Letter to the Editor: Fibrolipoma
Mark A. Mahan, Caterina Giannini, and Robert J. Spinner
Letter to the Editor: Addendum: Evidence supports a “no-touch” approach to neuromuscular choristoma
Marie-Noëlle Hébert-Blouin, Kimberly K. Amrami, and Robert J. Spinner
Cerebrospinal fluid volume–depletion headaches in patients with traumatic brachial plexus injury
Marie-Noëlle Hébert-Blouin, Bahram Mokri, Alexander Y. Shin, Allen T. Bishop, and Robert J. Spinner
Patients with brachial plexus injury (BPI) present with a combination of motor weakness/paralysis, sensory deficits, and pain. Brachial plexus injury is generally not believed to be associated with headaches. However, CSF leaks may be associated with CSF volume–depletion (low-pressure) headaches and can occur in BPI secondary to nerve root avulsion. Only a few cases of headaches associated with BPI have been reported. It is unknown if headaches in patients with BPI occur so rarely, or if they are just unrecognized by physicians and/or patients in which the focus of attention is the affected limb. The aim of this study was to determine the prevalence of CSF volume–depletion headaches in patients with BPI.
All adult patients presenting at the Mayo brachial plexus clinic with traumatic BPI were asked to complete a questionnaire addressing the presence and quality of headaches following their injury. The patients' clinical, injury, and imaging characteristics were subsequently reviewed.
Between December 2008 and July 2010, 145 patients completed the questionnaire. Twenty-two patients reported new onset headaches occurring after their BPI. Eight of these patients experienced positional headaches, suggestive of CSF volume depletion. One of the patients with orthostatic headaches was excluded because the headaches immediately followed a lumbar puncture for a myelogram. Six of the other 7 patients with positional headaches had a clear preganglionic BPI. The available imaging studies in these 6 patients revealed evidence of CSF leaks: pseudomeningoceles (n = 5), CSF tracking into soft tissues (n = 3), CSF tracking into the intraspinal compartment (n = 3), CSF tracking into the pleural space (n = 2), and low-positioned cerebellar tonsils (n = 2).
In this retrospective study, 15.2% of patients (22 of 145 patients) with traumatic BPI suffered from a new-onset headache. Seven of these patients (4.8%) experienced postural headaches clearly suggestive of CSF volume depletion likely secondary to a CSF leak associated with the BPI, whereas the other 15 patients (10.3%) suffered headaches that may have represented a variant of CSF depletion headaches without a postural characteristic or a headache from another cause. These data suggest that CSF volume–depletion headaches occur in a significant proportion of patients with BPI and have been underrecognized and underreported.
Adipose lesions of nerve: the need for a modified classification
Robert J. Spinner, Bernd W. Scheithauer, Kimberly K. Amrami, Doris E. Wenger, and Marie-Noëlle Hébert-Blouin
Adipose lesions of nerve are rare and poorly understood. Their current classification, although not universally accepted, generally includes lipomatosis of nerve with or without localized macrodactyly, and intra- as well as extraneural lipoma. The authors believe that the spectrum of these lesions and their interrelationships are not currently appreciated. They propose an adaptation to the existing framework to illustrate the expanding spectrum of adipose lesions of nerve by considering lipomatosis and lipoma singly or in combination.
Fourteen representative cases are presented to demonstrate not only the intraneural and extraneural examples of lipomatosis and lipoma, but also their anatomical combinations.
Based on the cases presented and a careful literature review, a conceptual approach to the classification of adipose lesions of nerve is generated. This approach incorporates the 2 essential lesions, lipomatosis of nerve and lipoma, in both their intra- and extraneural forms. This permits expansion to encompass combinations.
To press the concept that adipose tumors of nerve are a broad but interrelated spectrum of lesions, the authors propose modification of the present classification system. This approach provides an orderly platform for progress, reflects understanding of these interrelated lesions, and facilitates optimal treatment by distinguishing resectable from nonresectable components.
Fibromatosis: a potential sequela of neuromuscular choristoma
Marie-Noëlle Hébert-Blouin, Bernd W. Scheithauer, Kimberly K. Amrami, Susan R. Durham, and Robert J. Spinner
Neuromuscular choristoma (NMC) is a rare peripheral nerve lesion in which mature skeletal muscle fibers lie within the nerve and its fascicles. Given limited follow-up, its natural history is poorly understood. The occurrence of aggressive fibromatosis in one of the authors' patients and its occurrence in reported cases suggests an etiological relationship between the 2 lesions. This study attempts to explain the association and its frequency.
All cases of NMCs seen in consultation or treated at the Mayo Clinic were identified. Demographic and clinical data were reviewed in cases with coexistent aggressive fibromatosis. Pathology and neuroimaging studies were reexamined. In addition, an extensive literature review was performed to explore the association of NMC with aggressive fibromatosis, with special attention given to pathological and imaging characteristics and the development of aggressive fibromatosis.
The authors identified 10 patients with a diagnosis of NMC who were treated at the Mayo Clinic between 1992 and 2010. Four of 5 with adequate follow-up had developed a definite or suspected aggressive fibromatosis. A review of the initial pathological specimens in these cases revealed no evidence of fibromatosis, but all of the lesions exhibited accompanying hypocellular collagenous tissue. On MR images, all cases showed areas of low signal intensity, which significantly differed from muscle, nerve, and NMC components. On available serial MR imaging studies, aggressive fibromatosis seemed to originate in such lower-intensity regions. In the 18 previously reported cases of NMC, 5 patients developed recurrent masses diagnosed as either definite (2 cases) or possible (3 cases) fibromatosis. Review of the published imaging studies in these cases suggests the presence of lower intensity areas similar to those observed in the 10 patients treated at the Mayo Clinic.
This study confirms that the development of aggressive fibromatosis in patients with NMC has been underreported. A direct relationship between the NMC and the development of aggressive fibromatosis is suggested by pathological and neuroimaging evidence.
Editorial: Cushing and peripheral nerves
David G. Kline
Reflections on the contributions of Harvey Cushing to the surgery of peripheral nerves
R. Shane Tubbs, Neal Patel, Brian Vala Nahed, Aaron A. Cohen-Gadol, and Robert J. Spinner
By the time Harvey Cushing entered medical school, nerve reconstruction techniques had been developed, but peripheral nerve surgery was still in its infancy. As an assistant surgical resident influenced by Dr. William Halsted, Cushing wrote a series of reports on the use of cocaine for nerve blocks. Following his residency training and a hiatus to further his clinical interests and intellectual curiosity, he traveled to Europe and met with a variety of surgeons, physiologists, and scientists, who likely laid the groundwork for Cushing's increased interest in peripheral nerve surgery. Returning to The Johns Hopkins Hospital in 1901, he began documenting these surgeries. Patient records preserved at Yale's Cushing Brain Tumor Registry describe Cushing's repair of ulnar and radial nerves, as well as his exploration of the brachial plexus for nerve repair or reconstruction. The authors reviewed Harvey Cushing's cases and provide 3 case illustrations not previously reported by Cushing involving neurolysis, nerve repair, and neurotization. Additionally, Cushing's experience with facial nerve neurotization is reviewed. The history, physical examination, and operative notes shed light on Cushing's diagnosis, strategy, technique, and hence, his surgery on peripheral nerve injury. These contributions complement others he made to surgery of the peripheral nervous system dealing with nerve pain, entrapment, and tumor.
Extreme intraneural ganglion cysts
Robert J. Spinner, Marie-Noëlle Hébert-Blouin, Michael G. Rock, and Kimberly K. Amrami
The mechanism responsible for exceptional examples of intraneural ganglia with extensive longitudinal involvement has not been understood. Such cases of intraneural cysts, seemingly remote from a joint, have been thought not to have articular connections. Decompression and attempted resection of the cyst has led to intraneural recurrence and poor neurological recovery. The purpose of this report is not only to clarify the pathogenesis of these cysts, but also to discuss their treatment based on modern concepts of intraneural ganglia.
Two examples of extreme longitudinal propagation of intraneural ganglia are presented.
A patient with a moderate tibial neuropathy was found to have a tibial intraneural ganglion. Prospective interpretation of the MR imaging study demonstrated the cyst's origin from the posterior portion of the superior tibiofibular joint (STFJ), with proximal extension within the sciatic nerve to the lower buttock region. Communication between the STFJ and the cyst was confirmed with direct knee MR arthrography. The tibial intraneural cyst was treated successfully by a relatively limited exposure in the distal popliteal fossa: the cyst was decompressed, the articular branch disconnected, and the STFJ resected. Postoperatively, the patient improved neurologically and there was no evidence of recurrent cyst on postoperative MR imaging. A second patient, previously reported by another group, was reexamined 22 years after surgery. This patient had an extensive peroneal intraneural ganglion that extended into the sciatic nerve from the knee to the buttock; no joint connection or recurrent cyst had initially been described. In this patient, the authors hypothesized and established with MR imaging the presence of both: a joint connection to the anterior portion of the STFJ from the peroneal articular branch as well as recurrent cyst within the peroneal and tibial nerves.
This paper demonstrates that extreme intraneural cysts are not clinical outliers but represent extreme examples of other more typical intraneural cysts. They logically obey the same principles, previously described in the unified articular (synovial) theory. The degree of longitudinal extension is probably due to high intraarticular pressures within the degenerative joint of origin. The generalizability of the mechanistic principles is highlighted by the fact that these 2 cases, involving the tibial and the peroneal nerve respectively, both extended well distant (that is, to the buttock) from the STFJ via their respective articular branch of origin. These extensive intraneural cysts can be treated successfully by disconnecting the affected articular branch and by resection of the joint of origin, rather than by a more aggressive operation resecting the cyst and cyst wall.