Stepan Capek

Recurrent rectal cancer causing lumbosacral plexopathy with perineural spread to the spinal nerves and the sciatic nerve: an anatomic explanation.

Several groups have reported cases of rectal cancer with carcinomatous involvement of the lumbosacral plexus and sciatic, obturator, pudendal, or spinal nerves. To our best knowledge, clear examples of perineural tumor spread in rectal carcinoma have not yet been described. We retrospectively reviewed clinical data and imaging studies of three patients with primary or recurrent rectal cancer involving the lumbosacral plexus. Imaging studies included MRI and 18FDG PET/CT scans in all (n = 3) patients, histological samples were available in two (n = 2). Imaging studies demonstrated distinct features of tumor spread from the organ to the plexus and beyond in all cases (n = 3), histological specimens demonstrated perineural involvement thus supporting our theory (n = 2). We present these three cases of perineural tumor spread in rectal cancer as a proof of concept. We hypothesize that not only our cases, but other similar reported cases can be explained anatomically by extension of the rectal cancer to the inferior hypogastric plexus with perineural tumor spread to the lumbosacral plexus using the pelvic and sacral splanchnic nerves as conduits. Once the tumor reaches the lumbosacral plexus, it can continue to spread proximally or distally. We believe that perineural spread of colon cancer represents an important, under‐recognized mechanism of recurrence to neighboring major nerves in the pelvis. Clin. Anat. 28:136–143, 2015.

Neural involvement in endometriosis: Review of anatomic distribution and mechanisms.

Endometriosis (EM) is an infrequent cause of peripheral neuropathy, most commonly sciatic. Perineural spread has recently been introduced as an alternate explanation for cases of lumbosacral or sciatic nerve EM. We performed a literature review to collect all reported cases of peripheral and central nervous system EM in search of anatomic patterns of involvement; potentially to support the perineural spread theory. If available, intraneural invasion and presence of peritoneal EM were recorded. The search revealed 83 articles describing 365 cases of somatic peripheral nervous EM and 13 cases of central nervous EM. The most frequently involved site was the sacral plexus (57%, n = 211), followed by the sciatic nerve (39%, n = 140). Other nerves were reported in significantly smaller numbers. Ninety seven percent (97%, n = 355) of peripheral nerve cases presented with pain, 20% (n = 72) reported weakness and 31% (n = 114), numbness. Thirty four percent (34%, n = 38) had solely intraneural EM of which 89% (n = 33) had no peritoneal EM (percentage based on available information). In the central nervous system, the conus medullaris and/or cauda equina constituted the majority of cases with 54% (n = 7). Apart from perineural spread, other discussed mechanisms include retrograde menstruation with peritoneal seeding, hematogenous and lymphogenous spread, stem cell implantation either hematogenously or via retrograde menstruation with subsequent EM differentiation, and coelomic or Müllerian duct metaplasia. We believe this literature review supports perineural spread as an alternate mechanism for EM of nerve, particularly the subgroup with intraneural EM and without peritoneal disease. Clin. Anat. 28:1029–1038, 2015.

Prostate cancer with perineural spread and dural extension causing bilateral lumbosacral plexopathy: case report

Perineural tumor spread in prostate cancer is emerging as a mechanism to explain select cases of neurological dysfunction and as a cause of morbidity and tumor recurrence. Perineural spread has been shown to extend from the prostate bed to the lumbosacral plexus and then distally to the sciatic nerve or proximally to the sacral and lumbar nerves and even intradurally. The authors present a case of a bilateral neoplastic lumbosacral plexopathy that can be explained anatomically as an extension of the same process: from one lumbosacral plexus to the contralateral one utilizing the dural sac as a bridge between the opposite sacral nerve roots. Their theory is supported by sequential progression of symptoms and findings on clinical examinations as well as high-resolution imaging (MRI and PET/CT scans). The neoplastic nature of the process was confirmed by a sciatic nerve fascicular biopsy. The authors believe that transmedian dural spread allows continuity of a neoplastic process from one side of the body to the other.

Targeted fascicular biopsy of the sciatic nerve and its major branches: rationale and operative technique.

OBJECT Nerve biopsy is typically performed in distal, noncritical sensory nerves without using imaging to target the more involved regions. The yield of these procedures rarely achieves more than 50%. In selected cases where preoperative evaluation points toward a more localized (usually a more proximal) process, targeted biopsy would likely capture the disease. Synthesis of data obtained from clinical examination, electrophysiological testing, and MRI allows biopsy of a portion of the major mixed nerves safely and efficiently. Herein, experiences with the sciatic nerve are reported and a description of the operative technique is provided. METHODS All cases of sciatic nerve biopsy performed between 2000 and 2014 were reviewed. Only cases of fascicular nerve biopsy approached from the buttock or the posterior aspect of the thigh were included. Demographic data, clinical presentation, and the presence of percussion tenderness for each patient were recorded. Reviewed studies included electrodiagnostic tests and imaging. Previous nerve and muscle biopsies were noted. All details of the procedure, final pathology, and its treatment implications were recorded. The complication rate was carefully assessed for temporary as well as permanent complications. RESULTS One hundred twelve cases (63 men and 49 women) of sciatic nerve biopsy were performed. Mean patient age was 46.4 years. Seventy-seven (68.8%) patients presented with single lower-extremity symptoms, 16 (14.3%) with bilateral lower-extremity symptoms, and 19 (17%) with generalized symptoms. No patient had normal findings on physical examination. All patients underwent electrodiagnostic studies, the findings of which were abnormal in 110 (98.2%) patients. MRI was available for all patients and was read as pathological in 111 (99.1%). The overall diagnostic yield of biopsy was 84.8% (n = 95). The pathological diagnoses included inflammatory demyelination, perineurioma, nonspecific inflammatory changes, neurolymphomatosis, amyloidosis, prostate cancer, injury neuroma, neuromuscular choristoma, sarcoidosis, vasculitis, hemangiomatosis, arteriovenous malformation, fibrolipomatous hamartoma (lipomatosis of nerve), and cervical adenocarcinoma. The series included 11 (9.9%) temporary and 5 (4.5%) permanent complications: 3 patients (2.7%) reported permanent numbness in the peroneal division distribution, and 2 patients (1.8%) were diagnosed with neuromuscular choristoma that developed desmoid tumor at the biopsy site 3 and 8 years later. CONCLUSIONS Targeted fascicular biopsy of the sciatic nerve is a safe and efficient diagnostic procedure, and in highly selected cases can be offered as the initial procedure over distal cutaneous nerve biopsy. Diagnoses were very diverse and included entities considered very rare. Even for the more prevalent diagnoses, the biopsy technique allowed a more targeted approach with a higher diagnostic yield and justification for more aggressive treatment. In this series, new radiological patterns of some entities were identified, which could be biopsied less frequently.

Perineural tumor spread of bladder cancer causing lumbosacral plexopathy: an anatomic explanation

We present two cases of biopsy-proven neoplastic lumbosacral plexopathy from perineural spread of bladder cancer: one patient presented with predominantly sciatic nerve involvement and the second predominantly with obturator nerve involvement. These two patterns of perineural spread from bladder cancer were supported by imaging in our cases and solidified by review of the literature. Based on the innervation of the bladder, we provide an anatomic explanation for this observation. To our best knowledge, such an anatomic, mechanistic basis for perineural tumor spread in bladder cancer has not yet been described.

Magnetic resonance imaging evidence for perineural spread of endometriosis to the lumbosacral plexus: report of 2 cases

Sciatic nerve endometriosis (EM) is a rare presentation of retroperitoneal EM. The authors present 2 cases of catamenial sciatica diagnosed as sciatic nerve EM. They propose that both cases can be explained by perineural spread of EM from the uterus to the sacral plexus along the pelvic autonomie nerves and then further distally to the sciatic nerve or proximally to the spinal nerves. This explanation is supported by MRI evidence in both cases. As a proof of concept, the authors retrieved and analyzed the original MRI studies of a case reported in the literature and found a similar pattern of spread. They believe that the imaging evidence of their institutional cases together with the outside case is a very compelling indication for perineural spread as a mechanism of EM of the nerve.

Tumefactive appearance of peripheral nerve involvement in hematologic malignancies: a new imaging association

ObjectiveIn neurolymphomatosis (NL), the affected nerves are typically described to be enlarged and hyperintense on T2W MR sequences and to avidly enhance on gadolinium-enhanced T1WI. This pattern is highly non-specific. We recently became aware of a “tumefactive pattern” of NL, neuroleukemiosis (NLK) and neuroplasmacytoma (NPLC), which we believe is exclusive to hematologic diseases affecting peripheral nerves.Materials and methodsWe defined a “tumefactive” appearance as complex, fusiform, hyperintense on T2WI, circumferential tumor masses encasing the involved peripheral nerves. The nerves appear to be infiltrated by the tumor. Both structures show varying levels of homogenous enhancement. We reviewed our series of 52 cases of NL in search of this pattern; two extra outside cases of NL, three cases of NLK, and one case of NPLC were added to the series.ResultsWe identified 20 tumefactive lesions in 18 patients (14 NL, three NLK, one NPLC). The brachial plexus (n = 7) was most commonly affected, followed by the sciatic nerve (n = 6) and lumbosacral plexus (n = 3). Four patients had involvement of other nerves. All were proven by biopsy: the diagnosis was high-grade lymphoma (n = 12), low-grade lymphoma (n = 3), acute leukemia (n = 2), and plasmacytoma (n = 1).ConclusionsWe present a new imaging pattern of “tumefactive” neurolymphomatosis, neuroleukemiosis, or neuroplasmacytoma in a series of 18 cases. We believe this pattern is associated with hematologic diseases directly involving the peripheral nerves. Knowledge of this association can provide a clue to clinicians in establishing the correct diagnosis. Bearing in mind that tumefactive NL, NLK, and NPLC is a newly introduced imaging pattern, we still recommend to biopsy patients with suspicion of a malignancy.

Do cutaneous nerves cross the midline

Standard cutaneous innervation maps show strict midline demarcation. Although authors of these maps accept variability of peripheral nerve distribution or occasionally even the midline overlap of cutaneous nerves, this concept seems to be neglected by many other anatomists. To support the statement that such transmedian overlap exists, we performed an extensive literature search and found ample evidence for all regions (head/neck, thorax/abdomen, back, perineum, and genitalia) that peripheral nerves cross the midline or communicate across the midline. This concept has substantial clinical implications, most notably in anesthesia and perineural tumor spread. This article serves as a springboard for future anatomical, clinical, and experimental research. Clin. Anat. 28:96–100, 2015.

Perineural spread of squamous cell carcinoma: From skin to skin through the brachial plexus

Department of Neurosurgery, Mayo Clinic, 200 First St. SW, Rochester, MN, USA International Clinical Research Center, St. Anne’s University Hospital Brno, Pekarska 53, Brno, 656 91, Czech Republic Department of Radiology, Mayo Clinic, 200 First St. SW, Rochester, MN, USA Department of Pathology, Mayo Clinic, 200 First St. SW, Rochester, MN, USA Department of Neurology, Mayo Clinic, 200 First St. SW, Rochester, MN, USA

Perineural tumor spread to the muscle: An alternative for muscle metastasis?

Our group recently published in Clinical Anatomy an article describing the perineural spread of rectal cancer (Capek et al., 2014), but similar spread has been demonstrated in bladder (Aghion et al., 2014), prostate (Ladha et al., 2006; Hebert-Blouin et al., 2010), and cervical (Howe et al., 2013) cancers. We extended our understanding of this mechanism when we proposed that perineural spread provides an alternate explanation for regional osseous metastases. We wonder whether the same hypothesis could explain regional metastases in the skeletal muscle. An 83-year-old man was diagnosed with neoplastic lumbosacral plexopathy four years after an initial diagnosis of bladder cancer. Imaging studies revealed distinct characteristics of a perineural tumor having spread to the L4-S1 spinal nerves and the sciatic and obturator nerves (Figs. 1a and 1b). The neoplastic nature of the lumbosacral plexopathy was confirmed by biopsy. Specifics of the anatomical pathway are described in a separate article (Aghion et al., 2014). MRI further demonstrated a circumferentially enhancing mass in the obturator internus muscle (Fig. 1b). An F-deoxy-glucose positron emission tomography/ computed tomography scan demonstrated increased uptake in the same lesion in the left obturator internus muscle, three lung nodules, three mediastinal lymph nodes, and the left ischium (Fig. 1c). For this letter, careful reinterpretation of the pelvic MRI demonstrated an area of signal abnormality extending from the L5–S1 portion of the lumbosacral plexus to the obturator internus muscle, presumably along the nerve to the obturator internus (Fig. 1d). This correlates with the segmental innervation of the obturator internus muscle (Aung et al., 2001; Standring, 2008). We believe that tumors can spread from the lumbosacral plexus along the motor branches and then across the neuromuscular junction to the muscle (Fig. 2). Similar perineural spread of cancer to the muscle has been demonstrated in head and neck cancer. Zhu et al. (2004) reported spread of squamous cell carcinoma along the third nerve to the orbital rectal muscle. A similar case was presented by Wilcsek et al. (2000). Furthermore, perineural spreading in the opposite direction was observed in a case of rhabdomyosarcoma, which spread from the masticatory muscles along the trigeminal nerve (Freling et al., 2010; Bathla and Hegde, 2013). We wonder whether our proposed mechanism could explain other cases of regional muscle metastases in patients with pelvic malignancy accompanied by neurological symptoms. Nagao et al. (2004) reported metastases of a bladder cancer to the sciatic nerve and the ipsilateral gluteus maximus and the obturator externus muscles. Agar et al. (2004) described a case of cervical cancer presenting with lumbosacral plexopathy and metastases in the ipsilateral psoas muscle. Warde and Gospodarowicz (1993) reported a case of prostate cancer metastasis to the iliac muscle accompanied by leg weakness. Caskey and Fishman (1988) described a case of colon cancer metastasizing to the psoas muscle with intraspinal extension causing a block at the L4 level and cauda equina syndrome. A review of the literature revealed several other cases that could be explained by our hypothesis (Cohen et al., 1986; Herring et al., 1998; Nabi et al., 2003; Plaza et al., 2008; Tunio et al., 2010), but in neither of these was the patient’s neurological status reported in sufficient detail. Although we acknowledge other possible explanations, such as hematogenous spread or direct invasion from the adjacent infiltrated obturator nerve, we believe that the evidence presented in support of our hypothesis is very compelling.