Cervicothoracic ventral-dorsal rhizotomy for bilateral upper-extremity hypertonia in cerebral palsy: illustrative case

Abstract

BACKGROUND

Management of medically refractory limb-specific hypertonia is challenging. Neurosurgical options include deep brain stimulation, intrathecal baclofen, thalamotomy, pallidotomy, or rhizotomy. Cervical dorsal rhizotomy has been successful in the treatment of upper-extremity spasticity. Cervical ventral and cervical ventral-dorsal rhizotomy (VDR) has been used in the treatment or torticollis and traumatic hypertonia; however, the use of cervicothoracic VDR for the treatment of upper-extremity mixed hypertonia is not well described.

OBSERVATIONS

A 9-year-old girl with severe quadriplegic mixed hypertonia secondary to cerebral palsy (CP) underwent cervicothoracic VDR. Modified Ashworth Scale scores, provision of caregiving, and examination improved. Treatment was well tolerated.

LESSONS

Cervicothoracic VDR can afford symptomatic and quality of life improvement in patients with medically refractory limb hypertonia. Intraoperative positioning and nuances in surgical techniques are particularly important based on spinal cord position as modified by scoliosis. Here, the first successful use of cervicothoracic VDR for the treatment of medically refractory upper-limb hypertonia in a pediatric patient with CP is described.

Movement disorders are defined by involuntary movements phenomenologically defined as hyperkinetic, hypokinetic, and ataxic motor movements.^1,2 Hypertonia, a form of hyperkinetic movement disorder, is most commonly spastic, dystonic, or mixed and occurs secondary to etiologies including cerebral palsy (CP), hypoxic ischemic encephalopathy (HIE), central nervous system infection, stroke, or other heredodegenerative or traumatic conditions.^1,3 A recent meta-analysis estimated the incidence of CP to be 2.11 cases in 1000 live births.⁴ Treatment for focal or generalized hypertonia includes antispasmodic centrally acting medications, supportive therapies, and injections with botulinum toxin or phenol.^5–7 Hypertonia refractory to medical management is indicated for neurosurgical intervention. Severe forms of hypertonia present as rigidity and are often a mixture of dystonia, spasticity, and dyskinetic movements.

Focal, segmental, or limb-specific hypertonia differs from generalized dystonia in both etiology and treatment. For those affected by nongeneralized conditions, neurosurgical procedures such as pallidotomy, thalamotomy, deep brain stimulation (DBS), or intrathecal baclofen therapy (ITB) can have too broad an impact. Instead, peripheral treatment with bracing, treatment of the underlying condition, or peripheral rhizotomy can be more beneficial. Cervical dorsal rhizotomy has been used for upper extremity–specific spasticity and has led to improvement in tone with variable impact on function. Cervical ventral rhizotomy has shown success in the treatment of torticollis and limb denervation for traumatic hypertonia.^8–10 Albright and Tyler-Kabara¹¹ first described the use of combined cervical ventral and dorsal rhizotomies in three patients and cervicothoracic ventral-dorsal rhizotomy (VDR) in one patient, noting improvement in hypertonia. Additionally, lumbosacral VDR has been known to provide palliation in cases of bilateral lower-extremity spastic, dystonic hypertonia, with better than 50% improvement on the modified Ashworth Scale (mAS) and Barry-Albright Dystonia Scale.¹²

There is a paucity of literature on the evolving role of cervical VDR in the management of limb-specific movement disorders. We present a case of a pediatric patient with severe bilateral upper-extremity hypertonia who was treated with nonselective cervicothoracic VDR; she also underwent a lumbosacral VDR for bilateral lower-extremity mixed hypertonia. We include an annotated intraoperative video (Video 1) describing our technique to highlight surgical indications for and special considerations with this technique, as well as lessons learned.

VIDEO 1. Clip from three cases showing nuances in surgical techniques based on the spinal cord position as modified by scoliosis and tips to achieve effective tone reduction using cervicothoracic VDR. Click here to view.

Illustrative Case

Presentation

A 9-year-old female had a history of HIE, CP, and severe quadriplegic mixed spastic, dystonic hypertonia of the bilateral upper and lower extremities. This resulted in painful sustained clonus of the biceps and brachioradialis muscles of the bilateral upper extremities, with a manual muscle examination documenting a score of 4 on the mAS, on which 0 is no increase in muscle tone and 4 is a muscle group rigid in flexion or extension.¹³ Previous treatment for her mixed hypertonia included physical and occupational therapy, polypharmacy with high doses of antispasmodic agents, and multifocal upper-extremity botulinum injections.

The patient and family were extensively counseled regarding potential treatment options within the complex care clinic, a multidisciplinary clinic involving neurosurgery, physiatry, and neurology. Discussions included continued medical management, ITB, and cervicothoracic and lumbosacral VDR. Given the systemic side effects of escalating medical management and a correlated loss of efficacy, medical management was not favored; similarly, the frequency of botulinum toxin injections was increasing with limited efficacy. We extensively discussed permanent denervation surgery by rhizotomy versus neuromodulation with ITB therapy, but the family did not want to proceed with implantation of a pump. Considering the patient’s pronounced symptoms from nonaccidental trauma, coupled with the absence of developmental progress since infancy and a prolonged history of reaching the upper limit of baclofen dosing at 40 mg per day, as well as logistical apprehensions regarding the required follow-up for ITB maintenance, the family sought a more permanent solution. For her mixed dystonic, spastic quadriplegic CP, the family agreed to a combined cervicothoracic and lumbosacral VDR under anesthesia. Each surgery aimed to nonselectively section the nerve roots to afflicted myotomes, that is, dorsal sectioning to decrease the constitutively active myotatic reflex arc underlying spasticity and ventral sectioning to decrease the efferent activation of muscle units caused by dystonia.

Surgical Intervention

The patient was placed prone while under general anesthesia with very careful attention paid to positioning. We placed two intravenous catheters and performed bladder decompression; an arterial line is not routine. Neuromonitoring with needle electromyography was mediated by intramuscular placement of the needle electrodes listed in Table 1. Typical four-step surgical skin preparation, a surgical pause, and antibiosis were performed.

TABLE 1.

Electromyography needle placement

Muscle	Nerve Root
Deltoid	C5, C6
Biceps brachii	C5, C6
Brachioradialis	C5, C6
Triceps brachii	C6–8
Flexor carpi ulnaris	C7, C8
Abductor pollicis brevis	C8, T1
Abductor digiti minimi	C8, T1
Intercostal	T1–2

We began with a midline incision confirmed with fluoroscopy overlying C5–T1. A bilateral paraspinal dissection was performed to expose the lamina, and this was confirmed with fluoroscopy. We used a footplate drill to perform an osteoplastic laminoplasty, keeping the dorsal elements contiguous and reflected cephalad. Hemostasis was obtained with Gelfoam and long patties placed in the lateral recess to minimize venous plexus bleeding with dural opening. We exchanged loupe magnification for the intraoperative microscope. We performed a midline dural incision and reflected the dural edges laterally to maximize exposure of the nerve roots. The arachnoidal investment of the cervical spinal cord was opened using microneurosurgical instruments, including individual arachnoidal root sleeve dissection. The operator used the Gilette nerve hooks to gather the most cephalad mixed nerve root and threshold that root, noting that it activated the C6 myotome (Video 1). This was confirmed radiographically using fluoroscopy if necessary. The mixed root was then released, and the dorsal root was independently gathered, stimulated to threshold, and then 80%–90% of the dorsal root was sectioned by the assistant using microscissors. Similarly, the ventral root was gathered, stimulated to threshold, and 80%–90% was sectioned volumetrically. Minor bleeding was treated with Gelfoam; persistent radicular bleeding was coagulated with low-setting bipolar electrocautery.

We performed consecutive sequential sectioning in a caudal direction, sometimes aided by sectioning of the denticulate ligament to free the spinal cord or expose an operative trajectory. We proceeded ipsilaterally, sectioning C6, C7, C8, and T1 nerve roots. If included in the operative field, stimulation of T2 elicited an intercostal response and should remain intact. The same technique was applied to the contralateral side, with the operator and assistant switching roles, until sectioning was complete. We obtained hemostasis and closed the dura with a running 5-0 GORE-TEX stitch in a watertight fashion. Dural sealant and vancomycin powder were placed epidurally, and a laminoplasty was performed using the Medtronic Centerpiece laminoplasty plating system with reapproximation of the posterior tension band. The wound was then copiously irrigated with vancomycin and closed in standard multilayered fashion. The patient can remain for the lumbosacral VDR (as in our case) or transfer to the recovery room.

Postoperative Course and Outcomes

The patient recovered on our neurosurgical ward for approximately 2 weeks for respiratory support, pain control, physical and occupational therapies, and advancement of care unrelated primarily to the surgery itself. She experienced significant improvement of her mixed hypertonia, with physiatry measuring an mAS score of 0 in her bilateral upper and lower extremities. At her 2-week postoperative visit, she had an mAS score of 1–2 in the treated myotomes of her bilateral upper extremities, with improved positioning in her wheelchair and relaxation of her hand position. She had a dehiscent lumbosacral wound, which required surgical debridement and a 10-day course of clindamycin. At the 6-month follow-up, she was doing well, her hands sustained an open position without pain, and she had durable mAS scores of 1 in her treated myotomes (Table 2).

TABLE 2.

Upper-extremity mAS scores over time

Time Point	Proximal	Distal
Baseline	4	4
2 wks postop	1	2
6 mos postop	1	2

Patient Informed Consent

The necessary patient informed consent was obtained in this study.

Discussion

Observations

We present a case of a 9-year-old female with mixed spastic, dystonic quadriplegic hypertonia with sustained clonus and rigidity in the bilateral upper extremities. Her functional ability was classified as Gross Motor Function Classification System level 5 with painful spasms causing nonfunctional upper extremities. Bilateral cervicothoracic VDRs reduced both the afferent and efferent pathways, targeting her complex underlying pathophysiology and resulting in reduced tone and overall improvement in quality of life indicators. These cases pose unique challenges to the surgical team because of the associated spinal deformities, spasmodic contractures, and ventral location of the nerve roots.

Albright and Tyler-Kabara¹¹ illustrated the feasibility of cervicothoracic VDR in a single patient through a C5–T1 ventral and dorsal rhizotomy, sectioning 80% of the dorsal roots and 66% of the ventral roots. It has been theorized that higher sectioning of the ventral roots could lead to severe muscle atrophy. We employed nonselective sectioning of 80%–90% of both the ventral and dorsal roots without any signs of atrophy, demonstrating that this level of sectioning is safe and effective.

This case highlights the surgical indications, techniques, and considerations when treating hypertonia of the upper extremities. Cervicothoracic VDRs are indicated in patients with medically intractable upper-extremity hypertonia who do not use their extremities. Cervicothoracic VDR can also be preferred in patients with generalized pediatric movement disorders in addition to lumbosacral VDR. This surgery cannot be considered a gain-of-function surgery, although it does reliably decrease hypertonia. It can be a good option for total care patients affected by nociceptive pain from hypertonia-related muscle spasms, bone and joint deformity, tone-related caregiver concerns, or quality of life limitations. It is a safe alternative in patients who are poor candidates for DBS, pallidotomy, or ITB or in whom these modalities have failed.

Positioning

Operative positioning of patients with CP can often prove troublesome because of their significant spinal deformities, fixed limb contractures, and access tubes. Figure 1 illustrates intraoperative positioning, along with pre- and postoperative imaging. It shows that despite its complexity, achieving the correct positioning is feasible. Great care must be taken during positioning to prevent skin breakdown, inadvertent limb injury, or tube misadventure. The patient’s body habitus must be attended, as well as adequate head immobilization, while not interfering with effective intraoperative fluoroscopy.

FIG. 1.

Intraoperative positioning and imaging photographs showing surgical complexity. Anteroposterior (A) and lateral (B) positioning of a patient receiving combined cervicothoracic and lumbosacral VDR and baclofen catheter revision in the same surgery. Preoperative midsagittal cervical-thoracic computed tomography (CT) image (C) showing cervical-thoracic scoliosis and reversal of the natural lordosis, which leads to spinal cord rotation. Postoperative midsagittal cervical CT scan (D) of another patient obtained because of concerns for lumbar wound abscess, showing hyperlordosis and a lack of pathological signal intensity at 33 days. There was no radiographic effect on the spinal cord following cervical rhizotomy.

The position of the spine relative to the surgeon is a procedure-specific consideration. Scoliosis is the most common spinal deformity with an overall prevalence of 20% in this population.^14–16 It is defined as having an abnormal coronal curve on radiography with a Cobb angle of >10°, depending on the severity.¹⁷ Although very common, scoliosis does not change the orientation of the surgeon to the spinal cord.

Thoracic hyperkyphosis can lead to cervical hyperlordosis, which can occur when these sagittal curves exceed >50°.¹⁸ The incidence of these spinal deformities is not discretely known; however, estimates range from 4% to 7% with kyphosis and from 2% to 3% with lordosis.^19,20 Both cervical lordosis and kyphosis make the positioning of patients difficult while also greatly limiting the operating window of the surgeon.

Extreme lordosis shortens the distance from the occiput to the thorax, often causing skin creases, which are difficult to operate in and to heal. Lordosis repositions the spinal cord toward the surgeon, causing C6 and even C7 to be well hidden from view. Kyphosis presents the spinal cord falling away from the surgeon and is a more difficult paradigm. Optimal ergonomic positioning can be approximated by either adjusting the operative table using head up/down or Trendelenburg/reverse Trendelenburg. Surgery is aided by lateral rotation throughout the case to reposition the spinal cord and nerve roots in an appropriate fashion. Additionally, the patient can be bolstered with additional padding to high-pressure areas (e.g., iliac crest, clavicle) in an effort to overcome positioning irregularities and present the spinal cord orthogonally. Lordosis can usually be accommodated by neck flexion, Trendelenburg positioning, or performing additional levels of laminoplasty. In contradistinction, severe kyphosis, which cannot be corrected with either operative table manipulation or patient positioning changes, makes open cervical rhizotomy infeasible.

Spinal Cord Manipulation

To localize the ventral nerve roots for lesioning, the ventrolateral space must be accessed. Sectioning the ipsilateral dentate ligament with elevation and rotation of the spinal cord to the contralateral side can provide unobstructed access while limiting spinal cord injury. The safety of intraoperative spinal cord rotation has been well documented in cases of vascular malformation and tumor resection, emphasizing that gentle rotation of the spinal cord does not lead to significant adverse effects.^21–25 Although generally well tolerated during surgery, manipulation of the spinal cord, especially within the cervical region, has the potential to create devastating neurological consequences. Although no study has assessed the degree to which intraoperative rotation can lead to injury, intuitively, any spinal cord rotation should be limited as much as possible. One study evaluating the degree of preoperative spinal cord rotation and postoperative C5 palsy in patients with cervical degenerative disease found that a preoperative rotation of >6° led to increased rates of C5 palsy following anterior decompression.²⁶ Thus, restricting the degree of spinal cord rotation is imperative; however, gentle traction on the spinal cord is necessary to accurately section the ventral nerve roots.

The working corridor lateral to the spinal cord during microsurgical dissection is narrow, and this must be considered when planning the laminotomy to ensure sufficient lateral exposure. Sectioning of the denticulate ligament mobilizes the spinal cord, thus opening the lateral recess for dissecting and isolating nerve roots. This is particularly important to consider when performing ventral rhizotomies, because an understanding of this anatomy will help with intraoperative dissection and the myotomal activation confirmed with intraoperative neuromonitoring. Additionally, critical nerve roots must be preserved, specifically C3, C4, and C5, which contribute motor input to the phrenic nerve, driving the diaphragm’s innervation for respiration. We underscore the importance of neuromonitoring in the execution of rhizotomies, which confirms myotome level even if not used selectively in these cases.

Lessons

We present a case of a pediatric patient treated surgically with cervicothoracic VDR for mixed hypertonia. Indications, relevant operative approach, anatomy, and surgical considerations are discussed. Cervicothoracic VDR can afford symptomatic and quality of life improvement in patients with medically refractory limb hypertonia. Ensuring precise intraoperative positioning is crucial for achieving the appropriate surgical technique. Nuances in the approach can vary on the basis of spinal cord position, as modified by scoliosis.

Acknowledgments

We thank Jesse Arseneau for his assistance in preparing the accompanying video.

Author Contributions

Conception and design: Raskin, Trierweiler, LoPresti. Acquisition of data: Raskin, Kelly, Trierweiler. Analysis and interpretation of data: Raskin, Kelly, Kemeny, Abdelmageed, Trierweiler. Drafting the article: Raskin, Kelly, Kemeny, Abdelmageed, Trierweiler, LoPresti. Critically revising the article: all authors. Reviewed submitted version of manuscript: Raskin, Abdelmageed, Trierweiler, LoPresti. Approved the final version of the manuscript on behalf of all authors: Raskin. Administrative/technical/material support: Raskin, Trierweiler. Study supervision: Raskin.

Supplemental Information

Videos

• Video 1. https://vimeo.com/908722325.

Previous Presentations

Portions of this paper have been presented as oral presentations at the 46th annual meeting of the American Society of Pediatric Neurosurgeons, January 29–February 3, 2023, in San Juan, Puerto Rico; at the 77th annual meeting of the American Academy for Cerebral Palsy and Developmental Medicine, September 10–13, 2023, in Chicago, Illinois; and at the 49th annual meeting of the International Society for Pediatric Neurosurgery, October 15–19, 2023, in Viña Del Mar, Chile.