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Computerized tomography in diagnosis of compression of the common peroneal nerve by ganglion cysts
Computerized Radio/. Vol. 7, No. 6, pp. 343-345, Printedin the U.S.A. All rightsreserved
0730-4862/83
1983
$3.00 + 0.00
Copyright0 1983PergamonPressLtd
COMPUTERIZED TOMOGRAPHY IN DIAGNOSIS OF COMPRESSION OF THE COMMON PERONEAL NERVE BY GANGLION CYSTS
HOSSEIN FIROOZNIA, CORNELIA GOLIMBU, MAHVASH RAFII
and JEFFREY CHAPNICK
New York University School of Medicine, Department of Radiology, 560 First Avenue, NY 10016, U.S.A. (Received 21 January 1983; received for publication 23 May 1983)
Abstract-A 48-yr old man noted gradual onset of pain, and paresthesia on the lateral aspect of his right leg. The findings were suggestive of ST root compression. CT of spine was normal. Physical examination revealed a small mass overlying the right fibular head. CT revealed this to be a cystic mass. At surgery a ganghon cyst compressing the common peroneal nerve was found. Peripheral nerves may be compressed by ganglia producing a syndrome mimicking central nerve root compression. CT is the modality of choice for detection of these lesions.
Ganglion cysts
Peroneal nerve
Peripheral nerves
Neuropathy
Compression
INTRODUCTION
Compression of a peripheral nerve by a ganglion cyst or other mass cause a clinical syndrome which may resemble very closely that found in spinal nerve root disease. In many cases, localization of the lesion as either definitely central or peripheral is not readily accomplished clinically [l]. Myelography and CT of the spine can help exclude a central lesion with compression of the nerve root at the level of the vertebral column, whereas the evaluation of patients with presumed peripheral lesions has heretofore been primarily surgical in nature, conventional radiography being of limited value in such cases. We report a patient with a ganglion cyst compressing the common peroneal nerve in whom evaluation by CT proved to be very useful.
CASE
REPORT
A 4%yr old man presented to his clinician with the gradual onset, over a period of 3 months of pain, numbness, and paresthesias along the lateral aspect of the right leg. A herniated nucleus pulposus was suspected and a CT of the lumbosacral spine was performed with negative results. Attention then was turned to the lateral side of the right leg on which there was a barely noticeable area of soft tissue swelling at the level of the head of the fibula. Conventional radiography of the knee revealed a small area of homogeneous soft tissue swelling with no evidence of bone destruction. A CT was then performed through the proximal fibula utilizing 5 mm thick slices, spaced 3 mm apart. A 1.7 by 1 cm hypodense rounded cystic structure was noted, laterally adjacent to the fibular head. The cyst had thin walls which were perfectly smooth, and its interior contained a homogeneous density with a CT number of approximately 11 Hounsfield units (water: 0, muscle: 45). There was no evidence of involvement of the underlying fibula. After administration of intravenous contrast, there was no significant enhancement of the lesion, but enhancement of the surrounding normal tissues led to a better delineation of the cyst (Fig. 1). The CT appearance was highly specific for a benign cystic lesion. At surgery, a ganglion cyst was noted adherent to the right common peroneal nerve. Pathologic examination revealed the lesion to be a synovial cyst. 343
344
HOSEIN FIRCXIZNIAet al.
Fig.
xial slice through
proximal metaphysis of tibiae and fibulae reveals a well-delineated (arrow) adjacent to the right fibular neck.
cyst tic density
DISCUSSION Although ganglion cysts are common, they rarely involve the peripheral nerves. According to Stack [l], Hartwell [2], in 1901, was the first to describe peripheral nerve involvement by a ganglion cyst. In his patient, the median nerve was affected. Sultan [3] in 1921, reported a patient with paralysis of the common peroneal nerve caused by a cystic tumor. Since then a large number of cases have been reported [I, 4-121 most of which include involvement of the common peroneal nerve. In 1961, Parkes [9] reported a relatively large series of ganglia involving the common peroneal nerve. He treated eight patients within a period of approximately 6 years and concluded that this problem was not rare. The exact pathogenesis of the ganglion cyst of the common peroneal nerve is not known. According to Parkes [9] ganglia of the common peroneal nerve arise from the proximal tibio-fibular joint, and then extent along the sheath of the small recurrent superior tibio-fibular articular branch of the common peroneal nerve to the main nerve. Once the ganglion has arrived at the main sheath, situating itself within it, marked enlargement and cystic degeneration can take place. Some authors [5,7, 1l] have suggested that the ganglia may merely represent cystic degeneration of the nerve sheath. Compression of the peripheral nerves by ganglion cysts can strongly mimic central nerve root compression. The diagnosis is not suspected unless one is aware of the entity. There are reports of laminectomies having been performed on patients with peroneal nerve ganglion cysts on the basis of clinical findings and equivocal myelography results [l]. The initial complaint is usually pain, which is first localized to the upper lateral aspect of the leg and then may be referred downward and over the dorsum of the foot and toes. The pain can occur anywhere along the distribution of the cutaneous supply of the peroneus nerve. Varying degrees of paresis of the muscles supplied by the common peroneal nerve is also usually present. A small mass, postero-laterally adjacent to the neck of the fibula, may be the presenting symptom. It may be asymptomatic for a number of months or years. In approximately 20% of the patients, a palpable mass may not be present. Up to now, surgical exploration was necessary to either confirm or rule out this possibility. CT is currently the modality of choice for the detection and a precise localization of soft tissue tumors because of its ability to display the anatomy in an axial plane, and to distinguish between small differences in the attenuation of various soft tissue components. We believe that high resolution CT of the proximal leg, utilizing consecutive 3-5 mm thick slices, should be performed whenever this condition is suspected. Treatment consists of surgical resection of the cyst as completely as possible, with care to avoid damage to the nerve. Sacrifice of nerve fibers to obtain complete excision is not necessary. Stack [l]
CT in diagnosis
of compression
of common
peroneal
345
nerve
did not observe recurrence of the cyst after complete excision, nor have we found such in the reports of others. SUMMARY Compression of the peripheral nerves by a ganglion cyst or other mass can produce a clinical syndrome closely resembling spinal nerve neuropathy. Ganglion cysts are commonly encountered; however, compression of the peripheral nerves by them is uncommon. A 4%yr old patient is described with findings suggestive of S 1 neuropathy due to a ganglion cyst. CT revealed a well-delineated cystic structure adjacent to the fibular head. This proved to be a ganglion cyst at surgery. Ganglion cysts of the common peroneal nerve arise from the proximal tibiofibular joint and extend along the sheath of the small recurrent superior tibia-fibular articular branch of the common peroneal nerve to the main nerve. The ganglion cyst then dissects within the nerve sheath producing marked enlargement and cystic degeneration. Some believe the ganglia may merely represent cystic degeneration of the nerve sheath. Up to now, surgical exploration was necessary for a definitive diagnosis of this condition. High-resolution CT is currently the modality of choice for evaluation of soft tissue masses, and we believe is the ideal modality for detection of these lesions. Treatment consists of surgical resection of the cyst as completely as possible, without sacrifice of the nerve. Recurrence is rare. REFERENCES 1. R. E. Stack, A. J. Younku Jr and C. S. McCarthy, Compression of the common peroneal nerve by ganglion cysts: report of nine cases, J. Bone Joint Surg. 47A, 773-778 (1965). 2. A. S. Hartwell, Cystic tumor of median nerve; operation: restoration and function, Boston Med. Surg. J. 144, 582-583 (1901). 3. C. Sultan, Ganglion der Nervenscheide des Nervus Peroneus, Zentrulbl. F. Chir. 48, 963-965 (1921). by simple ganglia. A review of thirteen collected cases, J. Bone Joint Surg. 34B, 391400 4. D. M. Brooks, Nerve compression (1952). 5. K. Clark, Ganglion of the lateral popliteal nerve, J. Bone Joint Surg. 43B, 778-783 (1961). 6. V. H. Ellis, Two cases of ganglia in the sheath of the peroneal nerve, Br. J. Surg. 24, 141-142 (193637). 7. L. K. Ferguson, Ganglion of the peroneal nerve, Ann. Surg. 106, 313-316 (1937). 8. S. A. Jenkins, Solitary tumors of peripheral nerve trunks, J. Bone Joint Surg. 34B 401411 (1952). 9. A. Parkes, Intraneural ganglion of the lateral popliteal nerve, J. Bone Joint Surg. 43B, 784-790 (1961). 10. G. S. Tupman, Axonotmesis of anterior tibia1 branch of lateral popliteal nerve due to ganglion of the nerve-sheath, Br. J. Surg. 45, 23-24 (1957). 11. T. Wadstein, Two cases of ganglia in the sheath of the peroneal nerve, Acfa orthop. stand. 2, 221-231 (1931). 12. R. Warren, Ganglion of the common peroneal nerve. Case report, Ann. Surg. 124, 152-155 (1946).
About the Autbor-HOSSEIN
FIRIXZNIA received his M.D. in 1962 from Tehran University School of Medicine. He was a resident in radiology in New York University Medical Center, 19641967. At present, he is Professor of Clinical Radiology at New York University Medical Center.
About the Author-CORNELIA
GOLIMBU received her M.D. in 1963 from Bucharest Medical School. She was a resident in radiology at Manhattan Veteran Administration Hospital from 1971 to 1974. At present she is Assistant Professor of Radiology at New York University Medical Center.. About the Author-MAHVASH
RAF11received her M.D. from Tehran University Medical School in 1969. Her radiology training includes 3 years of residency at the New England Deaconess Hospital of Boston, and 1 year of fellowship at St Vincent’s Hospital of Manhattan. At present she is Assistant Professor of Radiology at the New York University Medical Center. About the Author-JEFFREY
CHAPNICK received
presently
in Radiology
a Senior
Resident
his M.D. in 1979 from Downstate Medical at the New York University Medical Center.
School.
He is
0730-4862/83
1983
$3.00 + 0.00
Copyright0 1983PergamonPressLtd
COMPUTERIZED TOMOGRAPHY IN DIAGNOSIS OF COMPRESSION OF THE COMMON PERONEAL NERVE BY GANGLION CYSTS
HOSSEIN FIROOZNIA, CORNELIA GOLIMBU, MAHVASH RAFII
and JEFFREY CHAPNICK
New York University School of Medicine, Department of Radiology, 560 First Avenue, NY 10016, U.S.A. (Received 21 January 1983; received for publication 23 May 1983)
Abstract-A 48-yr old man noted gradual onset of pain, and paresthesia on the lateral aspect of his right leg. The findings were suggestive of ST root compression. CT of spine was normal. Physical examination revealed a small mass overlying the right fibular head. CT revealed this to be a cystic mass. At surgery a ganghon cyst compressing the common peroneal nerve was found. Peripheral nerves may be compressed by ganglia producing a syndrome mimicking central nerve root compression. CT is the modality of choice for detection of these lesions.
Ganglion cysts
Peroneal nerve
Peripheral nerves
Neuropathy
Compression
INTRODUCTION
Compression of a peripheral nerve by a ganglion cyst or other mass cause a clinical syndrome which may resemble very closely that found in spinal nerve root disease. In many cases, localization of the lesion as either definitely central or peripheral is not readily accomplished clinically [l]. Myelography and CT of the spine can help exclude a central lesion with compression of the nerve root at the level of the vertebral column, whereas the evaluation of patients with presumed peripheral lesions has heretofore been primarily surgical in nature, conventional radiography being of limited value in such cases. We report a patient with a ganglion cyst compressing the common peroneal nerve in whom evaluation by CT proved to be very useful.
CASE
REPORT
A 4%yr old man presented to his clinician with the gradual onset, over a period of 3 months of pain, numbness, and paresthesias along the lateral aspect of the right leg. A herniated nucleus pulposus was suspected and a CT of the lumbosacral spine was performed with negative results. Attention then was turned to the lateral side of the right leg on which there was a barely noticeable area of soft tissue swelling at the level of the head of the fibula. Conventional radiography of the knee revealed a small area of homogeneous soft tissue swelling with no evidence of bone destruction. A CT was then performed through the proximal fibula utilizing 5 mm thick slices, spaced 3 mm apart. A 1.7 by 1 cm hypodense rounded cystic structure was noted, laterally adjacent to the fibular head. The cyst had thin walls which were perfectly smooth, and its interior contained a homogeneous density with a CT number of approximately 11 Hounsfield units (water: 0, muscle: 45). There was no evidence of involvement of the underlying fibula. After administration of intravenous contrast, there was no significant enhancement of the lesion, but enhancement of the surrounding normal tissues led to a better delineation of the cyst (Fig. 1). The CT appearance was highly specific for a benign cystic lesion. At surgery, a ganglion cyst was noted adherent to the right common peroneal nerve. Pathologic examination revealed the lesion to be a synovial cyst. 343
344
HOSEIN FIRCXIZNIAet al.
Fig.
xial slice through
proximal metaphysis of tibiae and fibulae reveals a well-delineated (arrow) adjacent to the right fibular neck.
cyst tic density
DISCUSSION Although ganglion cysts are common, they rarely involve the peripheral nerves. According to Stack [l], Hartwell [2], in 1901, was the first to describe peripheral nerve involvement by a ganglion cyst. In his patient, the median nerve was affected. Sultan [3] in 1921, reported a patient with paralysis of the common peroneal nerve caused by a cystic tumor. Since then a large number of cases have been reported [I, 4-121 most of which include involvement of the common peroneal nerve. In 1961, Parkes [9] reported a relatively large series of ganglia involving the common peroneal nerve. He treated eight patients within a period of approximately 6 years and concluded that this problem was not rare. The exact pathogenesis of the ganglion cyst of the common peroneal nerve is not known. According to Parkes [9] ganglia of the common peroneal nerve arise from the proximal tibio-fibular joint, and then extent along the sheath of the small recurrent superior tibio-fibular articular branch of the common peroneal nerve to the main nerve. Once the ganglion has arrived at the main sheath, situating itself within it, marked enlargement and cystic degeneration can take place. Some authors [5,7, 1l] have suggested that the ganglia may merely represent cystic degeneration of the nerve sheath. Compression of the peripheral nerves by ganglion cysts can strongly mimic central nerve root compression. The diagnosis is not suspected unless one is aware of the entity. There are reports of laminectomies having been performed on patients with peroneal nerve ganglion cysts on the basis of clinical findings and equivocal myelography results [l]. The initial complaint is usually pain, which is first localized to the upper lateral aspect of the leg and then may be referred downward and over the dorsum of the foot and toes. The pain can occur anywhere along the distribution of the cutaneous supply of the peroneus nerve. Varying degrees of paresis of the muscles supplied by the common peroneal nerve is also usually present. A small mass, postero-laterally adjacent to the neck of the fibula, may be the presenting symptom. It may be asymptomatic for a number of months or years. In approximately 20% of the patients, a palpable mass may not be present. Up to now, surgical exploration was necessary to either confirm or rule out this possibility. CT is currently the modality of choice for the detection and a precise localization of soft tissue tumors because of its ability to display the anatomy in an axial plane, and to distinguish between small differences in the attenuation of various soft tissue components. We believe that high resolution CT of the proximal leg, utilizing consecutive 3-5 mm thick slices, should be performed whenever this condition is suspected. Treatment consists of surgical resection of the cyst as completely as possible, with care to avoid damage to the nerve. Sacrifice of nerve fibers to obtain complete excision is not necessary. Stack [l]
CT in diagnosis
of compression
of common
peroneal
345
nerve
did not observe recurrence of the cyst after complete excision, nor have we found such in the reports of others. SUMMARY Compression of the peripheral nerves by a ganglion cyst or other mass can produce a clinical syndrome closely resembling spinal nerve neuropathy. Ganglion cysts are commonly encountered; however, compression of the peripheral nerves by them is uncommon. A 4%yr old patient is described with findings suggestive of S 1 neuropathy due to a ganglion cyst. CT revealed a well-delineated cystic structure adjacent to the fibular head. This proved to be a ganglion cyst at surgery. Ganglion cysts of the common peroneal nerve arise from the proximal tibiofibular joint and extend along the sheath of the small recurrent superior tibia-fibular articular branch of the common peroneal nerve to the main nerve. The ganglion cyst then dissects within the nerve sheath producing marked enlargement and cystic degeneration. Some believe the ganglia may merely represent cystic degeneration of the nerve sheath. Up to now, surgical exploration was necessary for a definitive diagnosis of this condition. High-resolution CT is currently the modality of choice for evaluation of soft tissue masses, and we believe is the ideal modality for detection of these lesions. Treatment consists of surgical resection of the cyst as completely as possible, without sacrifice of the nerve. Recurrence is rare. REFERENCES 1. R. E. Stack, A. J. Younku Jr and C. S. McCarthy, Compression of the common peroneal nerve by ganglion cysts: report of nine cases, J. Bone Joint Surg. 47A, 773-778 (1965). 2. A. S. Hartwell, Cystic tumor of median nerve; operation: restoration and function, Boston Med. Surg. J. 144, 582-583 (1901). 3. C. Sultan, Ganglion der Nervenscheide des Nervus Peroneus, Zentrulbl. F. Chir. 48, 963-965 (1921). by simple ganglia. A review of thirteen collected cases, J. Bone Joint Surg. 34B, 391400 4. D. M. Brooks, Nerve compression (1952). 5. K. Clark, Ganglion of the lateral popliteal nerve, J. Bone Joint Surg. 43B, 778-783 (1961). 6. V. H. Ellis, Two cases of ganglia in the sheath of the peroneal nerve, Br. J. Surg. 24, 141-142 (193637). 7. L. K. Ferguson, Ganglion of the peroneal nerve, Ann. Surg. 106, 313-316 (1937). 8. S. A. Jenkins, Solitary tumors of peripheral nerve trunks, J. Bone Joint Surg. 34B 401411 (1952). 9. A. Parkes, Intraneural ganglion of the lateral popliteal nerve, J. Bone Joint Surg. 43B, 784-790 (1961). 10. G. S. Tupman, Axonotmesis of anterior tibia1 branch of lateral popliteal nerve due to ganglion of the nerve-sheath, Br. J. Surg. 45, 23-24 (1957). 11. T. Wadstein, Two cases of ganglia in the sheath of the peroneal nerve, Acfa orthop. stand. 2, 221-231 (1931). 12. R. Warren, Ganglion of the common peroneal nerve. Case report, Ann. Surg. 124, 152-155 (1946).
About the Autbor-HOSSEIN
FIRIXZNIA received his M.D. in 1962 from Tehran University School of Medicine. He was a resident in radiology in New York University Medical Center, 19641967. At present, he is Professor of Clinical Radiology at New York University Medical Center.
About the Author-CORNELIA
GOLIMBU received her M.D. in 1963 from Bucharest Medical School. She was a resident in radiology at Manhattan Veteran Administration Hospital from 1971 to 1974. At present she is Assistant Professor of Radiology at New York University Medical Center.. About the Author-MAHVASH
RAF11received her M.D. from Tehran University Medical School in 1969. Her radiology training includes 3 years of residency at the New England Deaconess Hospital of Boston, and 1 year of fellowship at St Vincent’s Hospital of Manhattan. At present she is Assistant Professor of Radiology at the New York University Medical Center. About the Author-JEFFREY
CHAPNICK received
presently
in Radiology
a Senior
Resident
his M.D. in 1979 from Downstate Medical at the New York University Medical Center.
School.
He is