Online Module: Online Module: Cauda Equina Cauda Equina

SyndromeSyndromeLSUHSC NeuroscienceLSUHSC Neuroscience

Student ClerkshipStudent Clerkship

Major goals/objectivesMajor goals/objectives

Discuss the signs/symptoms of CES.Discuss the signs/symptoms of CES. Outline the role of surgery in dealing Outline the role of surgery in dealing

with CES.with CES. Review the prognosis for return of Review the prognosis for return of

function in patients with CES.function in patients with CES.

Minor goals/objectivesMinor goals/objectives

Briefly review/list various “less-Briefly review/list various “less-common” causes of CES.common” causes of CES.

Briefly discuss some of the Briefly discuss some of the pathophysiology behind the pathophysiology behind the syndrome.syndrome.

The Cauda EquinaThe Cauda Equina

The Cauda Equina (i.e., “horse’s The Cauda Equina (i.e., “horse’s tail”) is the name given the group of tail”) is the name given the group of nerve roots that arise from the nerve roots that arise from the culmination of the spinal cord (the culmination of the spinal cord (the conus medullaris) and extend conus medullaris) and extend inferiorly in the intradural space inferiorly in the intradural space towards the coccyx.towards the coccyx.

The Cauda EquinaThe Cauda Equina

The “Cauda Equina” was so-named by French The “Cauda Equina” was so-named by French anatomist Andreas Lazarius in the 1600’s.anatomist Andreas Lazarius in the 1600’s.

Generally considered to be comprised of nine Generally considered to be comprised of nine pairs of nerve roots, starting with L2 and pairs of nerve roots, starting with L2 and extending to and including S5 (ok, and the extending to and including S5 (ok, and the coccyx root as well).coccyx root as well).

Provides motor innervation to the hips, knees, Provides motor innervation to the hips, knees, ankles, and feet…as well as sphincter ankles, and feet…as well as sphincter innervation, sensory innervation to the innervation, sensory innervation to the “saddle region,” and parasympathetic “saddle region,” and parasympathetic innervation to the bladder (and distal bowel). innervation to the bladder (and distal bowel).

Cauda Equina Syndrome Cauda Equina Syndrome (CES)(CES)

Caused by Caused by compression or injury compression or injury to the nerve roots to the nerve roots which descend from which descend from the conus medullaris.the conus medullaris.

Many different Many different possible causes.possible causes.

Underlying chronic Underlying chronic conditions can conditions can predisposepredispose to CES, as to CES, as well as cause it in well as cause it in some cases.some cases.

CESCES

Cauda EquinaCauda Equina Syndrome Syndrome was first was first described by Mixter and Barr in described by Mixter and Barr in 1934.1934.

A A variablevariable presentation consisting of presentation consisting of a constellation of symptoms which a constellation of symptoms which includes lower back pain, includes lower back pain, asymmetrical LE paralysis, variable asymmetrical LE paralysis, variable sensory deficits, and loss of bowel sensory deficits, and loss of bowel and bladder control. and bladder control.

CESCES Major point to keep in mind is this: Major point to keep in mind is this:

Cauda Equina Syndrome has a variable Cauda Equina Syndrome has a variable presentation and is widely thought to be presentation and is widely thought to be regularly misdiagnosed or just plain regularly misdiagnosed or just plain missed. missed.

Failure to recognize the syndrome Failure to recognize the syndrome (especially in the emergency setting) is (especially in the emergency setting) is an ongoing issue and the subject of an ongoing issue and the subject of continued litigation in patients who were continued litigation in patients who were eventually recognized to have this, but in eventually recognized to have this, but in whom deficits remain after surgery.whom deficits remain after surgery.

CES signs/symptomsCES signs/symptoms

The most common symptom in The most common symptom in patients presenting with CES is patients presenting with CES is Low Back Pain (LBP).Low Back Pain (LBP). >90% of patients>90% of patients

Nonspecific, yes, but index of Nonspecific, yes, but index of suspicion should be high and suspicion should be high and appropriate history should be appropriate history should be elicited, especially if coexisting elicited, especially if coexisting symptoms/complaints are present.symptoms/complaints are present.

CES signs/symptomsCES signs/symptoms

The most consistent sign in cauda The most consistent sign in cauda equina syndrome is urinary retention equina syndrome is urinary retention (incidence approaches 90%).(incidence approaches 90%). Check post-void residual – normal is between Check post-void residual – normal is between

50 and 100 mL and >200 is positive for 50 and 100 mL and >200 is positive for retention.retention.

Overflow incontinence can be seen as the Overflow incontinence can be seen as the bladder fills.bladder fills.

Anal sphincter tone is diminished in 50-Anal sphincter tone is diminished in 50-75% of patients with CES.75% of patients with CES. Fecal incontinence can be seen.Fecal incontinence can be seen.

CES signs/symptomsCES signs/symptoms ““Saddle Saddle

anesthesia” is the anesthesia” is the most commonly most commonly observed sensory observed sensory deficit in patients deficit in patients with CES.with CES. Roughly 75% of pts.Roughly 75% of pts.

Sensory loss seen Sensory loss seen around the anus, around the anus, lower genitalia, lower genitalia, perineum, buttocks, perineum, buttocks, sometimes even the sometimes even the posterior thighs.posterior thighs. ██████

CES signs/symptomsCES signs/symptoms

LBP is a nonspecific finding.LBP is a nonspecific finding. New New LBP is rarely seen in cases of LBP is rarely seen in cases of

CES without other symptoms being CES without other symptoms being present.present.

Sciatica, when present, is usually Sciatica, when present, is usually bilateral (but can be unilateral).bilateral (but can be unilateral).

CES signs/symptomsCES signs/symptoms

Motor weakness – can be severe, and usually Motor weakness – can be severe, and usually involves involves more more than a single nerve root.than a single nerve root.

May be bilateral, but is rarely symmetric May be bilateral, but is rarely symmetric (one side is usually weaker/stronger than the (one side is usually weaker/stronger than the other).other).

Untreated motor weakness can become Untreated motor weakness can become permanent disability, and can progress to permanent disability, and can progress to complete paralysis/paraplegia.complete paralysis/paraplegia.

Reflexes are HYPO-active; no long tract Reflexes are HYPO-active; no long tract signs!signs!

Onset of CESOnset of CES

Acute presentation is most common, and Acute presentation is most common, and is most commonly seen in patients with a is most commonly seen in patients with a prior history of LBP.prior history of LBP.

Acute presentation in patients with no Acute presentation in patients with no prior history of LBP and/or sciatica prior history of LBP and/or sciatica occasionallyoccasionally seen. seen.

Insidious onset and progression of Insidious onset and progression of symptoms is rare, but is associated with symptoms is rare, but is associated with better chance of return of function better chance of return of function ((especiallyespecially bladder function). bladder function).

Incidence of CESIncidence of CES Incidence of CES in U.S. is estimated Incidence of CES in U.S. is estimated

between 2 and 4 cases per 10,000 between 2 and 4 cases per 10,000 patients with chief complaint which patients with chief complaint which includes LBP.includes LBP.

Estimated to be present to some degree Estimated to be present to some degree in as many as 2% of patients undergoing in as many as 2% of patients undergoing surgery for HNP.surgery for HNP.

High clinical suspicion must be kept in High clinical suspicion must be kept in patients presenting with LBP and other patients presenting with LBP and other symptoms. Good history and physical symptoms. Good history and physical exam-taking is key!exam-taking is key!

Possible etiology of Possible etiology of injury in CESinjury in CES

Herniated lumbar discHerniated lumbar disc TumorTumor TraumaTrauma Spinal epidural hematomaSpinal epidural hematoma InfectionInfection OtherOther Basic idea: Severe Canal Stenosis Basic idea: Severe Canal Stenosis

(narrowing)(narrowing)

Pathophysiology of CESPathophysiology of CES

Nerve roots of the Cauda Equina are Nerve roots of the Cauda Equina are susceptible to injury from compression susceptible to injury from compression partly due to a poorly developed epineurium partly due to a poorly developed epineurium (less protection from “outside stresses” or (less protection from “outside stresses” or tension).tension).

Proximal nerve roots are relatively Proximal nerve roots are relatively hypovascularized and are supplemented by hypovascularized and are supplemented by increased vascular increased vascular permeabilitypermeability in this area in this area as well as diffusion from surrounding CSF as well as diffusion from surrounding CSF (which is thought to contribute to swelling (which is thought to contribute to swelling and edema in irritated nerve roots).and edema in irritated nerve roots).

Pathophysiology of CESPathophysiology of CES

Unmyelinated, smaller Unmyelinated, smaller parasympathetic/pain fibers are parasympathetic/pain fibers are more susceptible to compression and more susceptible to compression and injury from compressive forces.injury from compressive forces.

Herniated Lumbar Disc Herniated Lumbar Disc in CESin CES

Herniation of a Herniation of a [typically] massive [typically] massive portion of portion of intervertebral disc intervertebral disc material into the material into the spinal canal causing spinal canal causing compression of the compression of the descending nerves of descending nerves of the cauda equina.the cauda equina.

Represents between Represents between 15 and 20% of CES 15 and 20% of CES cases.cases.

Herniated Lumbar Disc Herniated Lumbar Disc in CESin CES

Ten cases reported in the literature of CES Ten cases reported in the literature of CES being caused by very large disc fragment[s] being caused by very large disc fragment[s] which have migrated into the posterior which have migrated into the posterior epidural space causing posterior epidural space causing posterior compression.compression.

More than 100 cases of reports of intradural More than 100 cases of reports of intradural migration of herniated disc fragments.migration of herniated disc fragments.

Some estimates place prevalence of CES as Some estimates place prevalence of CES as high as 2% of herniated intervertebral high as 2% of herniated intervertebral discs!discs!

Herniated Lumbar Disc Herniated Lumbar Disc in CESin CES

Variability in presentation is a direct Variability in presentation is a direct result of level of involvement.result of level of involvement.

Most common level of involvement is Most common level of involvement is L4-5 (57%), followed by L5-S1 L4-5 (57%), followed by L5-S1 (30%), then L3-4 (13%).(30%), then L3-4 (13%).

Most common presentation of CES Most common presentation of CES secondary to acute disc herniation is secondary to acute disc herniation is males age 30-40 with prior history of males age 30-40 with prior history of LBP. Most have NOT been operated LBP. Most have NOT been operated on previously.on previously.

Primary Tumor in CESPrimary Tumor in CES

Ependymomas account for roughly Ependymomas account for roughly 90% of primary tumors of the filum 90% of primary tumors of the filum terminale and cauda equina, the terminale and cauda equina, the majority of which (~60%) are of the majority of which (~60%) are of the myxopapillary subtype. Still, CES myxopapillary subtype. Still, CES from this is rare.from this is rare.

Schwannomas in the area of the Schwannomas in the area of the conus or cauda equina can also conus or cauda equina can also occur and cause CES, but are rare.occur and cause CES, but are rare.

Other lesions causing Other lesions causing CESCES

Tarlov cysts, while rarely symptomatic, Tarlov cysts, while rarely symptomatic, have been described in the literature as have been described in the literature as causing CES.causing CES.

Primary sacral neoplasms, such as Primary sacral neoplasms, such as chordoma or a destructive bony lesion, chordoma or a destructive bony lesion, can cause CES through collapse of bone can cause CES through collapse of bone and structure.and structure.

Again, in all cases, the mechanism is Again, in all cases, the mechanism is compression of the nerve rootscompression of the nerve roots. Anything . Anything that does this can cause CES.that does this can cause CES.

Metastatic Tumor in CESMetastatic Tumor in CES

Incidence of spinal metastasis is Incidence of spinal metastasis is increasing due to improvements in increasing due to improvements in diagnostic modalities, imaging, and diagnostic modalities, imaging, and treatment regimens.treatment regimens.

The most common non-CNS metastatic The most common non-CNS metastatic tumor causing spinal metastases is tumor causing spinal metastases is lung; however CES occurs in less lung; however CES occurs in less than 1% of cases involving spinal than 1% of cases involving spinal spread of metastatic lung cancer.spread of metastatic lung cancer.

Metastatic tumor and Metastatic tumor and CESCES

Drop metastases from inctracranial Drop metastases from inctracranial ependymomas, germinomas, and ependymomas, germinomas, and other primary intraneural tumors other primary intraneural tumors can cause CES from seeding via the can cause CES from seeding via the CSF space.CSF space.

Primary genitourinary and Primary genitourinary and gynecologic tumor extension into the gynecologic tumor extension into the cauda equina region has been cauda equina region has been described.described.

Trauma in CESTrauma in CES

Mechanical disruption of the spine Mechanical disruption of the spine from subluxation, sponylolisthesis, from subluxation, sponylolisthesis, and/or compression of the neural and/or compression of the neural elements from hematoma, etc., can elements from hematoma, etc., can cause CES.cause CES.

True incidence in the trauma setting True incidence in the trauma setting is somewhat unclear due to is somewhat unclear due to coexisting injuries.coexisting injuries.

Other causes of CESOther causes of CES

Spinal Epidural HematomaSpinal Epidural Hematoma InfectionInfection Again…Again…AnythingAnything that leads to that leads to

compression of the roots.compression of the roots.

Surgical Issues with CESSurgical Issues with CES

The major point of contention with The major point of contention with Cauda Equina surgical intervention Cauda Equina surgical intervention revolves around timing – when is it revolves around timing – when is it most appropriate to operate on most appropriate to operate on these lesions? IS THIS AN these lesions? IS THIS AN EMERGENCY???EMERGENCY???

PrognosisPrognosis

Shapiro et al noted that patients who Shapiro et al noted that patients who underwent surgery within 48 hrs of symptom underwent surgery within 48 hrs of symptom onset, 95% recovered continence and normal onset, 95% recovered continence and normal function within six months. Conversely, 63% function within six months. Conversely, 63% of those patients whose surgery was delayed of those patients whose surgery was delayed beyond 48 hrs still required catheterization beyond 48 hrs still required catheterization after 6 months.after 6 months.

Generally, patients show improvement first in Generally, patients show improvement first in pain, then with motor function – while pain, then with motor function – while autonomic signs are last to improve (and the autonomic signs are last to improve (and the least likely).least likely).

When to operateWhen to operate A meta-analysis that came out of Johns Hopkins A meta-analysis that came out of Johns Hopkins

University in 2000 (total 332 patients) that University in 2000 (total 332 patients) that looked at patients with CES secondary to looked at patients with CES secondary to lumbar disc herniations, Ahn et al determined a lumbar disc herniations, Ahn et al determined a significant improvement in outcome for patients significant improvement in outcome for patients operated on within 48 hours of onset of operated on within 48 hours of onset of symptoms when compared with those operated symptoms when compared with those operated on more than 48 hours after onset of symptoms.on more than 48 hours after onset of symptoms.

Within those respective groups, there was no Within those respective groups, there was no significant difference in outcomes for earlier or significant difference in outcomes for earlier or later times.later times.

When to operateWhen to operate

There is still debate about this in the There is still debate about this in the literature. In 2004, Radulovic et al literature. In 2004, Radulovic et al published a retrospective analysis of published a retrospective analysis of their own series of patients (47) where their own series of patients (47) where they found no significant difference in they found no significant difference in outcome regardless of time to outcome regardless of time to operation. This study, however, did operation. This study, however, did not focus on onset of symptoms; but not focus on onset of symptoms; but rather, time from presentation.rather, time from presentation.

Time to surgery - Time to surgery - OutcomeOutcome

More recently, McCarthy et al More recently, McCarthy et al published their series of 42 patients published their series of 42 patients with CES secondary to disc with CES secondary to disc herniation and found no significant herniation and found no significant improvement in patients’ outcome improvement in patients’ outcome regardless of time to surgery after regardless of time to surgery after onset of symptoms.onset of symptoms.

Current Current recommendationsrecommendations

Current recommendations outline a Current recommendations outline a goal of performing surgery within 24 goal of performing surgery within 24 hours of presentation if at all hours of presentation if at all possible. possible.

A major line of thinking behind this A major line of thinking behind this plan lies in the medical-legal pitfalls plan lies in the medical-legal pitfalls of dealing with CES and the residual of dealing with CES and the residual deficits dealt with by the patients.deficits dealt with by the patients.

Operating for CESOperating for CES

The goal of the operation is to The goal of the operation is to decompress the nerve roots of the decompress the nerve roots of the cauda equina.cauda equina.

Instrumentation is rarely used for Instrumentation is rarely used for acute disc herniations, but is more acute disc herniations, but is more commonly used in cases of CES caused commonly used in cases of CES caused by trauma or severe degenerative by trauma or severe degenerative disease of the spine from which CES disease of the spine from which CES has been the result of instability.has been the result of instability.

SummarySummary