Practical considerations of linear accelerator‐based frameless extracranial radiosurgery for treatment of occipital neuralgia for nonsurgical candidates

Abstract

Occipital neuralgia generally responds to medical or invasive procedures. Repeated invasive procedures generate increasing complications and are often contraindicated. Stereotactic radiosurgery (SRS) has not been reported as a treatment option largely due to the extracranial nature of the target as opposed to the similar, more established trigeminal neuralgia. A dedicated phantom study was conducted to determine the optimum imaging studies, fusion matrices, and treatment planning parameters to target the C2 dorsal root ganglion which forms the occipital nerve. The conditions created from the phantom were applied to a patient with medically and surgically refractory occipital neuralgia. A dose of 80 Gy in one fraction was prescribed to the C2 occipital dorsal root ganglion. The phantom study resulted in a treatment achieved with an average translational magnitude of correction of 1.35 mm with an acceptable tolerance of 0.5 mm and an average rotational magnitude of correction of 0.4° with an acceptable tolerance of 1.0°. For the patient, the spinal cord was 12.0 mm at its closest distance to the isocenter and received a maximum dose of 3.36 Gy, a dose to 0.35 cc of 1.84 Gy, and a dose to 1.2 cc of 0.79 Gy. The brain maximum dose was 2.20 Gy. Treatment time was 59 min for 18, 323 MUs. Imaging was performed prior to each arc delivery resulting in 21 imaging sessions. The average deviation magnitude requiring a positional or rotational correction was 0.96 ± 0.25 mm, 0.8 ± 0.41°, whereas the average deviation magnitude deemed within tolerance was 0.41 ± 0.12 mm, 0.57 ± 0.28°. Dedicated quality assurance of the treatment planning and delivery is necessary for safe and accurate SRS to the cervical spine dorsal root ganglion. With additional prospective study, linear accelerator‐based frameless radiosurgery can provide an accurate, noninvasive alternative for treating occipital neuralgia where an invasive procedure is contraindicated.

Diffusion tensor imaging of the C1-C3 dorsal root ganglia and greater occipital nerve for cervicogenic headache

“…According to the criteria of the IHS proposed in 2004 [ 20 ], CGH diagnosis requires radiological evidence. We obtained GON tractography with reliability and performed a quantified analysis using DTI parameters from the C2-C3 DRG and GON, which were considered vulnerable to neuropathy in CGH [ 21 , 22 ]. We found that the DTI parameter of the FA value for the C2 DRG can be used for detecting severe headaches with high accuracy.…”

Treatment of occipital neuralgia using onabotulinum toxin A

“…During paroxysmal attacks, muscle contracture may occur, associated with residual pain (VAS: 5.4) 5,6,8‐10 , triggering points on the nerves 5 . Pain can be temporarily controlled by an anesthetic block of the affected nerve 7‐14 . Most cases are idiopathic, but secondary forms may result from trauma (C2 nerve root or ganglion compression), anatomical disorders (entrapment by hypertrophic atlanto‐epistropic ligament), degenerative causes (atlantoaxial subluxation in rheumatoid arthritis), infection (neurosyphilis), and tumors (multiple myeloma), as well as painful (polymyalgia rheumatica) and hormonal (acromegaly) syndromes 8,11‐13 .…”

“…block of the affected nerve [7][8][9][10][11][12][13][14] . Most cases are idiopathic, but secondary forms may result from trauma (C2 nerve root or ganglion compression), anatomical disorders (entrapment by hypertrophic atlanto-epistropic ligament), degenerative causes (atlantoaxial subluxation in rheumatoid arthritis), infection (neurosyphilis), and tumors (multiple myeloma), as well as painful (polymyalgia rheumatica) and hormonal (acromegaly) syndromes 8,[11][12][13] .…”

“…ON can be treated with anticonvulsants such as carbamazepine, oxcarbazepine, gabapentin, and pregabalin, or baclofen and amitriptyline [8][9][10]14 . Anesthetic block of the occipital nerve is not only a diagnostic criterion but also a therapeutic option, and its effects can last up to six months 7,[11][12][13] . Some cases may require repeated blocks over short periods of time, while others become refractory.…”