip flexion; thigh adduction	Slightly diminished suprapatellar
L3	Anterior lateral thigh	Lower thigh	Quadriceps weakness; knee extension; thigh adduction	Patellar or suprapatellar
L4	Posterolateral thigh, anterior tibia	Medial leg	Knee and foot extension	Patellar
L5	Dorsum of foot	Dorsum of foot	Dorsiflexion of foot and toes	Hamstrings
S1-2	Lateral foot	Lateral foot	Plantar flexion of foot and toes	Achilles
S3-5	Perineum	Saddle	Sphincters	Bulbocavernosus; anal

Table 3. Root and Peripheral Nerve Innervation of the Lumbosacral Plexus

Muscle	Nerve	Root
Iliopsoas	Femoral	L2, 3, 4
Adductor longus	Obturator	L2, 3, 4
Gracilis	Obturator	L2, 3, 4
Quadriceps femoris	Femoral	L2, 3, 4
Anterior tibial	Deep peroneal	L4, 5
Extensor hallucis longus	Deep peroneal	L4, 5
Extensor digitorum longus	Deep peroneal	L4,5
Extensor digitorum brevis	Deep peroneal	L4, 5, S1
Peroneus longus	Superficial peroneal	L5, S1
Internal hamstrings	Sciatic	L4, 5, S1
External hamstrings	Sciatic	L5, S1
Gluteus medius	Superior gluteal	L4, 5, S1
Gluteus maximus	Inferior gluteal	L5, S1, 2
Posterior tibial	Tibial	L5, S1
Flexor digitorum longus	Tibial	L5, S1
Abductor hallucis brevis	Tibial (medial plantar)	L5, S1, 2
Abductor digiti quinti pedis	Tibial (lateral plantar)	S1, 2
Gastrocnemius lateral	Tibial	L5, S1, 2
Gastrocnemius medial	Tibial	S1, 2
Soleus	Tibial	S1, 2

Table 4. Cauda Equina Versus Conus Medullaris Syndrome

Features	Cauda Equina Syndrome	Conus Medullaris
Vertebral level	L2-sacrum	L1-L2
Spinal level	Injury to the lumbosacral nerve roots	Injury of the sacral cord segment (conus and epiconus) and roots
Severity of symptoms and signs	Usually severe	Usually not severe
Symmetry of symptoms and signs	Usually asymmetric	Usually symmetric
Pain	Prominent, asymmetric, and radicular	Usually bilateral and in the perineal area
Motor	Weakness to flaccid paralysis	Normal motor function to mild or moderate weakness
Sensory	Saddle anesthesia, may be asymmetric	Symmetric saddle distribution, sensory loss of pin prick, and temperature sensations (Tactile sensation is spared.)
Reflexes	Areflexic lower extremities; bulbocavernosus reflex is absent in low CE (sacral) lesions	Areflexic lower extremities (If the epiconus is involved, patellar reflex may be absent, whereas bulbocavernosus reflex may be spared.)
Sphincter and sexual function	Usually late and of lesser magnitude; lower sacral roots involvement can cause bladder, bowel, and sexual dysfunction	Early and severe bowel, bladder, and sexual dysfunction that results in a reflexic bowel and bladder with impaired erection in males
EMG	Multiple root level involvement; sphincters may also be involved	Mostly normal lower extremity with external anal sphincter involvement
Outcome	May be favorable compared with conus medullaris syndrome	The outcome may be less favorable than in patients with CES

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Author

Segun Toyin Dawodu, JD, MD, MS, MBA, LLM, FAAPMR, FAANEM Attending Interventional Physiatrist, Wellspan Health

Segun Toyin Dawodu, JD, MD, MS, MBA, LLM, FAAPMR, FAANEM is a member of the following medical societies: American College of Sports Medicine, American Academy of Physical Medicine and Rehabilitation, Royal College of Surgeons of England, American Association of Neuromuscular and Electrodiagnostic Medicine, American Medical Association, American Medical Informatics Association, Association of Academic Physiatrists, International Society of Physical and Rehabilitation Medicine

Disclosure: Nothing to disclose.

Coauthor(s)

Kirsten A Bechtel, MD Associate Professor of Pediatrics, Section of Pediatric Emergency Medicine, Yale University School of Medicine; Co-Director, Injury Free Coalition for Kids, Yale-New Haven Children's Hospital

Kirsten A Bechtel, MD is a member of the following medical societies: American Academy of Pediatrics

Disclosure: Nothing to disclose.

Michael S Beeson, MD, MBA, FACEP Professor of Emergency Medicine, Northeastern Ohio Universities College of Medicine and Pharmacy; Attending Faculty, Akron General Medical Center

Michael S Beeson, MD, MBA, FACEP is a member of the following medical societies: American College of Emergency Physicians, National Association of EMS Physicians, Council of Residency Directors in Emergency Medicine, Society for Academic Emergency Medicine

Disclosure: Nothing to disclose.

Scott D Hodges, DO Consulting Surgeon, Department of Orthopedic Surgery, Center for Sports Medicine and Orthopedics

Scott D Hodges, DO is a member of the following medical societies: American Academy of Disability Evaluating Physicians, American Medical Association, American Osteopathic Association, American Spinal Injury Association, North American Spine Society, Southern Medical Association, Southern Orthopaedic Association, Tennessee Medical Association

Disclosure: Received royalty from Medtronic for consulting; Received royalty from Biomet Spine for consulting.

S Craig Humphreys, MD Orthopedic Spine Surgeon, Department of Orthopedic Surgery, Center for Sports Medicine and Orthopedics

S Craig Humphreys, MD is a member of the following medical societies: American Spinal Injury Association, Alpha Omega Alpha, American Academy of Orthopaedic Surgeons, American Medical Association, North American Spine Society, Southern Medical Association, Southern Orthopaedic Association, Tennessee Medical Association

Disclosure: Nothing to disclose.

James F Kellam, MD, FRCSC, FACS, FRCS(Ire) Professor, Department of Orthopedic Surgery, University of Texas Medical School at Houston

James F Kellam, MD, FRCSC, FACS, FRCS(Ire) is a member of the following medical societies: American Academy of Orthopaedic Surgeons, Orthopaedic Trauma Association, Royal College of Physicians and Surgeons of Canada

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.

Chief Editor

Nicholas Lorenzo, MD, CPE, MHCM, FAAPL Co-Founder and Former Chief Publishing Officer, eMedicine and eMedicine Health, Founding Editor-in-Chief, eMedicine Neurology; Founder and Former Chairman and CEO, Pearlsreview; Founder and CEO/CMO, PHLT Consultants; Former Chief Medical Officer, MeMD Inc

Nicholas Lorenzo, MD, CPE, MHCM, FAAPL is a member of the following medical societies: Alpha Omega Alpha, American Academy of Neurology, American Association for Physician Leadership

Disclosure: Nothing to disclose.

Additional Contributors

J Stephen Huff, MD, FACEP Professor of Emergency Medicine and Neurology, Department of Emergency Medicine, University of Virginia School of Medicine

J Stephen Huff, MD, FACEP is a member of the following medical societies: American Academy of Neurology, American College of Emergency Physicians, Society for Academic Emergency Medicine

Disclosure: Nothing to disclose.

Milind J Kothari, DO Associate Dean, Collegia Program, University of South Florida Morsani College of Medicine

Milind J Kothari, DO is a member of the following medical societies: American Academy of Neurology, American Association of Neuromuscular and Electrodiagnostic Medicine, American Neurological Association

Disclosure: Nothing to disclose.

Acknowledgements

The authors and editors of Medscape Reference gratefully acknowledge the contributions of previous author Jason C Eck, DO, MS,to the development and writing of a source article.