Cauda equina syndrome in early pregnancy: a case report

This is the authors' abstract. We don't add key points for this paper.

Cauda equina syndrome (CES) is a rare spinal emergency that occurs due to excessive compression of the nerve roots below the level of the spinal cord termination. Only two cases of CES diagnosed during pregnancy have been reported in the literature 1, 2. Classically, CES presents as a complex of low-back pain, bilateral radicular leg pain, saddle anesthesia, bilateral motor weakness and sensory loss in the lower extremities, as well as bowel and bladder dysfunction 3, 4. Magnetic resonance imaging (MRI) is performed urgently when CES is suspected clinically to diagnose and localize the cause of CES, and identify a site for surgical decompression. Emergency decompression is recommended to avoid permanent neurological sequelae 5. We report a case of CES in a 37-year-old woman in the first trimester of pregnancy, due to a prolapsed lumbar disc. CES is a clinical diagnosis, whose cardinal symptoms of weakness, saddle anesthesia, and bowel and bladder dysfunction can be delayed in onset. The management of CES is unchanged in pregnancy 2. A 37-year-old woman (gravidity 3, para 2), 11 weeks pregnant, was admitted to the Emergency Department (E.D.) complaining of acutely severe low back and left leg pain but no weakness or altered sensation. There was no history of trauma and no abdominal pain or per vagina bleeding. She reported intermittent but worsening back pain for 3 months. Her brother had had emergency spinal surgery in the past. On examination, she was apyrexial, and abdomen and pelvis were normal. She had positive nerve root tension signs, evident by straight leg raise, but no sensory or motor deficit and normal anal tone. She was admitted to the E.D. ward overnight for pain relief and observation. The following evening, 21 hours after her arrival in the E.D., the patient complained of numbness in her perianal/buttock region and down the back of both legs, as well as micturition difficulties. Repeat examination confirmed saddle anesthesia and laxity of anal tone. A clinical diagnosis of CES was made and emergency MRI (Figures 1 and 2) of her lumbosacral spine showed a large herniated disc at L4–L5, causing complete canal stenosis and occlusion of both nerve root exit foramina. Emergency lumbar discectomy and decompression surgery relieved cauda equina and nerve root pressure. She regained her motor function, bladder and bowel control in the months following her surgery but continues to have persistent paraesthesia down the back of both legs and anesthesia in her saddle area 18 months later. She has returned to work part-time as an office manager. The remainder of her pregnancy was unremarkable but in view of her history of CES her attending obstetrician opted to perform an elective cesarean section at 39-weeks gestation when she delivered a normal baby boy. He had hypospadias but no other congenital problems and is now a normal healthy 1 year old. Sagittal T2 MRI showing prolapsed L4–L5 disc causing spinal stenosis and severe spinal canal compromise. Axial T2 MRI at L4–L5 level demonstrating the degree of canal compromise and cauda equina compression. CES is a rare spinal emergency that can occur in pregnant patients 1-5. More than 80% of patients have pre-existing chronic low back problems with or without sciatica 3, 4. Lumbar disc prolapse is the commonest cause of CES but it can also occur due to trauma, primary, or metastatic spinal tumors or abscesses, and following spinal anesthesia 3, 4. CES occurs most commonly in the fourth or fifth decades 3, 4. Pregnancy itself is not a risk factor, but a rise in the average age of pregnant mothers may make this clinical scenario more likely. CES is a clinical diagnosis and an emergency MRI is indicated to identify the underlying cause and site for decompression. There are potential risks to the fetus from each of the three types of electromagnetic fields (static, radio-frequency, and time-varying gradients) used to produce images in MRI 6. Exposure to MRI from 20 weeks of gestation does not appear to cause adverse effects on the infant at 9 months follow-up, including no evidence of hearing impairment due to acoustic noise exposure from time-varying gradients 7. Less is known about MRI in the first trimester and it is not recommended because of the theoretical risk of miscarriage from static fields, and potential adverse effects on organogenesis from the elevation of fetal temperature due to radio frequency fields 6. However, as in this spinal emergency, the use of MRI at any stage of pregnancy is warranted when the risk–benefit ratio to the pregnant patient or fetus favors its use and a better alternative does not exist 8. The clinician should be aware that a delay in the development of CES can occur in patients with an acute low back problem. Patients should be given clear advice to report new symptoms, particularly changes in motor weakness, micturition, and bowel incontinence, and re-examined regularly for the development of new neurological deficits. Surgical decompression is recommended within 48 h of the onset of symptoms of CES to reduce permanent neurological damage and improve the patient's long-term outcome 5.

Case report suggests urgent decompression may be feasible in first-trimester cauda equina syndrome; leaves open need for prospective data on outcomes.