Far lateral lumbar disc herniation part 1: Imaging, neurophysiology and clinical features

Abstract

Far lateral lumbar disc herniations (FLLDH) represent a separate category of disc pathology which includes both intraforaminal and extraforaminal lumbar disc herniations, that are characterized by a peculiar clinical presentation, diagnostic and treatment modalities as compared to the more frequent median and paramedian disc hernias. Surgical treatment often represents the only effective weapon for the cure of this disease and over the years different approaches have been developed that can reach the region of the foramen or external to it, with different degrees of invasiveness. The diagnosis is more demanding and still underestimated as it requires a more detailed knowledge in the spine anatomy and dedicated radiological studies. Computerized tomography and in particular magnetic resonance imaging are the appropriate tools for the diagnosis of FLLDH. Despite the widespread use of these diagnostic tests, many cases of FLLDH are overlooked due to insufficiently detailed radiological examinations or due to the execution of exams not focused to the foraminal or the extraforaminal region. Neurophysiological studies represent a valid aid in the diagnostic classification of this pathology and in some cases they can facilitate the differential diagnosis with other types of radiculopathies. In the present study, a comprehensive review of the clinical presentation, epidemiology, radiological study and the neurophysiological aspects is presented.

A Modified Approach for Minimally Invasive Tubular Microdiscectomy for Far Lateral Disc Herniations: Docking at the Caudal Level Transverse Process

“…Additionally, in a cadaveric study, it was found that drilling of the caudal TP, or in the case of L5-S1 FLDH the superior sacral ala, most easily exposed the exiting nerve root while also providing access to the disc without need for further boney removal [ 24 ]. In almost all cases, the extraforaminal disc fragment will be caudal to the exiting nerve root and displace it superiorly and laterally [ 5 ]. Thus, the caudal TP will be the most consistent boney landmark for accessing the extraforaminal disc.…”

“…Physical examination demonstrated a profound weakness of her right foot, including 3/5 strength of the tibialis anterior, an inability to heel walk, and a numbness along an L4 dermatome. Given the presence of a severe motor deficit in the subacute period and a strong desire to regain her foot strength, a joint decision made with the patient led to pursuing early surgery rather than engaging in additional non-operative treatment with epidural steroid injection and physical therapy [ 5 ]. The patient’s body mass index (BMI) was 25.5 kg/m 2 .…”

“…There are various techniques for docking the tubular retractor, including on the facet joint, pars interarticularis, and the cranial transverse process (TP) [ 4 ]. The challenges for a minimally invasive surgery for FLDH consist in limited bony landmarks compared to soft-tissue elements, which results in a variation of where to dock the retractor [ 5 , 6 ]. The anatomy is also less familiar than midline posterior approaches, potentially creating spatial confusion.…”

“…The anatomy is also less familiar than midline posterior approaches, potentially creating spatial confusion. Further, the dorsal root ganglion (DRG) of the exiting nerve root is more susceptible to thermal and mechanical injury, requiring less manipulation than what is used during standard discectomy [ 1 , 5 ].…”

Comparable effectiveness of transforaminal endoscopic spine system technique combined with selective nerve root block between far lateral lumbar disc herniation and central or paracentral herniation

“…[ 5 , 6 ] Due to its atypical imaging and insidious onset, FLDH is often misdiagnosed. [ 7 , 8 ] It can be mainly divided into foraminal type, extra-foraminal type and mixed type. [ 9 ] The prolapsed disc often compresses the exiting root and ganglion, leading to severe radicular pain.…”