Diagnostic Considerations
Conus medullaris infarction should be considered in the differential diagnosis, and a source of emboli should be sought by ultrasound to rule out an abdominal aortic aneurysm. Heterotopic ossification should be ruled out by triple-bone scan in a patient with pain and swelling of the lower extremity in whom deep venous thrombosis (DVT) has been ruled out. In other words, heterotopic ossification should always be considered as a differential diagnosis of DVT in these patients.
Metastatic malignant neoplasms of the spine should be ruled out and the primary source sought as part of the workup in any patient presenting with any of the symptoms listed in Clinical.
Other problems to be considered include the following: [78]
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Amyloidosis with deposits in the spinal cord
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Ankylosing spondylitis and other spondyloarthropathy
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Charcot-Marie-Tooth disease (types 1 and 3)
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Intravascular lymphomatosis
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Lipomas within the spine
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Lumbar stenosis (multilevel)
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Paget disease of the spine
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Spinal infection/abscess and meningitis
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Tethered cord syndrome/short filum terminale
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Vascular intermittent claudication
Differential Diagnoses
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Amyotrophic Lateral Sclerosis in Physical Medicine and Rehabilitation
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Diabetic Neuropathy
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Guillain-Barré Syndrome
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Neoplasms, Spinal Cord
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Spinal Cord Infections
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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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Conus/epiconus infarction in the setting of sickle cell crisis. Image courtesy of Matthew J. Baker, MD.
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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.
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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.
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Illustration demonstrating the relevant anatomy of the cauda equina region.
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Illustration demonstrating an example of cauda equina syndrome secondary to a spinal neoplasm.
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Sagittal MRI of a patient with cauda equina syndrome secondary to a large lumbar disk herniation.
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Epidural abscess with effacement of thecal sac in a 56-year-old man.
Tables
|
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 |
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 |
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 |
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 |
