Cauda Equina Syndrome

Patients initially present with lower back pain in almost all cases, usually with sciatica and pain in the genitalia and rectum [10]. Impaired sphincter function occurs in 15-30% of patients [10].

The clinical picture of cauda equina syndrome includes [2] [13]:

• Lower back pain 
• Neurological deficits (distal motor weakness, sensory disturbance in the legs, numbness and pain, absent lower-limb reflexes)
• Urological symptoms (bladder and bowel incompetence, impotence may occur with erectile dysfunction due to the lack of sensation in pubic area [14])
• Scoliosis and foot deformities. 

Diagnosis and treatment are often delayed because the symptoms are not recognized immediately [6]. Cauda equina syndrome may present as acute, sub-acute or insidious [1] [4] [15]. The precipitating factor in the acute form may be traumatic injury or movements as simple as stooping, with or without heavy lifting [15].

Urinary manifestations include the following [4] [7]:

• Retention
• Difficulty initiating micturition
• Decreased urethral sensation

Bowel disturbances may include the following [7]:

• Incontinence
• Constipation
• Loss of anal tone and sensation

Complications include [4]:

• Thromboembolic phenomena
• Neurogenic bladder/bowel
• Erectile dysfunction
• Pressure ulcers
• Osteoporosis
• Chronic neuropathic pain
• Spasticity/contractures
• Recurrent urinary tract infections
• Bladder calculi

The diagnosis of cauda equina syndrome is usually made by history and physical findings [7]. Patients who present with bowel or bladder disturbances, leg weakness, or rectal and genital sensory deficits should be evaluated [7] [16]. Radiologic and laboratory studies help to confirm the diagnosis and identify the pathology and underlying cause [1] [13]. Magnetic resonance imaging is the most effective means of definitive diagnosis [7] [13]. Urgent magnetic resonance imaging should be obtained in all patients with lumbar back pain and new onset urinary symptoms [7] [17]. However, magnetic resonance imaging may be normal in as many as 43% of patients with suspected cauda equina syndrome [7]. Magnetic resonance imaging with gadolinium contrast has improved results [7]. 

Other examinations include [4] [7]:

• Myelography
• Computed tomography 
• Bone scans can detect malignant tumors and inflammation of the vertebrae

Laboratory studies may include [1] [3]:

• Basic blood tests, chemistries, fasting blood sugar
• Erythrocyte sedimentation rate
• Renal function
• Syphilis and Lyme serology
• Cerebrospinal fluid examination

Other procedures

• Needle electromyography can show acute denervation and predict outcome and monitor recovery [1] [7]. 
• Somatosensory evoked potentials can be used to rule out multiple sclerosis [1]. 
• Inflammatory or infective diseases of the meninges or spinal cord are ruled out using lumbar puncture [1] [14].

No proven medical treatment exists for the treatment of cauda equina syndrome. Therapy needs to be individualized and directed toward the underlying cause of the syndrome [11]. Since compression of the lower spinal column is the primary cause of cauda equina syndrome, surgical decompression is the primary treatment for the condition [17]. The major factors effecting operative outcome include [10] [17]:

• The severity of the sphincter dysfunction
• The extent of sensory loss
• Early diagnosis and surgical intervention

Early diagnosis, evaluation by a neurosurgeon, and surgical decompression should be instituted before the neurological damage becomes permanent [4] [10]. The onset of bladder paralysis is the most important indication for immediate surgery [3]. Laminectomy and discectomy are the recommended treatment and should be an emergency intervention [8] [17]. Posterior decompression and stabilization offers the best neurological outcomes [11]. Surgery is recommended within 48 hours, but newer studies failed to see a correlation between the timing of surgery and the outcomes [3] [8] [15] [17].

Medications

Treatment with pharmaceuticals may include [11]:

• Antibiotics to treat cauda equina syndrome due to infections
• Antiinflammatories, steroids and non-steroidal anti-inflammatory drugs (NSAIDs) to reduce or prevent swelling
• Chemotherapy for the treatment of neoplastic tumors

Other therapy

Rehabilitation post-surgery should include physical and occupational therapy. The goal is a return to independent activities of daily living and the maintenance of and improvement of strength and endurance [9] [10]. Prevention and treatment of possible complications, especially deep venous thrombosis, bladder and bowel problems, and decubitus ulcers, should also be part of any treatment plan.

Patients who have had cauda equina syndrome often do not return to a normal status [12]. Prognosis for recovery is improved when the cause of the disorder is identified early and appropriate treatment instituted [9]. Residual weakness, incontinence, impotence, and/or sensory abnormalities are potential problems if therapy is delayed [1] [6].

Patients with bladder incontinence or retention regain continence post-surgery in over 90% of cases [5] [8]. Outcomes postoperatively are worse in patients with bowel dysfunction [5] [10]. Morbidity and mortality rates depend on the underlying etiology [1] [8]. Increased age is also associated with poorer postoperative outcomes [6].

Cauda equina syndrome is caused by a narrowing of the spinal canal that results in compression of the nerve roots below the spinal cord, the cauda equina [3]. The cauda equina provides sensory innervation to the saddle area, motor innervation to the urinary and anal sphincters, parasympathetic innervation to the bladder and lower bowel, and sensation and motor control to the lower extremities [3] [5].

The most common causes of caudal equina syndrome include acute disc herniation or traumatic injury at the terminal portion of the spinal cord [2] [7], tumors (malign or benign), or infection [7]. Herniated lower lumbar or sacral discs are the most common cause [1] [4] [7]. Cauda equina syndrome is an emergency [1] requiring immediate diagnosis (usually with magnetic resonance imaging) and surgical intervention [5]. The onset of symptoms in cauda equina syndrome may be acute or may have a gradual onset [7]. The gradual onset has a better prognosis. The outcome of the disorder depends on how quickly it is diagnosed and treated [8].

Individuals with congenital developmental abnormalities or degenerative conditions, such as ankylosing spondylitis, spondylosis, and spondylolisthesis, are more likely to develop cauda equina syndrome, because narrowing already exists [9].  Complications of the condition may include bowel and bladder dysfunction, lower extremity sensory loss, and lower extremity paralysis [1] [10].

Common causes of cauda equina syndrome include [3] [2] [8] [11]:

• Disc herniation
• Intradural disc rupture
• Spinal stenosis
• Traumatic injury, fracture or subluxation
• Primary and metastatic tumors
• Infections
• Hemorrhage or emboli
• Iatrogenic injury resulting from complications of spinal surgery or spinal anesthesia

Other, rare causes include the following [3] [8]:

• Spinal hemorrhage
• Congenital anomalies of the spine
• Multiple sclerosis
• Spinal arteriovenous malformations
• Late-stage ankylosing spondylitis
• Neurosarcoidosis
• Deep venous thrombosis of the spinal veins

Cauda equina syndrome is rare [4] [7]. The incidence is variable and depends on the etiology of the syndrome [7]. Mean age at onset of cauda equina syndrome is 41 years of age (24-67 years) but it can occur at any age [12]. Cauda equina syndrome due to traumatic injury is not age specific. Non-traumatic forms of cauda equina Syndrome occur primarily in adults [12]. Cauda equina syndrome, secondary to disk herniation, is most common in men 40 -to50 years of age [6]. The incidence is not affected by gender or race. Males and females are equally affected [7] [12].

Cauda equina syndrome results from injury to the lumbosacral nerve roots at the end of the spinal cord below the tip of the conus medullaris [1]. The spinal cord connects the peripheral and spinal nerves to the brain. The cauda equina provides the connection of the spinal cord to the lower peripheral nervous system [1]. It is a purely lower motor neuron injury [11].

Compression of the nerve fibers results in increased vascular permeability and subsequent diffusion of cerebral spinal fluid. This causes edema which accentuates the mechanical compression [1] [11]. The symptoms are due to compression, displacement, entrapment, or trauma to the cauda equina [9]. The level of spinal injury and the initial cause of compression affect the symptomatology and outcome [11]. Symptoms depend on which roots of the cauda equina are involved [9].

Tethered spinal cord is a cause of cauda equina syndrome seen more in children, but also occurs in adults [13]. This is due to a congenital abnormality, a tight, thickened, shortened filum terminale, intradural scar formation, or other lesion, that leads to fixation of the lower spinal cord [11] [13]. Movement of the spinal cord is impaired and leads to chronic local ischemia, swelling, and compression [1] [13].

Compression of the cauda equina can result in decreased sensation to the saddle area, paralysis of bowel and bladder sensation and function, sensory loss and motor dysfunction of the lower extremities [1] [10] [13].

Differential diagnoses include [9] [11] [13]:

• Amyotrophic lateral sclerosis
• Diabetic neuropathy
• Guillain-Barré Syndrome
• HIV-1 associated neuromuscular complications
• Multiple sclerosis
• Neoplasms of spinal cord
• Neurosarcoidosis
• Spinal cord infections
• Traumatic peripheral nerve lesions

Prevention of lower spinal injury is the only way to prevent the syndrome. Prevention of cauda equina syndrome depends upon the early identification of lower spine defects that may result in compression of the nerve roots. Immediate intervention to relieve the compression improves the progression and the occurrence of complications [10].

Cauda equina syndrome is a rare disorder characterized by a group of symptoms resulting from compression of the nerve roots of the cauda equina [1] [2]. The cauda equina, Latin for ‘horse's tail’, is a collection of nerve roots located at the end of the spinal cord at the first and second lumbar vertebrae [1] [3]. The symptoms of the disorder are due to damage to nerve fibers due to compression and ischemia. Onset may be sudden or gradual. Symptoms include low back pain, sciatica, saddle sensory loss, bladder and bowel dysfunction, and lower extremity motor dysfunction [1] [3] [4]. Damage may be irreversible [1].

Cauda equina syndrome is considered a surgical emergency [1] and surgical intervention to relieve nerve compression is the most effective treatment [1] [5]. The causes of the condition are varied, but the most common causes are a displaced herniated disc or traumatic injury to the lumbar or sacral vertebrae [3] [5] [6].

What is cauda equina syndrome?

Cauda equina syndrome is a rare group of symptoms resulting from compression of the nerve roots located at the end of the spinal cord at the level of the first and second lumbar vertebrae. It results from injury to the spinal cord or vertebrae due to a herniated disk or trauma.

What are the symptoms of cauda equina syndrome?

Symptoms include low back pain, sciatica, saddle sensory loss, bladder and bowel dysfunction, and lower extremity motor disability. Onset may be sudden or gradual. Damage may be irreversible.

What causes cauda equina syndrome?

The symptoms of cauda equina are caused by damage to nerve fibers from compression of the nerve roots. Causes of cauda equina syndrome include:

• Disc herniation
• Spinal stenosis 
• Traumatic injury, fracture or subluxation
• Primary and metastatic tumors 
• Infections 
• Hemorrhage or emboli
• Congenital anomalies of the spine
• Iatrogenic injury resulting from complications of spinal surgery or spinal anesthesia

Herniated disk is most common cause. Cauda equina syndrome due to traumatic injury is not age specific. Non-traumatic forms occur primarily in adults.

Who gets cauda equina syndrome?

Cauda equina syndrome is rare. Mean age at onset is 41 years of age (24-67 years) but can occur at any age. The incidence of cauda equina syndrome is not affected by gender or race. Males and females are equally affected.

How is it diagnosed?

Cauda equina syndrome is diagnosed by its presentation, group of symptoms, history of onset and/or injury. Definitive diagnosis is made by magnetic resonance imaging.

How is cauda equina syndrome treated?

The only effective treatment of cauda equina is surgery to decompress the affected nerve fibers. It is considered a surgical emergency and the sooner the surgery is performed the better the prognosis for recovery.

What are the complications?

Complications of cauda e equina include:

• Bladder/bowel dysfunction and incontinence
• Erectile dysfunction
• Pressure ulcers
• Osteoporosis
• Chronic pain
• Spasticity/contractures
• Recurrent urinary tract infections
• Bladder calculi

How can it be prevented?

Prevention of lower spinal injury is the only way to prevent the syndrome. Prevention of complications depends upon the early identification of the syndrome and immediate surgery to relieve the compression.

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