Skeletal Radiol DOI 10.1007/s00256-014-2030-3
CASE REPORT
Spontaneous intraneural hematoma of the sural nerve Shawn S. Richardson & Alexander S. McLawhorn & Douglas N. Mintz & Edward F. DiCarlo & Andrew J. Weiland
Received: 22 July 2014 / Revised: 28 September 2014 / Accepted: 1 October 2014 # ISS 2014
Abstract Symptomatic intraneural hemorrhage occurs rarely. It presents with pain and/or weakness in the distribution following the anatomic innervation pattern of the involved nerve. When a purely sensory nerve is affected, the symptoms can be subtle. We present a previously healthy 36-year-old female who developed an atraumatic, spontaneous intraneural hematoma of her sural nerve. Sural dysfunction was elicited from the patient’s history and physical examination. The diagnosis was confirmed with magnetic resonance imaging, and surgical decompression provided successful resolution of her preoperative symptoms. To our knowledge, this entity has not been reported previously. Our case highlights the importance of having a high index of suspicion for nerve injury or compression in patients whose complaints follow a typical peripheral nerve distribution. Prior studies have shown that the formation of intraneural hematoma and associated compression of nerve fibers result in axonal degeneration, and surgical decompression decreases axonal degeneration and aids functional recovery. Keywords Hematoma . Magnetic resonance imaging . Microsurgery . Neuropathy . Sural nerve S. S. Richardson (*) : A. S. McLawhorn Orthopaedic Surgery Resident, Hospital for Special Surgery, 535 East 70th Street, New York, NY 10021, USA e-mail: [email protected] D. N. Mintz Associate Attending Radiologist, Hospital for Special Surgery, New York, NY, USA
Introduction Hemorrhagic neuropathy is a rare occurrence, defined as bleeding around or into a peripheral nerve resulting in impairment of nerve function [1]. This is often associated with corresponding neuropathic pain [2–5]. Although a patient’s symptomatology may mimic other more common causes of pain, pain distribution that follows the anatomic innervation pattern of a nerve and/or associated weakness of innervated musculature should raise suspicion for such an injury [1–9]. There are a multitude of factors that may contribute to hemorrhagic neuropathy, including trauma, neoplasm, anticoagulation, and bleeding disorders [1]. The resulting neuropathy is most commonly attributed to extraneural hemorrhage resulting in nerve compression. Intraneural hematomas, although quite rare, have also been described in the literature. Cases previously described include intraneural hematomas of the sciatic [1], femoral [5], median [3, 4, 7], ulnar [7], optic [8], and oculomotor [9] nerves. Typically patients experienced some trauma or had an underlying bleeding diathesis secondary to medications, or heritable or acquired disorders. Here we report the case of a healthy young patient with a spontaneous, unprovoked, symptomatic intraneural hematoma of her sural nerve. This was identified via MRI and was treated successfully with neurolysis and evacuation of the hematoma. Postoperatively the patient had complete resolution of her neuropathic symptoms.
E. F. DiCarlo Associate Attending Pathologist, Hospital for Special Surgery, New York, NY, USA
Case report
A. J. Weiland Attending Orthopaedic Surgeon, Hospital for Special Surgery, New York, NY, USA
The institutional review board approved this case report and provided waiver of documentation of informed consent and HIPAA authorization.
Skeletal Radiol
A 36-year-old previously healthy Caucasian female presented with a complaint of spontaneous posterior right knee pain for 2 months. She was unable to link its onset to any clear event. The pain was episodic and electric, radiating down the lateral aspect of her leg and occasionally to her small toe. She had no weakness or mechanical symptoms related to her knee. Her only medication was celecoxib, which she was taking for pain but only after the onset of these symptoms. Her past surgical history included only tonsillectomy. On physical examination, the patient’s gait was normal. There were no skin lesions. She had point tenderness over the distal aspect of the popliteal fossa, in the posterior midline, and a positive Tinel’s sign over this area. No mass was palpable. Knee range of motion was 0–130° of flexion. The ligamentous examination was normal. She had normal power in her right lower extremity. Her sensation was intact in the distribution of all lower extremity sensory nerves, including the sural nerve. Her laboratory test results were within normal limits, including coagulation studies. Magnetic resonance imaging (MRI) with and without contrast was obtained (Figs. 1 and 2). The MRI was performed on a 3-T magnet (General Electric Brilliance 750, Milwaukee, WI) using a dedicated transmit/receive eight-channel knee coil (Invivo, Gainesville, FL) using sagittal, axial, and coronal intermediate TE fast spin echo (FSE) sequences, a sagittal inversion recovery sequence, and axial FSE T1-weighted, fat-suppressed sequences before and after intravenous gadolinium (Omniscan). A mass was noted longitudinally along the sural nerve, measuring 1.6 cm. It was heterogeneous with surrounding edema. The center had high signal on the pre-contrast T1-weighted sequence that did not enhance, which was consistent with either mucinous material or hemorrhage. The radiographic differential diagnosis included nerve sheath tumor with associated hematoma or degeneration, varix, and hematoma. A degenerated nerve sheath tumor was unlikely as this would not be expected to be associated with edema. Varix was less likely given that the mass was
associated with the nerve itself, rather than a vein. The remaining considerations were hemorrhagic nerve sheath tumor and hematoma. The pre-contrast T1-weighted sequence was important in making a specific diagnosis, since it suggested the presence of hemorrhage, and hematoma was favored because an underlying nerve sheath tumor was not present. The patient underwent exploration and excision of this lesion. The patient was positioned prone, spinal anesthesia was used, and a non-sterile tourniquet was employed. A transverse incision was made over the patient’s point of maximal tenderness, and the sural nerve was identified (Fig. 3). A bluish lesion in the sural nerve was discovered, measuring about 1 cm×0.5 cm. The nerve sheath was opened and intrafascicular dissection was performed, removing the hemorrhagic lesion. Histopathologic analysis was consistent with hematoma (Fig. 4). The patient was seen for follow-up visits 2 and 6 weeks after surgery. She had an uncomplicated postoperative course with complete resolution of her neuropathic pain and was cleared to resume full normal activity. Routine follow-up was planned to continue, including 3-month and 1year office visits.
Fig. 1 Axial MRI. The arrow points to the mass associated with the sural nerve. The mass shows high signal on the proton density (a) and precontrast T1-weighted (b) sequences. There is peripheral enhancement on the post-contrast fat-suppressed T1-weighted image (c), with predominant lack of enhancement of the lesion itself. The central high signal may be related to enhancement or may reflect the pre-contrast high T1 signal
Fig. 3 Intraoperative photographs. The skin and subcutaneous tissues of the popliteal fossa have been incised transversely over the point of maximal tenderness for the patient, and the proximal segment of the sural nerve (medial sural cutaneous nerve) is seen in continuity, with a 1 cm× 0.5 cm intraneural mass oriented longitudinally (a). The epineurium was incised, and the hemorrhage was evacuated (b), leaving the nerve fascicles intact (c)
Fig. 2 Sagittal MRI. Proton density (a) and inversion recovery (b) sequences of the knee showing the mass (white arrows) within the sural nerve (short white arrows). Note the surrounding high signal (edema) (black arrows) on the fat-suppressed sequence
Skeletal Radiol
Fig. 4 Lesion pathology. a Photomicrograph showing organizing hematoma with fibrosis and microvascular proliferation within a mucoid, collagenous stroma. The stroma is most organized on the left of the tissue section, with progressively less organization toward the right, which becomes predominantly residual blood. The left edge presents the periphery of the hematoma and the location of the neural capsule (H&E, ×10). b Higher magnification photomicrograph from a region present in a showing spindled fibroblastic and vascular endothelial cells within the mucoid, loosely collagenous stroma, which delicately infiltrates the residual blood of the hematoma (H&E, ×20)
Discussion The above case highlights the importance of having a high index of suspicion for nerve injury or compression in patients whose complaints follow a typical peripheral nerve distribution. Although intraneural hematoma is a rare occurrence, it is critical to identify these cases and decompress the nerve, to both relieve the patient’s current symptoms and allow for full neural recovery [10]. Intraneural hematoma cases previously described in the literature either followed a traumatic event or may have been associated with an underlying coagulopathy [1, 5, 7, 9]. However, this is not always true, as with the current case. It is possible that the described patient experienced some form of minor trauma to her nerve of which she was unaware, but to the best of her knowledge none occurred. Atraumatic intraneural hematomas have been previously reported in the optic nerve and the median nerve [3, 4, 8]. If one occurs in a peripheral sensory nerve, like it did in our patient, the symptoms can be subtle. Thus, it is important that in cases of acute peripheral nerve dysfunction without obvious precipitating events, this diagnosis should not be overlooked. If a peripheral nerve lesion is suspected, ultrasound may be a valuable initial imaging modality in guiding further workup. A recent study found that ultrasound studies done to evaluate peripheral nerve disease either confirmed the diagnosis or modified the patient’s diagnostic or treatment path in over 82 % of cases [11]. This patient did not have an ultrasound evaluation, and it may have been a useful initial imaging choice. However, MRI was diagnostic based on the observed characteristics of the hemorrhage. Microvascular proliferation around the periphery of the organizing hematoma, adjacent to the neural capsule, provided the characteristic peripheral enhancement seen on the post-contrast MRI sequences. The increased signal intensity of the hematoma on T1-weighted sequences may be explained by the degradation of oxyhemoglobin to methemoglobin [12].
The sural nerve arises in the popliteal fossa from the tibial nerve as the medial sural cutaneous nerve. In continues distally deep to the gastrocnemius muscle and the deep fascia. After becoming superficial at the junction of the middle and distal thirds of the leg, it receives variable contributions from a peroneal communicating nerve, forming the sural nerve proper, which courses laterally and distally to the lateral border of the foot and the fifth metatarsal [2, 6]. The superficial course of the sural nerve in the leg may predispose the nerve to injury from direct trauma [6]. Sural nerve entrapment from various sources is commonly reported [2], and intraneural sural ganglia and tumors have been reported [2]. Prior case reports have described extraneural compression due to intramuscular hematoma formation after direct trauma [6] or from sports-related injury resulting in local bleeding [2], while intraneural hematoma causing sural neuropathy has not been reported to our knowledge. In the former case conservative management for 2 weeks allowed for full nerve recovery [6]; in the latter surgical release of the nerve permitted full return of nerve function [2]. Animal studies have shown that the formation of intraneural hematoma and associated compression of nerve fibers result in axonal degeneration [13, 14], and a rat model examining recovery after iatrogenic sciatic intraneural hematoma showed that subjects who underwent surgical decompression had faster functional recovery as well as decreased nerve axon damage than those who did not [10]. When these cases are identified clinically, appropriate treatment has resulted in recovery of nerve function in the majority of cases [1–3, 8], but delayed presentation or diagnosis may impair full recovery [4, 5, 14]. Rodriguez et al. [5] reported on a patient who developed progressive quadriceps paresis and saphenous anesthesia 4 days after a femoral nerve block. A 10-cm femoral intraneural hematoma was discovered on imaging, and emergent decompression and epineurolysis were performed. After 4 months, motor recovery was documented but the patient had residual cutaneous anesthesia [5]. Similarly, Kokkinakis, et al. [4] reported suboptimal outcomes after delayed presentation of a patient with a spontaneous median nerve intraneural hematoma despite immediate evacuation upon diagnosis. Posterior knee and lateral leg pain is a symptom with a broad range of underlying causative pathologies. Given the numerous anatomic structures in the area, including vascular, neural, ligamentous, cartilaginous, and muscular structures, determining the underlying cause of a patient’s complaints can be daunting. The diagnosis can usually be made through a combination of clinical and imaging findings, but electrodiagnostic tests may be confirmatory [2]. Knowledge of the underlying anatomy and typical locations of common pathologies can help when narrowing the
Skeletal Radiol
list of likely causes of a patient’s complaint. It is critical to keep both the common and uncommon possibilities in mind, especially when a patient presents with a unique set of signs and symptoms that may correlate with a rare condition. This allows for expeditious diagnosis and treatment, enhanced recovery, and potentially spares the patient from significant and debilitating sequellae if left undiagnosed. Acknowledgments The authors would like to acknowledge the contributions of Eugene T.H. Ek, MBBS, PhD, for his efforts and contributions to the manuscript. Conflict of interest Each author certifies that he or she has no commercial associations (e.g., consultancies, stock ownership, equity interest, patent/licensing arrangements, etc.) that might pose a conflict of interest in connection with the submitted article. This report has received approval from the Institutional Review Board at the Hospital for Special Surgery. Work was performed at the Hospital for Special Surgery.
References 1. Richardson RR, Hahn YS, Siqueira EB. Intraneural hematoma of the sciatic nerve. Case report. J Neurosurg. 1978;49:298–300. 2. Bryan 3rd BM, Lutz GE, O’Brien SJ. Sural nerve entrapment after injury to the gastrocnemius: a case report. Arch Phys Med Rehabil. 1999;80:604–6.
3. Hayden JW. Median neuropathy in the carpal tunnel caused by spontaneous intraneural hemorrhage. J Bone Joint Surg Am. 1964;46: 1242–4. 4. Kokkinakis M, Hinsche A, Rajeev A. Spontaneous intraneural haematoma causing acute neuropathy of the median nerve. J Hand Surg Eur Vol. 2009;34:280–1. 5. Rodriguez J, Taboada M, Garcia F, et al. Intraneural hematoma after nerve stimulation-guided femoral block in a patient with factor XI deficiency: case report. J Clin Anesth. 2011;23:234–7. 6. Babwah T. Sural nerve injury in a footballer related to blunt leg trauma. Res Sports Med. 2012;20:70–3. 7. Greenberg MK, Sonoda T. Mononeuropathy multiplex complicating idiopathic thrombocytopenic purpura. Neurology. 1991;41:1517–8. 8. Gregory RP, Koutsoubelis G, Kerr RF, et al. Spontaneous intraneural haematoma of the optic nerve. J Neurol Neurosurg Psychiatry. 1991;54:653–4. 9. Miyao S, Takano A, Teramoto J, et al. Oculomotor nerve palsy due to intraneural hemorrhage in idiopathic thrombocytopenic purpura: a case report. Eur Neurol. 1993;33:20–2. 10. Scopel GP, Marques Faria JC, Orpheu SC, et al. Intraneural hematoma with extrinsic compression: experimental study in rats and therapeutic options. J Reconstr Microsurg. 2007;23:275–81. 11. Padua L, Liotta G, Di Pasquale A, et al. Contribution of ultrasound in the assessment of nerve diseases. Eur J Neurol. 2012;19:47–54. 12. Lee YS, Kwon ST, Kim JO, et al. Serial MR imaging of intramuscular hematoma: experimental study in a rat model with the pathologic correlation. Korean J Radiol. 2011;12:66–77. 13. Rayan GM, Gannaway JK, Pitha J, et al. Peripheral nerve changes following epineurial injection of saline and blood in rat sciatic nerve. Clin Orthop Relat Res. 1985;193:299–307. 14. Rayan GM, Pitha JV, Wisdom P, et al. Histologic and electrophysiologic changes following subepineurial hematoma induction in rat sciatic nerve. Clin Orthop Relat Res. 1988;229:257–64.
CASE REPORT
Spontaneous intraneural hematoma of the sural nerve Shawn S. Richardson & Alexander S. McLawhorn & Douglas N. Mintz & Edward F. DiCarlo & Andrew J. Weiland
Received: 22 July 2014 / Revised: 28 September 2014 / Accepted: 1 October 2014 # ISS 2014
Abstract Symptomatic intraneural hemorrhage occurs rarely. It presents with pain and/or weakness in the distribution following the anatomic innervation pattern of the involved nerve. When a purely sensory nerve is affected, the symptoms can be subtle. We present a previously healthy 36-year-old female who developed an atraumatic, spontaneous intraneural hematoma of her sural nerve. Sural dysfunction was elicited from the patient’s history and physical examination. The diagnosis was confirmed with magnetic resonance imaging, and surgical decompression provided successful resolution of her preoperative symptoms. To our knowledge, this entity has not been reported previously. Our case highlights the importance of having a high index of suspicion for nerve injury or compression in patients whose complaints follow a typical peripheral nerve distribution. Prior studies have shown that the formation of intraneural hematoma and associated compression of nerve fibers result in axonal degeneration, and surgical decompression decreases axonal degeneration and aids functional recovery. Keywords Hematoma . Magnetic resonance imaging . Microsurgery . Neuropathy . Sural nerve S. S. Richardson (*) : A. S. McLawhorn Orthopaedic Surgery Resident, Hospital for Special Surgery, 535 East 70th Street, New York, NY 10021, USA e-mail: [email protected] D. N. Mintz Associate Attending Radiologist, Hospital for Special Surgery, New York, NY, USA
Introduction Hemorrhagic neuropathy is a rare occurrence, defined as bleeding around or into a peripheral nerve resulting in impairment of nerve function [1]. This is often associated with corresponding neuropathic pain [2–5]. Although a patient’s symptomatology may mimic other more common causes of pain, pain distribution that follows the anatomic innervation pattern of a nerve and/or associated weakness of innervated musculature should raise suspicion for such an injury [1–9]. There are a multitude of factors that may contribute to hemorrhagic neuropathy, including trauma, neoplasm, anticoagulation, and bleeding disorders [1]. The resulting neuropathy is most commonly attributed to extraneural hemorrhage resulting in nerve compression. Intraneural hematomas, although quite rare, have also been described in the literature. Cases previously described include intraneural hematomas of the sciatic [1], femoral [5], median [3, 4, 7], ulnar [7], optic [8], and oculomotor [9] nerves. Typically patients experienced some trauma or had an underlying bleeding diathesis secondary to medications, or heritable or acquired disorders. Here we report the case of a healthy young patient with a spontaneous, unprovoked, symptomatic intraneural hematoma of her sural nerve. This was identified via MRI and was treated successfully with neurolysis and evacuation of the hematoma. Postoperatively the patient had complete resolution of her neuropathic symptoms.
E. F. DiCarlo Associate Attending Pathologist, Hospital for Special Surgery, New York, NY, USA
Case report
A. J. Weiland Attending Orthopaedic Surgeon, Hospital for Special Surgery, New York, NY, USA
The institutional review board approved this case report and provided waiver of documentation of informed consent and HIPAA authorization.
Skeletal Radiol
A 36-year-old previously healthy Caucasian female presented with a complaint of spontaneous posterior right knee pain for 2 months. She was unable to link its onset to any clear event. The pain was episodic and electric, radiating down the lateral aspect of her leg and occasionally to her small toe. She had no weakness or mechanical symptoms related to her knee. Her only medication was celecoxib, which she was taking for pain but only after the onset of these symptoms. Her past surgical history included only tonsillectomy. On physical examination, the patient’s gait was normal. There were no skin lesions. She had point tenderness over the distal aspect of the popliteal fossa, in the posterior midline, and a positive Tinel’s sign over this area. No mass was palpable. Knee range of motion was 0–130° of flexion. The ligamentous examination was normal. She had normal power in her right lower extremity. Her sensation was intact in the distribution of all lower extremity sensory nerves, including the sural nerve. Her laboratory test results were within normal limits, including coagulation studies. Magnetic resonance imaging (MRI) with and without contrast was obtained (Figs. 1 and 2). The MRI was performed on a 3-T magnet (General Electric Brilliance 750, Milwaukee, WI) using a dedicated transmit/receive eight-channel knee coil (Invivo, Gainesville, FL) using sagittal, axial, and coronal intermediate TE fast spin echo (FSE) sequences, a sagittal inversion recovery sequence, and axial FSE T1-weighted, fat-suppressed sequences before and after intravenous gadolinium (Omniscan). A mass was noted longitudinally along the sural nerve, measuring 1.6 cm. It was heterogeneous with surrounding edema. The center had high signal on the pre-contrast T1-weighted sequence that did not enhance, which was consistent with either mucinous material or hemorrhage. The radiographic differential diagnosis included nerve sheath tumor with associated hematoma or degeneration, varix, and hematoma. A degenerated nerve sheath tumor was unlikely as this would not be expected to be associated with edema. Varix was less likely given that the mass was
associated with the nerve itself, rather than a vein. The remaining considerations were hemorrhagic nerve sheath tumor and hematoma. The pre-contrast T1-weighted sequence was important in making a specific diagnosis, since it suggested the presence of hemorrhage, and hematoma was favored because an underlying nerve sheath tumor was not present. The patient underwent exploration and excision of this lesion. The patient was positioned prone, spinal anesthesia was used, and a non-sterile tourniquet was employed. A transverse incision was made over the patient’s point of maximal tenderness, and the sural nerve was identified (Fig. 3). A bluish lesion in the sural nerve was discovered, measuring about 1 cm×0.5 cm. The nerve sheath was opened and intrafascicular dissection was performed, removing the hemorrhagic lesion. Histopathologic analysis was consistent with hematoma (Fig. 4). The patient was seen for follow-up visits 2 and 6 weeks after surgery. She had an uncomplicated postoperative course with complete resolution of her neuropathic pain and was cleared to resume full normal activity. Routine follow-up was planned to continue, including 3-month and 1year office visits.
Fig. 1 Axial MRI. The arrow points to the mass associated with the sural nerve. The mass shows high signal on the proton density (a) and precontrast T1-weighted (b) sequences. There is peripheral enhancement on the post-contrast fat-suppressed T1-weighted image (c), with predominant lack of enhancement of the lesion itself. The central high signal may be related to enhancement or may reflect the pre-contrast high T1 signal
Fig. 3 Intraoperative photographs. The skin and subcutaneous tissues of the popliteal fossa have been incised transversely over the point of maximal tenderness for the patient, and the proximal segment of the sural nerve (medial sural cutaneous nerve) is seen in continuity, with a 1 cm× 0.5 cm intraneural mass oriented longitudinally (a). The epineurium was incised, and the hemorrhage was evacuated (b), leaving the nerve fascicles intact (c)
Fig. 2 Sagittal MRI. Proton density (a) and inversion recovery (b) sequences of the knee showing the mass (white arrows) within the sural nerve (short white arrows). Note the surrounding high signal (edema) (black arrows) on the fat-suppressed sequence
Skeletal Radiol
Fig. 4 Lesion pathology. a Photomicrograph showing organizing hematoma with fibrosis and microvascular proliferation within a mucoid, collagenous stroma. The stroma is most organized on the left of the tissue section, with progressively less organization toward the right, which becomes predominantly residual blood. The left edge presents the periphery of the hematoma and the location of the neural capsule (H&E, ×10). b Higher magnification photomicrograph from a region present in a showing spindled fibroblastic and vascular endothelial cells within the mucoid, loosely collagenous stroma, which delicately infiltrates the residual blood of the hematoma (H&E, ×20)
Discussion The above case highlights the importance of having a high index of suspicion for nerve injury or compression in patients whose complaints follow a typical peripheral nerve distribution. Although intraneural hematoma is a rare occurrence, it is critical to identify these cases and decompress the nerve, to both relieve the patient’s current symptoms and allow for full neural recovery [10]. Intraneural hematoma cases previously described in the literature either followed a traumatic event or may have been associated with an underlying coagulopathy [1, 5, 7, 9]. However, this is not always true, as with the current case. It is possible that the described patient experienced some form of minor trauma to her nerve of which she was unaware, but to the best of her knowledge none occurred. Atraumatic intraneural hematomas have been previously reported in the optic nerve and the median nerve [3, 4, 8]. If one occurs in a peripheral sensory nerve, like it did in our patient, the symptoms can be subtle. Thus, it is important that in cases of acute peripheral nerve dysfunction without obvious precipitating events, this diagnosis should not be overlooked. If a peripheral nerve lesion is suspected, ultrasound may be a valuable initial imaging modality in guiding further workup. A recent study found that ultrasound studies done to evaluate peripheral nerve disease either confirmed the diagnosis or modified the patient’s diagnostic or treatment path in over 82 % of cases [11]. This patient did not have an ultrasound evaluation, and it may have been a useful initial imaging choice. However, MRI was diagnostic based on the observed characteristics of the hemorrhage. Microvascular proliferation around the periphery of the organizing hematoma, adjacent to the neural capsule, provided the characteristic peripheral enhancement seen on the post-contrast MRI sequences. The increased signal intensity of the hematoma on T1-weighted sequences may be explained by the degradation of oxyhemoglobin to methemoglobin [12].
The sural nerve arises in the popliteal fossa from the tibial nerve as the medial sural cutaneous nerve. In continues distally deep to the gastrocnemius muscle and the deep fascia. After becoming superficial at the junction of the middle and distal thirds of the leg, it receives variable contributions from a peroneal communicating nerve, forming the sural nerve proper, which courses laterally and distally to the lateral border of the foot and the fifth metatarsal [2, 6]. The superficial course of the sural nerve in the leg may predispose the nerve to injury from direct trauma [6]. Sural nerve entrapment from various sources is commonly reported [2], and intraneural sural ganglia and tumors have been reported [2]. Prior case reports have described extraneural compression due to intramuscular hematoma formation after direct trauma [6] or from sports-related injury resulting in local bleeding [2], while intraneural hematoma causing sural neuropathy has not been reported to our knowledge. In the former case conservative management for 2 weeks allowed for full nerve recovery [6]; in the latter surgical release of the nerve permitted full return of nerve function [2]. Animal studies have shown that the formation of intraneural hematoma and associated compression of nerve fibers result in axonal degeneration [13, 14], and a rat model examining recovery after iatrogenic sciatic intraneural hematoma showed that subjects who underwent surgical decompression had faster functional recovery as well as decreased nerve axon damage than those who did not [10]. When these cases are identified clinically, appropriate treatment has resulted in recovery of nerve function in the majority of cases [1–3, 8], but delayed presentation or diagnosis may impair full recovery [4, 5, 14]. Rodriguez et al. [5] reported on a patient who developed progressive quadriceps paresis and saphenous anesthesia 4 days after a femoral nerve block. A 10-cm femoral intraneural hematoma was discovered on imaging, and emergent decompression and epineurolysis were performed. After 4 months, motor recovery was documented but the patient had residual cutaneous anesthesia [5]. Similarly, Kokkinakis, et al. [4] reported suboptimal outcomes after delayed presentation of a patient with a spontaneous median nerve intraneural hematoma despite immediate evacuation upon diagnosis. Posterior knee and lateral leg pain is a symptom with a broad range of underlying causative pathologies. Given the numerous anatomic structures in the area, including vascular, neural, ligamentous, cartilaginous, and muscular structures, determining the underlying cause of a patient’s complaints can be daunting. The diagnosis can usually be made through a combination of clinical and imaging findings, but electrodiagnostic tests may be confirmatory [2]. Knowledge of the underlying anatomy and typical locations of common pathologies can help when narrowing the
Skeletal Radiol
list of likely causes of a patient’s complaint. It is critical to keep both the common and uncommon possibilities in mind, especially when a patient presents with a unique set of signs and symptoms that may correlate with a rare condition. This allows for expeditious diagnosis and treatment, enhanced recovery, and potentially spares the patient from significant and debilitating sequellae if left undiagnosed. Acknowledgments The authors would like to acknowledge the contributions of Eugene T.H. Ek, MBBS, PhD, for his efforts and contributions to the manuscript. Conflict of interest Each author certifies that he or she has no commercial associations (e.g., consultancies, stock ownership, equity interest, patent/licensing arrangements, etc.) that might pose a conflict of interest in connection with the submitted article. This report has received approval from the Institutional Review Board at the Hospital for Special Surgery. Work was performed at the Hospital for Special Surgery.
References 1. Richardson RR, Hahn YS, Siqueira EB. Intraneural hematoma of the sciatic nerve. Case report. J Neurosurg. 1978;49:298–300. 2. Bryan 3rd BM, Lutz GE, O’Brien SJ. Sural nerve entrapment after injury to the gastrocnemius: a case report. Arch Phys Med Rehabil. 1999;80:604–6.
3. Hayden JW. Median neuropathy in the carpal tunnel caused by spontaneous intraneural hemorrhage. J Bone Joint Surg Am. 1964;46: 1242–4. 4. Kokkinakis M, Hinsche A, Rajeev A. Spontaneous intraneural haematoma causing acute neuropathy of the median nerve. J Hand Surg Eur Vol. 2009;34:280–1. 5. Rodriguez J, Taboada M, Garcia F, et al. Intraneural hematoma after nerve stimulation-guided femoral block in a patient with factor XI deficiency: case report. J Clin Anesth. 2011;23:234–7. 6. Babwah T. Sural nerve injury in a footballer related to blunt leg trauma. Res Sports Med. 2012;20:70–3. 7. Greenberg MK, Sonoda T. Mononeuropathy multiplex complicating idiopathic thrombocytopenic purpura. Neurology. 1991;41:1517–8. 8. Gregory RP, Koutsoubelis G, Kerr RF, et al. Spontaneous intraneural haematoma of the optic nerve. J Neurol Neurosurg Psychiatry. 1991;54:653–4. 9. Miyao S, Takano A, Teramoto J, et al. Oculomotor nerve palsy due to intraneural hemorrhage in idiopathic thrombocytopenic purpura: a case report. Eur Neurol. 1993;33:20–2. 10. Scopel GP, Marques Faria JC, Orpheu SC, et al. Intraneural hematoma with extrinsic compression: experimental study in rats and therapeutic options. J Reconstr Microsurg. 2007;23:275–81. 11. Padua L, Liotta G, Di Pasquale A, et al. Contribution of ultrasound in the assessment of nerve diseases. Eur J Neurol. 2012;19:47–54. 12. Lee YS, Kwon ST, Kim JO, et al. Serial MR imaging of intramuscular hematoma: experimental study in a rat model with the pathologic correlation. Korean J Radiol. 2011;12:66–77. 13. Rayan GM, Gannaway JK, Pitha J, et al. Peripheral nerve changes following epineurial injection of saline and blood in rat sciatic nerve. Clin Orthop Relat Res. 1985;193:299–307. 14. Rayan GM, Pitha JV, Wisdom P, et al. Histologic and electrophysiologic changes following subepineurial hematoma induction in rat sciatic nerve. Clin Orthop Relat Res. 1988;229:257–64.
