Original Paper Eur Neurol 1992:32:267-269
Neurologische Klinik, Neurochirurgische Klinik, und Abteilung für Medizinische Radiologie. Kantonsspital, Basel. Schweiz
KeyWords
Erectile dysfunction Bulbocavernosus reflex Somatosensory evoked potentials Cauda equina
Lipoma of the Cauda equina Selectively Involving Lower Sacral Roots Case Report
Abstract
A 44-year-old male patient suffering from sexual and voiding dysfunction did not exhibit any sensorimotor deficit except for a lax anal sphincter with loss of the bulbocavernosus reflex (BCR). The absence of both the electrically induced BCR and cortical evoked responses to stimulation of the dorsal penile nerve as well as partial denervation of the pelvic floor musculature suggested damage to the lower sacral roots. The site of the lesion as indicated by electrophysiological findings was confirmed by computerized tomography and mag netic resonance imaging. The operation revealed a lipoma involving a few cauda fibers which produced a distension in the region of the conus medullaris.
Introduction
Patient Report
Today, the clinical evaluation of impotent men is sup ported by a variety of laboratory tests with special empha sis on the neurologic aspects of erectile dysfunction. Electrophysiological methods such as the bulbocavernosus reflex (BCR) and somatosensory evoked potentials (SSEPs) with stimulation of the pudendal nerve provide objective information as to the integrity of afferent and efferent pathways [1-6] even if peripheral nerves are subclinically involved [7], We describe a patient who did exhibit minor neurological deficits but whose examina tion by neurophysiological techniques led to the detection of a lipoma involving the cauda equina.
Received: June 3.1991 Accepted: August 26, 1991
The 44-year-old male patient suffering from episodic dizziness was admitted to the E M G laboratory for clectrodiagnostic testing in November 1989 on the suspicion o f multiple sclerosis. Erectile dys function (i.e. insufficient penile rigidity) progressively evolving for about 4 years and the inability to ejaculate were his major complaints while there was no past history o f sciatica or neurological deficits in his lower limbs. I f questioned carefully, the patient confessed an increase in daytime urinary frequency, a ‘stress' incontinence o f urine as well as the inadvertent passage o f formed feces at night once in the past. Except for a lax anal sphincter with loss o f the BCR the neurological examination did not reveal any sensorimotor deficit, especially no sensory impairment in the lower sacral dermatomas. Pattern reversal visual evoked responses, brainstem auditory evoked responses as well as spinal and scalp recorded SSEPs by stimulating both the median nerve at the wrist and the posterior tibial nerve at the ankle were within normal limits. In addition, the electrically induced B C R and cortical evoked responses to stimulation o f the dorsal penile nerve were investigated. Square wave stimuli o f 0.2-ms duration were applied at a frequency o f 3 Hz by ring electrodes attached to the base o f the penis. Stimulus intensity was kept con-
Waller G . Fricdli E M G Labor. Neurologische Universitätsklinik Kantonsspital CH-4031 Basel (Switzerland)
© 1992 S. Karger A G . Basel 0014-3022/92/0325-0267 S2.75/0
Downloaded by: Univ. of California Santa Barbara 128.111.121.54 - 4/5/2018 12:55:51 PM
Walter G. Friedlia Otmar Gratzlh Ernst W. Radüc
stant at 3 times sensory threshold. Pudendal SSEPs were recorded by needle electrodes applied to the scalp at C z and Fpz (10-20 system), amplified (0.5 Hz to 3 kHz) and 1,000 samples were averaged twice for a sampling period o f 100 ms. By using single shocks o f 6 times sensory threshold the B CR was recorded by a concentric needle elec trode from the bulbocavernosus muscle behind the scrotum on both sides. Despite the normal SSEPs following stimulation o f the poste rior tibial nerve there were neither cortical pudendal SSEPs nor a reflex response recorded in the pelvic floor musculature (fig. I). However, electromyography o f the latter indicated partial denerva tion on both sides as characterized by fibrillations and positive sharp waves, an increase in the number o f polyphasic potentials with the mean duration o f action potentials being increased. Cystography revealed a high bladder capacity o f 700 ml although the patient did not report any urge or desire to void during filling. The residual urine volume was 500 ml and the findings o f cystometry were consistent with a neurogenic bladder due to a sensorimotor peripheral nervous lesion. The presence o f any systemic disease such as diabetes mcllitus, renal insufficiency, endocrine dysfunction or liver disease was excluded by laboratory testing. Computerized tomography (CT) revealed a roundish, low'-densitv tumor which spread lengthwise in the region o f the lumbar vertebrae L I-L 3 . Magnetic resonance imag ing (M RI) showed a signal-enriched zone in the Tl-weighted layers which was localized in the central area o f the cauda equina at the level o f L2 (fig. 2). Mvelographicallv no obstruction in the flow o f the contrast medium was observed. The protein content (0.471 g/l) as well as the albumin fraction o f the cerebrospinal fluid were within the upper limits; the gamma globulin pattern was normal without dem onstration o f oligoclonal bands. There was no elevation o f white cells in the cerebrospinal fluid (0.7 X 106/l). A laminectomy o f L I and L2 was carried out under general anesthesia. With the use o f the operat ing microscope the dura was opened. A yellowish protruding mass became immediately evident. It was a fat tumor (lipoma) which was firmly attached to the filum terminale and also showed adhcrences to the blood vessels o f the filum as well as to two cauda fibers. The lipoma produced a distension in the region o f the conus medullaris. The extremely adherent tissue was only incompletely mobilized in order not to injure the nerval structures and therefore only a partial removal was possible. Histologically the removed tissue showed alveolar structures with sporadic capillary and round cell elements, being consistent with a lipoma. Within 6 months after the operation the patient reported an improvement o f both his erectile and ejacula tory function. However, his residual urine volume was still 400 ml. although the patient experienced a decreased frequency o f urination with an increase o f single portions.
S S E P Dorsal penile nerve p4 0 N 5 0
C
Fig. 1. Cortical somatosensory evoked responses with stimula tion o f the dorsal penile nerve in our patient (A) compared to that o f a 45-vear-old man without erectile dysfunction (B). With stimulation o f the posterior tibial nerve at the ankle normal responses were recorded in the patient cortically at Cz-Fpz and at Th 12/L l with a reference on the anterior-superior iliac spine (C).
Discussion
268
Friedli/Gratzl/Radii
Fig. 2. M R I. A Sagittal Tl-weighted images with an elongated area o f high signal in the upper lumbar region with little space occupying effect. B The signal increases in intensity to a greater degree than the cerebrospinal fluid in T2-wcighted images.
Lipoma of Cauda equina
Downloaded by: Univ. of California Santa Barbara 128.111.121.54 - 4/5/2018 12:55:51 PM
As illustrated by our patient, the lesion responsible for his sexual and voiding dysfunction could be localized on the basis of electrophysiological findings. Although there was no sensory' impairment of the skin of the genitalia and perineum, cortical responses were not recorded with stim ulation of the dorsal penile nerve. On the other hand, the lack o f neurological deficits in the lower limbs was in accordance w'ith normal spinal and scalp recorded SSEPs
by stimulating the posterior tibial nerve at the ankle on either side. In view of the wide spectrum of lower lumbar root supply to the latter these findings indicated a welldefined lesion involving the distal sacral roots on both sides. While the external anal sphincter obtains its inner vation from inferior rectal branches of the pudendal nerves, the striated pelvic floor sphincter muscles are innervated by branches of the S2 and S3 sacral motor roots [8], Hence, bilateral denervation of the bulbocavernosus muscle as well as the absence of the BCR in our patient also suggested a lesion of the lower sacral motor nerve roots arising from the conus mcdullaris at the thora columbar vertebral level. Our conclusions concerning the anatomical site of the lesion as drawn from electrophysiological findings were confirmed by MRI and C T . Intraoperatively, a few distal roots close to the filum terminale adjacent to the conus medullaris were involved while the
latter was invaded by the lipoma. For this reason, the total extirpation of the tumor was not feasible without taking the risk of additional damage to the patient. After exam ining both BCR and pudendal SSEPs in 300 unselected men with erectile dysfunction, we feel that the latter often may be due to multiple factors such as psychogenic, vas cular and neurologic abnormalities in one and the same patient. This is in accordance with previous results [9]. However, as illustrated by the present case, the electro diagnostic tests prove to be a valid supplement to the clin ical examination for the diagnosis of ‘neurogenic’ impo tence. Acknowledgement We wish to thank Mrs. K . Hauser and Mrs. V . Kühl for their help in preparing the manuscript.
References
2
3
Ertekin C . Reel F: Bulbocavernosus reflex in normal men and in patients with neurogenic bladder and/or impotence. J Neurol Sci 1976: 28:1-15. Blaivas J G . Zayed A A , Labib KB: The bulbo cavernosus reflex in urology: A prospective study o f 299 patients. J Urol 1981; 126:197— 199.' Herman C W . Weinberg H J. Brown J: Testing for neurogenic impotence: A challenge. Urol ogy 1986:27:318-321.
4
5
6
Haldeman S. Bradley W E. Bhalia N N , Johnson BK: Pudendal evoked responses. Arch Neurol 1982;39:280-283. Ertekin C . Akyürekli O . Gürses A N . Turgul H: The value o f somatosensory evoked potentials and bulbocavernosus reflex in patients with impotence. Acta Neurol Scand 1985:71:4853. Tackmann W . Vogel P. Porst H: Somatosen sory evoked potentials after stimulation o f the dorsal penile nerve: Normative data and results from 145 patients with erectile dysfunction. Eur Neurol 1987:27:245-250.
7
8
9
Ertekin C . Mutlu R , Sarica Y , Uckardesler L: Electrophysiological evaluation o f the afferent spinal roots and nerves in patients with conus medullaris and cauda equina lesions. J Neurol Sci 1980;48:419-433. Percy JP . Swash M . Neill M E . Parks A G : Elcctrophvsiological study o f motor nerve supply o f pelvic floor. Lancet 1981:i: 16-17. Blaivas J G . O'Donnell T F , Gottlieb P. Labib KB: Comprehensive laboratory evaluation o f impotent men. J Urol 1980;124:201-204.
269
Downloaded by: Univ. of California Santa Barbara 128.111.121.54 - 4/5/2018 12:55:51 PM
1
Neurologische Klinik, Neurochirurgische Klinik, und Abteilung für Medizinische Radiologie. Kantonsspital, Basel. Schweiz
KeyWords
Erectile dysfunction Bulbocavernosus reflex Somatosensory evoked potentials Cauda equina
Lipoma of the Cauda equina Selectively Involving Lower Sacral Roots Case Report
Abstract
A 44-year-old male patient suffering from sexual and voiding dysfunction did not exhibit any sensorimotor deficit except for a lax anal sphincter with loss of the bulbocavernosus reflex (BCR). The absence of both the electrically induced BCR and cortical evoked responses to stimulation of the dorsal penile nerve as well as partial denervation of the pelvic floor musculature suggested damage to the lower sacral roots. The site of the lesion as indicated by electrophysiological findings was confirmed by computerized tomography and mag netic resonance imaging. The operation revealed a lipoma involving a few cauda fibers which produced a distension in the region of the conus medullaris.
Introduction
Patient Report
Today, the clinical evaluation of impotent men is sup ported by a variety of laboratory tests with special empha sis on the neurologic aspects of erectile dysfunction. Electrophysiological methods such as the bulbocavernosus reflex (BCR) and somatosensory evoked potentials (SSEPs) with stimulation of the pudendal nerve provide objective information as to the integrity of afferent and efferent pathways [1-6] even if peripheral nerves are subclinically involved [7], We describe a patient who did exhibit minor neurological deficits but whose examina tion by neurophysiological techniques led to the detection of a lipoma involving the cauda equina.
Received: June 3.1991 Accepted: August 26, 1991
The 44-year-old male patient suffering from episodic dizziness was admitted to the E M G laboratory for clectrodiagnostic testing in November 1989 on the suspicion o f multiple sclerosis. Erectile dys function (i.e. insufficient penile rigidity) progressively evolving for about 4 years and the inability to ejaculate were his major complaints while there was no past history o f sciatica or neurological deficits in his lower limbs. I f questioned carefully, the patient confessed an increase in daytime urinary frequency, a ‘stress' incontinence o f urine as well as the inadvertent passage o f formed feces at night once in the past. Except for a lax anal sphincter with loss o f the BCR the neurological examination did not reveal any sensorimotor deficit, especially no sensory impairment in the lower sacral dermatomas. Pattern reversal visual evoked responses, brainstem auditory evoked responses as well as spinal and scalp recorded SSEPs by stimulating both the median nerve at the wrist and the posterior tibial nerve at the ankle were within normal limits. In addition, the electrically induced B C R and cortical evoked responses to stimulation o f the dorsal penile nerve were investigated. Square wave stimuli o f 0.2-ms duration were applied at a frequency o f 3 Hz by ring electrodes attached to the base o f the penis. Stimulus intensity was kept con-
Waller G . Fricdli E M G Labor. Neurologische Universitätsklinik Kantonsspital CH-4031 Basel (Switzerland)
© 1992 S. Karger A G . Basel 0014-3022/92/0325-0267 S2.75/0
Downloaded by: Univ. of California Santa Barbara 128.111.121.54 - 4/5/2018 12:55:51 PM
Walter G. Friedlia Otmar Gratzlh Ernst W. Radüc
stant at 3 times sensory threshold. Pudendal SSEPs were recorded by needle electrodes applied to the scalp at C z and Fpz (10-20 system), amplified (0.5 Hz to 3 kHz) and 1,000 samples were averaged twice for a sampling period o f 100 ms. By using single shocks o f 6 times sensory threshold the B CR was recorded by a concentric needle elec trode from the bulbocavernosus muscle behind the scrotum on both sides. Despite the normal SSEPs following stimulation o f the poste rior tibial nerve there were neither cortical pudendal SSEPs nor a reflex response recorded in the pelvic floor musculature (fig. I). However, electromyography o f the latter indicated partial denerva tion on both sides as characterized by fibrillations and positive sharp waves, an increase in the number o f polyphasic potentials with the mean duration o f action potentials being increased. Cystography revealed a high bladder capacity o f 700 ml although the patient did not report any urge or desire to void during filling. The residual urine volume was 500 ml and the findings o f cystometry were consistent with a neurogenic bladder due to a sensorimotor peripheral nervous lesion. The presence o f any systemic disease such as diabetes mcllitus, renal insufficiency, endocrine dysfunction or liver disease was excluded by laboratory testing. Computerized tomography (CT) revealed a roundish, low'-densitv tumor which spread lengthwise in the region o f the lumbar vertebrae L I-L 3 . Magnetic resonance imag ing (M RI) showed a signal-enriched zone in the Tl-weighted layers which was localized in the central area o f the cauda equina at the level o f L2 (fig. 2). Mvelographicallv no obstruction in the flow o f the contrast medium was observed. The protein content (0.471 g/l) as well as the albumin fraction o f the cerebrospinal fluid were within the upper limits; the gamma globulin pattern was normal without dem onstration o f oligoclonal bands. There was no elevation o f white cells in the cerebrospinal fluid (0.7 X 106/l). A laminectomy o f L I and L2 was carried out under general anesthesia. With the use o f the operat ing microscope the dura was opened. A yellowish protruding mass became immediately evident. It was a fat tumor (lipoma) which was firmly attached to the filum terminale and also showed adhcrences to the blood vessels o f the filum as well as to two cauda fibers. The lipoma produced a distension in the region o f the conus medullaris. The extremely adherent tissue was only incompletely mobilized in order not to injure the nerval structures and therefore only a partial removal was possible. Histologically the removed tissue showed alveolar structures with sporadic capillary and round cell elements, being consistent with a lipoma. Within 6 months after the operation the patient reported an improvement o f both his erectile and ejacula tory function. However, his residual urine volume was still 400 ml. although the patient experienced a decreased frequency o f urination with an increase o f single portions.
S S E P Dorsal penile nerve p4 0 N 5 0
C
Fig. 1. Cortical somatosensory evoked responses with stimula tion o f the dorsal penile nerve in our patient (A) compared to that o f a 45-vear-old man without erectile dysfunction (B). With stimulation o f the posterior tibial nerve at the ankle normal responses were recorded in the patient cortically at Cz-Fpz and at Th 12/L l with a reference on the anterior-superior iliac spine (C).
Discussion
268
Friedli/Gratzl/Radii
Fig. 2. M R I. A Sagittal Tl-weighted images with an elongated area o f high signal in the upper lumbar region with little space occupying effect. B The signal increases in intensity to a greater degree than the cerebrospinal fluid in T2-wcighted images.
Lipoma of Cauda equina
Downloaded by: Univ. of California Santa Barbara 128.111.121.54 - 4/5/2018 12:55:51 PM
As illustrated by our patient, the lesion responsible for his sexual and voiding dysfunction could be localized on the basis of electrophysiological findings. Although there was no sensory' impairment of the skin of the genitalia and perineum, cortical responses were not recorded with stim ulation of the dorsal penile nerve. On the other hand, the lack o f neurological deficits in the lower limbs was in accordance w'ith normal spinal and scalp recorded SSEPs
by stimulating the posterior tibial nerve at the ankle on either side. In view of the wide spectrum of lower lumbar root supply to the latter these findings indicated a welldefined lesion involving the distal sacral roots on both sides. While the external anal sphincter obtains its inner vation from inferior rectal branches of the pudendal nerves, the striated pelvic floor sphincter muscles are innervated by branches of the S2 and S3 sacral motor roots [8], Hence, bilateral denervation of the bulbocavernosus muscle as well as the absence of the BCR in our patient also suggested a lesion of the lower sacral motor nerve roots arising from the conus mcdullaris at the thora columbar vertebral level. Our conclusions concerning the anatomical site of the lesion as drawn from electrophysiological findings were confirmed by MRI and C T . Intraoperatively, a few distal roots close to the filum terminale adjacent to the conus medullaris were involved while the
latter was invaded by the lipoma. For this reason, the total extirpation of the tumor was not feasible without taking the risk of additional damage to the patient. After exam ining both BCR and pudendal SSEPs in 300 unselected men with erectile dysfunction, we feel that the latter often may be due to multiple factors such as psychogenic, vas cular and neurologic abnormalities in one and the same patient. This is in accordance with previous results [9]. However, as illustrated by the present case, the electro diagnostic tests prove to be a valid supplement to the clin ical examination for the diagnosis of ‘neurogenic’ impo tence. Acknowledgement We wish to thank Mrs. K . Hauser and Mrs. V . Kühl for their help in preparing the manuscript.
References
2
3
Ertekin C . Reel F: Bulbocavernosus reflex in normal men and in patients with neurogenic bladder and/or impotence. J Neurol Sci 1976: 28:1-15. Blaivas J G . Zayed A A , Labib KB: The bulbo cavernosus reflex in urology: A prospective study o f 299 patients. J Urol 1981; 126:197— 199.' Herman C W . Weinberg H J. Brown J: Testing for neurogenic impotence: A challenge. Urol ogy 1986:27:318-321.
4
5
6
Haldeman S. Bradley W E. Bhalia N N , Johnson BK: Pudendal evoked responses. Arch Neurol 1982;39:280-283. Ertekin C . Akyürekli O . Gürses A N . Turgul H: The value o f somatosensory evoked potentials and bulbocavernosus reflex in patients with impotence. Acta Neurol Scand 1985:71:4853. Tackmann W . Vogel P. Porst H: Somatosen sory evoked potentials after stimulation o f the dorsal penile nerve: Normative data and results from 145 patients with erectile dysfunction. Eur Neurol 1987:27:245-250.
7
8
9
Ertekin C . Mutlu R , Sarica Y , Uckardesler L: Electrophysiological evaluation o f the afferent spinal roots and nerves in patients with conus medullaris and cauda equina lesions. J Neurol Sci 1980;48:419-433. Percy JP . Swash M . Neill M E . Parks A G : Elcctrophvsiological study o f motor nerve supply o f pelvic floor. Lancet 1981:i: 16-17. Blaivas J G . O'Donnell T F , Gottlieb P. Labib KB: Comprehensive laboratory evaluation o f impotent men. J Urol 1980;124:201-204.
269
Downloaded by: Univ. of California Santa Barbara 128.111.121.54 - 4/5/2018 12:55:51 PM
1
