1. Online Module: Cauda Equina Syndrome LSUHSC Neuroscience Student Clerkship

2. Major goals/objectives Discuss the signs/symptoms of CES. Discuss the signs/symptoms of CES. Outline the role of surgery in dealing with CES. Outline the role of surgery in dealing with CES. Review the prognosis for return of function in patients with CES. Review the prognosis for return of function in patients with CES.

3. Minor goals/objectives Briefly review/list various “less-common” causes of CES. Briefly review/list various “less-common” causes of CES. Briefly discuss some of the pathophysiology behind the syndrome. Briefly discuss some of the pathophysiology behind the syndrome.

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

5. The Cauda Equina The “Cauda Equina” was so-named by French anatomist Andreas Lazarius in the 1600’s. The “Cauda Equina” was so-named by French anatomist Andreas Lazarius in the 1600’s. Generally considered to be comprised of nine pairs of nerve roots, starting with L2 and extending to and including S5 (ok, and the coccyx root as well). Generally considered to be comprised of nine pairs of nerve roots, starting with L2 and extending to and including S5 (ok, and the coccyx root as well). Provides motor innervation to the hips, knees, ankles, and feet…as well as sphincter innervation, sensory innervation to the “saddle region,” and parasympathetic innervation to the bladder (and distal bowel). Provides motor innervation to the hips, knees, ankles, and feet…as well as sphincter innervation, sensory innervation to the “saddle region,” and parasympathetic innervation to the bladder (and distal bowel).

6. Cauda Equina Syndrome (CES) Caused by compression or injury to the nerve roots which descend from the conus medullaris. Caused by compression or injury to the nerve roots which descend from the conus medullaris. Many different possible causes. Many different possible causes. Underlying chronic conditions can predispose to CES, as well as cause it in some cases. Underlying chronic conditions can predispose to CES, as well as cause it in some cases.

7. CES Cauda Equina Syndrome was first described by Mixter and Barr in 1934. Cauda Equina Syndrome was first described by Mixter and Barr in 1934. A variable presentation consisting of a constellation of symptoms which includes lower back pain, asymmetrical LE paralysis, variable sensory deficits, and loss of bowel and bladder control. A variable presentation consisting of a constellation of symptoms which includes lower back pain, asymmetrical LE paralysis, variable sensory deficits, and loss of bowel and bladder control.

8. CES Major point to keep in mind is this: Cauda Equina Syndrome has a variable presentation and is widely thought to be regularly misdiagnosed or just plain missed. Major point to keep in mind is this: Cauda Equina Syndrome has a variable presentation and is widely thought to be regularly misdiagnosed or just plain missed. Failure to recognize the syndrome (especially in the emergency setting) is an ongoing issue and the subject of continued litigation in patients who were eventually recognized to have this, but in whom deficits remain after surgery. Failure to recognize the syndrome (especially in the emergency setting) is an ongoing issue and the subject of continued litigation in patients who were eventually recognized to have this, but in whom deficits remain after surgery.

9. CES signs/symptoms The most common symptom in patients presenting with CES is Low Back Pain (LBP). The most common symptom in patients presenting with CES is Low Back Pain (LBP). >90% of patients >90% of patients Nonspecific, yes, but index of suspicion should be high and appropriate history should be elicited, especially if coexisting symptoms/complaints are present. Nonspecific, yes, but index of suspicion should be high and appropriate history should be elicited, especially if coexisting symptoms/complaints are present.

10. CES signs/symptoms The most consistent sign in cauda equina syndrome is urinary retention (incidence approaches 90%). The most consistent sign in cauda equina syndrome is urinary retention (incidence approaches 90%). Check post-void residual – normal is between 50 and 100 mL and >200 is positive for retention. Check post-void residual – normal is between 50 and 100 mL and >200 is positive for retention. Overflow incontinence can be seen as the bladder fills. Overflow incontinence can be seen as the bladder fills. Anal sphincter tone is diminished in 50-75% of patients with CES. Anal sphincter tone is diminished in 50-75% of patients with CES. Fecal incontinence can be seen. Fecal incontinence can be seen.

11. CES signs/symptoms “Saddle anesthesia” is the most commonly observed sensory deficit in patients with CES. “Saddle anesthesia” is the most commonly observed sensory deficit in patients with CES. Roughly 75% of pts. Roughly 75% of pts. Sensory loss seen around the anus, lower genitalia, perineum, buttocks, sometimes even the posterior thighs. Sensory loss seen around the anus, lower genitalia, perineum, buttocks, sometimes even the posterior thighs. ██████

12. CES signs/symptoms LBP is a nonspecific finding. LBP is a nonspecific finding. New LBP is rarely seen in cases of CES without other symptoms being present. New LBP is rarely seen in cases of CES without other symptoms being present. Sciatica, when present, is usually bilateral (but can be unilateral). Sciatica, when present, is usually bilateral (but can be unilateral).

13. CES signs/symptoms Motor weakness – can be severe, and usually involves more than a single nerve root. Motor weakness – can be severe, and usually involves more than a single nerve root. May be bilateral, but is rarely symmetric (one side is usually weaker/stronger than the other). May be bilateral, but is rarely symmetric (one side is usually weaker/stronger than the other). Untreated motor weakness can become permanent disability, and can progress to complete paralysis/paraplegia. Untreated motor weakness can become permanent disability, and can progress to complete paralysis/paraplegia. Reflexes are HYPO-active; no long tract signs! Reflexes are HYPO-active; no long tract signs!

14. Onset of CES Acute presentation is most common, and is most commonly seen in patients with a prior history of LBP. Acute presentation is most common, and is most commonly seen in patients with a prior history of LBP. Acute presentation in patients with no prior history of LBP and/or sciatica occasionally seen. Acute presentation in patients with no prior history of LBP and/or sciatica occasionally seen. Insidious onset and progression of symptoms is rare, but is associated with better chance of return of function (especially bladder function). Insidious onset and progression of symptoms is rare, but is associated with better chance of return of function (especially bladder function).

15. Incidence of CES Incidence of CES in U.S. is estimated between 2 and 4 cases per 10,000 patients with chief complaint which includes LBP. Incidence of CES in U.S. is estimated between 2 and 4 cases per 10,000 patients with chief complaint which includes LBP. Estimated to be present to some degree in as many as 2% of patients undergoing surgery for HNP. Estimated to be present to some degree in as many as 2% of patients undergoing surgery for HNP. High clinical suspicion must be kept in patients presenting with LBP and other symptoms. Good history and physical exam-taking is key! High clinical suspicion must be kept in patients presenting with LBP and other symptoms. Good history and physical exam-taking is key!

16. Possible etiology of injury in CES Herniated lumbar disc Herniated lumbar disc Tumor Tumor Trauma Trauma Spinal epidural hematoma Spinal epidural hematoma Infection Infection Other Other Basic idea: Severe Canal Stenosis (narrowing) Basic idea: Severe Canal Stenosis (narrowing)

17. Pathophysiology of CES Nerve roots of the Cauda Equina are susceptible to injury from compression partly due to a poorly developed epineurium (less protection from “outside stresses” or tension). Nerve roots of the Cauda Equina are susceptible to injury from compression partly due to a poorly developed epineurium (less protection from “outside stresses” or tension). Proximal nerve roots are relatively hypovascularized and are supplemented by increased vascular permeability in this area as well as diffusion from surrounding CSF (which is thought to contribute to swelling and edema in irritated nerve roots). Proximal nerve roots are relatively hypovascularized and are supplemented by increased vascular permeability in this area as well as diffusion from surrounding CSF (which is thought to contribute to swelling and edema in irritated nerve roots).

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

19. Herniated Lumbar Disc in CES Herniation of a [typically] massive portion of intervertebral disc material into the spinal canal causing compression of the descending nerves of the cauda equina. Herniation of a [typically] massive portion of intervertebral disc material into the spinal canal causing compression of the descending nerves of the cauda equina. Represents between 15 and 20% of CES cases. Represents between 15 and 20% of CES cases.

20. Herniated Lumbar Disc in CES Ten cases reported in the literature of CES being caused by very large disc fragment[s] which have migrated into the posterior epidural space causing posterior compression. Ten cases reported in the literature of CES being caused by very large disc fragment[s] which have migrated into the posterior epidural space causing posterior compression. More than 100 cases of reports of intradural migration of herniated disc fragments. More than 100 cases of reports of intradural migration of herniated disc fragments. Some estimates place prevalence of CES as high as 2% of herniated intervertebral discs! Some estimates place prevalence of CES as high as 2% of herniated intervertebral discs!

21. Herniated Lumbar Disc in CES Variability in presentation is a direct result of level of involvement. Variability in presentation is a direct result of level of involvement. Most common level of involvement is L4-5 (57%), followed by L5-S1 (30%), then L3-4 (13%). Most common level of involvement is L4-5 (57%), followed by L5-S1 (30%), then L3-4 (13%). Most common presentation of CES secondary to acute disc herniation is males age 30-40 with prior history of LBP. Most have NOT been operated on previously. Most common presentation of CES secondary to acute disc herniation is males age 30-40 with prior history of LBP. Most have NOT been operated on previously.

22. Primary Tumor in CES Ependymomas account for roughly 90% of primary tumors of the filum terminale and cauda equina, the majority of which (~60%) are of the myxopapillary subtype. Still, CES from this is rare. Ependymomas account for roughly 90% of primary tumors of the filum terminale and cauda equina, the majority of which (~60%) are of the myxopapillary subtype. Still, CES from this is rare. Schwannomas in the area of the conus or cauda equina can also occur and cause CES, but are rare. Schwannomas in the area of the conus or cauda equina can also occur and cause CES, but are rare.

23. Other lesions causing CES Tarlov cysts, while rarely symptomatic, have been described in the literature as causing CES. Tarlov cysts, while rarely symptomatic, have been described in the literature as causing CES. Primary sacral neoplasms, such as chordoma or a destructive bony lesion, can cause CES through collapse of bone and structure. Primary sacral neoplasms, such as chordoma or a destructive bony lesion, can cause CES through collapse of bone and structure. Again, in all cases, the mechanism is compression of the nerve roots. Anything that does this can cause CES. Again, in all cases, the mechanism is compression of the nerve roots. Anything that does this can cause CES.

24. Metastatic Tumor in CES Incidence of spinal metastasis is increasing due to improvements in diagnostic modalities, imaging, and treatment regimens. Incidence of spinal metastasis is increasing due to improvements in diagnostic modalities, imaging, and treatment regimens. The most common non-CNS metastatic tumor causing spinal metastases is lung; however CES occurs in less than 1% of cases involving spinal spread of metastatic lung cancer. The most common non-CNS metastatic tumor causing spinal metastases is lung; however CES occurs in less than 1% of cases involving spinal spread of metastatic lung cancer.

25. Metastatic tumor and CES Drop metastases from inctracranial ependymomas, germinomas, and other primary intraneural tumors can cause CES from seeding via the CSF space. Drop metastases from inctracranial ependymomas, germinomas, and other primary intraneural tumors can cause CES from seeding via the CSF space. Primary genitourinary and gynecologic tumor extension into the cauda equina region has been described. Primary genitourinary and gynecologic tumor extension into the cauda equina region has been described.

26. Trauma in CES Mechanical disruption of the spine from subluxation, sponylolisthesis, and/or compression of the neural elements from hematoma, etc., can cause CES. Mechanical disruption of the spine from subluxation, sponylolisthesis, and/or compression of the neural elements from hematoma, etc., can cause CES. True incidence in the trauma setting is somewhat unclear due to coexisting injuries. True incidence in the trauma setting is somewhat unclear due to coexisting injuries.

27. Other causes of CES Spinal Epidural Hematoma Spinal Epidural Hematoma Infection Infection Again…Anything that leads to compression of the roots. Again…Anything that leads to compression of the roots.

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

29. Prognosis Shapiro et al noted that patients who underwent surgery within 48 hrs of symptom onset, 95% recovered continence and normal function within six months. Conversely, 63% of those patients whose surgery was delayed beyond 48 hrs still required catheterization after 6 months. Shapiro et al noted that patients who underwent surgery within 48 hrs of symptom onset, 95% recovered continence and normal function within six months. Conversely, 63% of those patients whose surgery was delayed beyond 48 hrs still required catheterization after 6 months. Generally, patients show improvement first in pain, then with motor function – while autonomic signs are last to improve (and the least likely). Generally, patients show improvement first in pain, then with motor function – while autonomic signs are last to improve (and the least likely).

30. When to operate A meta-analysis that came out of Johns Hopkins University in 2000 (total 332 patients) that looked at patients with CES secondary to lumbar disc herniations, Ahn et al determined a significant improvement in outcome for patients operated on within 48 hours of onset of symptoms when compared with those operated on more than 48 hours after onset of symptoms. A meta-analysis that came out of Johns Hopkins University in 2000 (total 332 patients) that looked at patients with CES secondary to lumbar disc herniations, Ahn et al determined a significant improvement in outcome for patients operated on within 48 hours of onset of symptoms when compared with those operated on more than 48 hours after onset of symptoms. Within those respective groups, there was no significant difference in outcomes for earlier or later times. Within those respective groups, there was no significant difference in outcomes for earlier or later times.

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

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

33. Current recommendations Current recommendations outline a goal of performing surgery within 24 hours of presentation if at all possible. Current recommendations outline a goal of performing surgery within 24 hours of presentation if at all possible. A major line of thinking behind this plan lies in the medical-legal pitfalls of dealing with CES and the residual deficits dealt with by the patients. A major line of thinking behind this plan lies in the medical-legal pitfalls of dealing with CES and the residual deficits dealt with by the patients.

34. Operating for CES The goal of the operation is to decompress the nerve roots of the cauda equina. The goal of the operation is to decompress the nerve roots of the cauda equina. Instrumentation is rarely used for acute disc herniations, but is more commonly used in cases of CES caused by trauma or severe degenerative disease of the spine from which CES has been the result of instability. Instrumentation is rarely used for acute disc herniations, but is more commonly used in cases of CES caused by trauma or severe degenerative disease of the spine from which CES has been the result of instability.

35. Summary